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Bibliography on: Sociobiology

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ESP: PubMed Auto Bibliography 18 Nov 2018 at 01:43 Created: 


Sociobiology is a field of scientific study that is based on the hypothesis that social behavior has resulted from evolution and attempts to examine and explain social behavior within that context. Sociobiology investigates social behaviors, such as mating patterns, territorial fights, pack hunting, and the hive society of social insects. It argues that just as selection pressure led to animals evolving useful ways of interacting with the natural environment, it led to the genetic evolution of advantageous social behavior. While the term "sociobiology" can be traced to the 1940s, the concept did not gain major recognition until the publication of Edward O. Wilson's book Sociobiology: The New Synthesis in 1975.

Created with PubMed® Query: sociobiology NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2018-11-12

Bastin F, Couto A, Larcher V, et al (2018)

Marked interspecific differences in the neuroanatomy of the male olfactory system of honey bees (genus Apis).

The Journal of comparative neurology [Epub ahead of print].

All honey bee species (genus Apis) display a striking mating behavior with the formation of male (drone) congregations, in which virgin queens mate with many drones. Bees' mating behavior relies on olfactory communication involving queen-but also drone pheromones. To explore the evolution of olfactory communication in Apis, we analyzed the neuroanatomical organization of the antennal lobe (primary olfactory center) in the drones of five species from the three main lineages (open-air nesting species: dwarf honey bees Apis florea and giant honey bees Apis dorsata; cavity-nesting species: Apis mellifera, Apis kochevnikovi, and Apis cerana) and from three populations of A. cerana (Borneo, Thailand, and Japan). In addition to differences in the overall number of morphological units, the glomeruli, our data reveal marked differences in the number and position of macroglomeruli, enlarged units putatively dedicated to sex pheromone processing. Dwarf and giant honey bee species possess two macroglomeruli while cavity-nesting bees present three or four macroglomeruli, suggesting an increase in the complexity of sex communication during evolution in the genus Apis. The three A. cerana populations showed differing absolute numbers of glomeruli but the same three macroglomeruli. Overall, we identified six different macroglomeruli in the genus Apis. One of these (called MGb), which is dedicated to the detection of the major queen compound 9-ODA in A. mellifera, was conserved in all species. We discuss the implications of these results for our understanding of sex communication in honey bees and propose a putative scenario of antennal lobe evolution in the Apis genus.

RevDate: 2018-11-07

Ruedenauer FA, Wöhrle C, Spaethe J, et al (2018)

Do honeybees (Apis mellifera) differentiate between different pollen types?.

PloS one, 13(11):e0205821 pii:PONE-D-18-01664.

Bees receive nectar and pollen as reward for pollinating plants. Pollen of different plant species varies widely in nutritional composition. In order to select pollen of appropriate nutritional quality, bees would benefit if they could distinguish different pollen types. Whether they rely on visual, olfactory and/or chemotactile cues to distinguish between different pollen types, has however been little studied. In this study, we examined whether and how Apis mellifera workers differentiate between almond and apple pollen. We used differential proboscis extension response conditioning with olfactory and chemotactile stimulation, in light and darkness, and in summer and winter bees. We found that honeybees were only able to differentiate between different pollen types, when they could use both chemotactile and olfactory cues. Visual cues further improved learning performance. Summer bees learned faster than winter bees. Our results thus highlight the importance of multisensory information for pollen discrimination.

RevDate: 2018-11-05

Egert-Berg K, Hurme ER, Greif S, et al (2018)

Resource Ephemerality Drives Social Foraging in Bats.

Current biology : CB pii:S0960-9822(18)31290-9 [Epub ahead of print].

Observations of animals feeding in aggregations are often interpreted as events of social foraging, but it can be difficult to determine whether the animals arrived at the foraging sites after collective search [1-4] or whether they found the sites by following a leader [5, 6] or even independently, aggregating as an artifact of food availability [7, 8]. Distinguishing between these explanations is important, because functionally, they might have very different consequences. In the first case, the animals could benefit from the presence of conspecifics, whereas in the second and third, they often suffer from increased competition [3, 9-13]. Using novel miniature sensors, we recorded GPS tracks and audio of five species of bats, monitoring their movement and interactions with conspecifics, which could be inferred from the audio recordings. We examined the hypothesis that food distribution plays a key role in determining social foraging patterns [14-16]. Specifically, this hypothesis predicts that searching for an ephemeral resource (whose distribution in time or space is hard to predict) is more likely to favor social foraging [10, 13-15] than searching for a predictable resource. The movement and social interactions differed between bats foraging on ephemeral versus predictable resources. Ephemeral species changed foraging sites and showed large temporal variation nightly. They aggregated with conspecifics as was supported by playback experiments and computer simulations. In contrast, predictable species were never observed near conspecifics and showed high spatial fidelity to the same foraging sites over multiple nights. Our results suggest that resource (un)predictability influences the costs and benefits of social foraging.

RevDate: 2018-11-04

Bang A (2018)

Antecedents of behavioural and reproductive dominance in pairs of the primitively eusocial wasp Ropalidia marginata.

Behavioural processes pii:S0376-6357(18)30243-2 [Epub ahead of print].

What factors predispose some individuals to become reproductively dominant in a group where every member can reproduce? Antecedents of reproductive dominance have often been investigated in primitively eusocial species where reproductive skew exists despite adult reproductive potential displayed by every group-member, but such studies have rarely focused on small, incipient colonies. Here, I investigated antecedents of behavioural and reproductive dominance in pairs of the Indian paper wasp Ropalidia marginata. Common antecedents of behavioural dominance such as body size and age were inoperative in pairs of R. marginata. Moreover, age and behavioural dominance, but not body size, influenced reproductive dominance in pairs. These findings are not only different from other primitively eusocial insects, but also different from the colonies of R. marginata. It is likely that antecedents of reproductive dominance are different not only in different species, but also change with group size within a species, such that the role of behavioural dominance to achieve reproductive monopoly remains more effective in small groups such as pairs, and becomes less effective as the group size increases. These results require further investigations into the effect of group size on individual behaviour in group-living animals.

RevDate: 2018-11-02

Faragalla KM, Chernyshova AM, Gallo AJ, et al (2018)

From gene list to gene network: Recognizing functional connections that regulate behavioral traits.

Journal of experimental zoology. Part B, Molecular and developmental evolution [Epub ahead of print].

The study of social breeding systems is often gene focused, and the field of insect sociobiology has been successful at assimilating tools and techniques from molecular biology. One common output from sociogenomic studies is a gene list. Gene lists are readily generated from microarray, RNA sequencing, or other molecular screens that typically aim to prioritize genes based on the differences in their expression. Gene lists, however, are often unsatisfying because the information they provide is simply tabular and does not explain how genes interact with each other, or how genetic interactions change in real time under social or environmental circumstances. Here, we promote a view that is relatively common to molecular systems biology, where gene lists are converted into gene networks that better describe the functional connections that regulate behavioral traits. We present a narrative related to honeybee worker sterility to show how network analysis can be used to reprioritize candidate genes based on connectivity rather than their freestanding expression values. Networks can also reveal multigene modules, motifs, clusters or other system-wide properties that might not be apparent from an ab initio list. We argue that because network analyses are not restricted to "genes" as nodes, their implementation can potentially connect multiple levels of biological organization into a single, progressively complex study system.

RevDate: 2018-10-23

Sommerlandt FMJ, Brockmann A, Rössler W, et al (2018)

Immediate early genes in social insects: a tool to identify brain regions involved in complex behaviors and molecular processes underlying neuroplasticity.

Cellular and molecular life sciences : CMLS pii:10.1007/s00018-018-2948-z [Epub ahead of print].

Social insects show complex behaviors and master cognitive tasks. The underlying neuronal mechanisms, however, are in most cases only poorly understood due to challenges in monitoring brain activity in freely moving animals. Immediate early genes (IEGs) that get rapidly and transiently expressed following neuronal stimulation provide a powerful tool for detecting behavior-related neuronal activity in vertebrates. In social insects, like honey bees, and in insects in general, this approach is not yet routinely established, even though these genes are highly conserved. First studies revealed a vast potential of using IEGs as neuronal activity markers to analyze the localization, function, and plasticity of neuronal circuits underlying complex social behaviors. We summarize the current knowledge on IEGs in social insects and provide ideas for future research directions.

RevDate: 2018-10-20

Sehner S, Fichtel C, PM Kappeler (2018)

Primate tails: Ancestral state reconstruction and determinants of interspecific variation in primate tail length.

American journal of physical anthropology [Epub ahead of print].

OBJECTIVE: Living primates vary considerably in tail length-body size relation, ranging from tailless species to those where the tail is more than twice as long as the body. Because the general pattern and determinants of tail evolution remain incompletely known, we reconstructed evolutionary changes in relative tail length across all primates and sought to explain interspecific variation in this trait.

METHODS: We combined data on tail length, head-body length, intermembral index (IMI), habitat use, locomotion type, and range latitude for 340 species from published sources. We reconstructed the evolution of relative tail length to identify all independent cases of regime shifts on a primate phylogeny, using several methods based on Ornstein-Uhlenbeck (OU) models. Accounting for phylogeny, we also examined the effects of habitat, locomotion type, distance from the equator and IMI on interspecific variation in tail length-body size relation.

RESULTS: Primate tail length is not sexually dimorphic. A phylogenetic reconstruction allowing multiple optima explains the observed regime shifts best. During the evolutionary history of primates, relative tail length changed 50 times under an OU model. Specifically, relative tail length increased 26 and decreased 24 times. Most of these changes occurred among Old World primates. Among the variables tested here, interspecific variation in IMI and the difference between leaping and non-leaping locomotion explained interspecific variation in relative tail length: Evolutionary decreases in relative tail length are generally associated with an increase in IMI and an absence of leaping behavior.

CONCLUSIONS: Regime shifts for relative tail length in living primates occurred in concert with fundamental changes in IMI and a change from leaping to non-leaping locomotion, or vice versa. Exceptions from this general pattern are linked to the presence of a prehensile tail or specialized foraging strategies. Thus, the primate tail appears to have evolved in functional coordination with limb proportions, presumably to assist body balance.

RevDate: 2018-10-08

Bernaldo de Quirós E, Wheeler BC, Hammerschmidt K, et al (2018)

Do sexual calls in female black capuchin monkeys (Sapajus nigritus) vary with fertility? An acoustic analysis.

American journal of primatology, 80(9):e22920.

Females across a range of animal taxa produce vocalizations and signals uniquely associated with periods of mating. While such signals may ultimately function to increase female attractivity to males, conflicting findings challenge the extent to which these signals co-vary in accordance with the probability of conception. Female black capuchin monkeys (Sapajus nigritus) display an elaborate repertoire of both vocal and visual components as part of their socio-sexual behavior, and previous analyses have shown that the rates of production of visual, but not vocal, components provide graded information on female ovulation. It remains possible, however, that the acoustic parameters of these sexual calls, rather than their rate of productions, co-vary with female fertility. To test this, we analyzed structural and temporal call parameters from estrous calls and post-copulatory calls recorded over five consecutive mating seasons in 12 sexually mature females at Iguazú National Park, Argentina. Calls given during the fertile phase of the female ovarian cycle were compared with those given during the non-fertile phase, as determined by profiles of female reproductive hormones. Similarly, within the fertile phase, we tested whether temporal or spectral acoustic parameters of calls gradually change with the approach of ovulation. We did not find any significant relationship between call parameters and the two measures of female fertility in either female estrous calls or post-copulatory calls. However, some differences between pre- and post-copulatory calls were apparent. Overall, our results indicate that sexual calls in black capuchin females do not provide precise information about the timing of ovulation, but may allow listeners to make probabilistic inferences about whether copulations have taken place. This, combined with previous findings, suggests that females in our study may use signals in different modalities to convey information about their fertility and sexual behavior with varying degrees of precision.

RevDate: 2018-09-18

Henke-von der Malsburg J, C Fichtel (2018)

Are generalists more innovative than specialists? A comparison of innovative abilities in two wild sympatric mouse lemur species.

Royal Society open science, 5(8):180480 pii:rsos180480.

The propensity to flexibly innovate behavioural variants might advantage animals when dealing with novel or modified ecological or social challenges. Interspecific innovative abilities can be predicted by the degree of ecological generalism and intraspecific variation is predicted by personality traits. To examine the effects of these factors on innovation, we compared problem-solving abilities in the generalist grey mouse lemurs (Microcebus murinus) and the more specialized Madame Berthe's mouse lemurs (Microcebus berthae) in western Madagascar. We examined personality traits by testing 54 individuals in open field and novel object tests, and we assessed problem-solving abilities by presenting an artificial feeding-box that could be opened by three different techniques. The first two techniques presented novel problems and the third technique a modified problem to the more complex second novel problem. In both species, motivation, early success and better inhibitory control characterized innovators and predicted superior problem-solving performance. Although both species performed equally well in finding a solution to the novel problems, the specialist species was more efficient in finding a novel solution to a familiar problem. Since the ecological specialist also exhibited more inhibitory control in this task than the generalist, we propose that specialists may dispose of more efficient problem-solving behaviour.

RevDate: 2018-09-17
CmpDate: 2018-09-17

Joiner TE, Buchman-Schmitt JM, Chu C, et al (2017)

A Sociobiological Extension of the Interpersonal Theory of Suicide.

Crisis, 38(2):69-72.

RevDate: 2018-08-30

Bernadou A, Schrader L, Pable J, et al (2018)

Stress and early experience underlie dominance status and division of labour in a clonal insect.

Proceedings. Biological sciences, 285(1885): pii:rspb.2018.1468.

Cooperation and division of labour are fundamental in the 'major transitions' in evolution. While the factors regulating cell differentiation in multi-cellular organisms are quite well understood, we are just beginning to unveil the mechanisms underlying individual specialization in cooperative groups of animals. Clonal ants allow the study of which factors influence task allocation without confounding variation in genotype and morphology. Here, we subjected larvae and freshly hatched workers of the clonal ant Platythyrea punctata to different rearing conditions and investigated how these manipulations affected division of labour among pairs of oppositely treated, same-aged clonemates. High rearing temperature, physical stress, injury and malnutrition increased the propensity of individuals to become subordinate foragers rather than dominant reproductives. This is reflected in changed gene regulation: early stages of division of labour were associated with different expression of genes involved in nutrient signalling pathways, metabolism and the phenotypic response to environmental stimuli. Many of these genes appear to be capable of responding to a broad range of stressors. They might link environmental stimuli to behavioural and phenotypic changes and could therefore be more broadly involved in caste differentiation in social insects. Our experiments also shed light on the causes of behavioural variation among genetically identical individuals.

RevDate: 2018-08-14

Heinze S, K Pfeiffer (2018)

Editorial: The Insect Central Complex-From Sensory Coding to Directing Movement.

Frontiers in behavioral neuroscience, 12:156.

RevDate: 2018-08-14

Huebner F, Fichtel C, PM Kappeler (2018)

Linking cognition with fitness in a wild primate: fitness correlates of problem-solving performance and spatial learning ability.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 373(1756):.

Linking the cognitive performance of wild animals with fitness consequences is crucial for understanding evolutionary processes that shape individual variation in cognition. However, the few studies that have examined these links revealed differing relationships between various cognitive performance measures and fitness proxies. To contribute additional comparative data to this body of research, we linked individual performance during repeated problem-solving and spatial learning ability in a maze with body condition and survival in wild grey mouse lemurs (Microcebus murinus). All four variables exhibited substantial inter-individual variation. Solving efficiency in the problem-solving task, but not spatial learning performance, predicted the magnitude of change in body condition after the harsh dry season, indicating that the ability to quickly apply a newly discovered motor technique might also facilitate exploitation of new, natural food resources. Survival was not linked with performance in both tasks, however, suggesting that mouse lemurs' survival might not depend on the cognitive performances addressed here. Our study is the first linking cognition with fitness proxies in a wild primate species, and our discussion highlights the importance and challenges of accounting for a species' life history and ecology in choosing meaningful cognitive and fitness variables for a study in the wild.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.

RevDate: 2018-08-14

Cauchoix M, Chow PKY, van Horik JO, et al (2018)

The repeatability of cognitive performance: a meta-analysis.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 373(1756):.

Behavioural and cognitive processes play important roles in mediating an individual's interactions with its environment. Yet, while there is a vast literature on repeatable individual differences in behaviour, relatively little is known about the repeatability of cognitive performance. To further our understanding of the evolution of cognition, we gathered 44 studies on individual performance of 25 species across six animal classes and used meta-analysis to assess whether cognitive performance is repeatable. We compared repeatability (R) in performance (1) on the same task presented at different times (temporal repeatability), and (2) on different tasks that measured the same putative cognitive ability (contextual repeatability). We also addressed whether R estimates were influenced by seven extrinsic factors (moderators): type of cognitive performance measurement, type of cognitive task, delay between tests, origin of the subjects, experimental context, taxonomic class and publication status. We found support for both temporal and contextual repeatability of cognitive performance, with mean R estimates ranging between 0.15 and 0.28. Repeatability estimates were mostly influenced by the type of cognitive performance measures and publication status. Our findings highlight the widespread occurrence of consistent inter-individual variation in cognition across a range of taxa which, like behaviour, may be associated with fitness outcomes.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.

RevDate: 2018-08-06

Kittler K, Kappeler PM, C Fichtel (2018)

Instrumental problem-solving abilities in three lemur species (Microcebus murinus, Varecia variegata, and Lemur catta).

Journal of comparative psychology (Washington, D.C. : 1983), 132(3):306-314.

Apes and some New and Old World monkeys (i.e., haplorhine primates) are known to routinely use tools. In strepsirrhine primates (i.e., lemurs and lorises), no tool use has been reported, even though they appear to have some basic understanding of the spatial relations required for using a pulling tool. To facilitate direct comparisons of the underlying abilities between haplorhine and strepsirrhine primate species, we experimentally examined instrumental problem-solving abilities in three captive lemur species (Microcebus murinus, Varecia variegata, and Lemur catta), using methods from previous experiments with haplorhine primates. First, lemurs were supposed to use a stick to gain access to an inaccessible food reward. Only one ring-tailed lemur solved this task spontaneously on the first attempt. After offering the stick repeatedly, 13 individuals of all three species solved it successfully. Second, lemurs had to choose between pairs of reachable objects with a food reward on or near them, where one object did not afford pulling in the food. Ring-tailed and gray mouse lemurs generally selected the correct (connected) object, thus performing comparably with haplorhine primates, and ruffed lemurs even matched chimpanzees in their performance. Thus, although strepsirrhine primates may lack the fine motor skills to use a stick as a reaching tool, they performed comparable with naturally tool-using haplorhine primates on means-end problems. Our findings suggest a dissociation in primates between the judgment of spatial relations between two objects, which appears to be roughly equivalent across species, and facility at handling sticks for instrumental purposes, which favors species with enhanced manual dexterity. (PsycINFO Database Record

RevDate: 2018-07-30

Peckre LR, Defolie C, Kappeler PM, et al (2018)

Potential self-medication using millipede secretions in red-fronted lemurs: combining anointment and ingestion for a joint action against gastrointestinal parasites?.

Primates; journal of primatology pii:10.1007/s10329-018-0674-7 [Epub ahead of print].

Self-anointing, referring to the behaviour of rubbing a material object or foreign substance over different parts of the body, has been observed in several vertebrate species, including primates. Several functions, such as detoxifying a rich food source, social communication and protection against ectoparasites, have been proposed to explain this behaviour. Here, we report observations of six wild red-fronted lemurs (Eulemur rufifrons) of both sexes and different age classes anointing their perianal-genital areas and tails with chewed millipedes. Several individuals also ingested millipedes after prolonged chewing. In light of the features of the observed interactions with millipedes, and the nature and potential metabolic pathways of the released chemicals, we suggest a potential self-medicative function. Specifically, we propose that anointing combined with the ingestion of millipedes' benzoquinone secretions by red-fronted lemurs may act in a complementary fashion against gastrointestinal parasite infections, and more specifically Oxyuridae nematodes, providing both prophylactic and therapeutic effects.

RevDate: 2018-07-24

Thamm M, Sturm K, Schlossmann J, et al (2018)

Levels and activity of cGMP-dependent protein kinase in nurse and forager honeybees.

Insect molecular biology [Epub ahead of print].

Age-dependent division of labor in honeybees was shown to be connected to sensory response thresholds. Foragers, show a higher gustatory responsiveness than nurse bees. It is generally assumed that nutrition-related signaling pathways underlie this behavioral plasticity. Here, one important candidate gene is the foraging gene, which encodes a cGMP dependent protein kinase (PKG). Several roles of members of this enzyme family were analyzed in vertebrates. They own functions in important processes such as growth, secretion, and neuronal adaptation. Honeybee foraging mRNA expression is upregulated in the brain of foragers. In vivo activation of PKG can modulate gustatory responsiveness. We present for the first time PKG protein level and activity data in the context of social behavior and feeding. Protein level was significantly higher in forager brains compared to those of nurse bees, substantiating the role of PKG in behavioral plasticity. However, enzyme activity did not differ between behavioral roles. The mediation of feeding status appears independent of PKG signaling. Neither PKG content nor enzyme activity differed between starved and satiated individuals. We suggest that even though nutrition-related pathways are surely involved in controlling behavioral plasticity, which involves changes in PKG signaling, mediation of satiety itself is independent of PKG. This article is protected by copyright. All rights reserved.

RevDate: 2018-07-20
CmpDate: 2018-07-20

Domingue BW, Belsky DW, Fletcher JM, et al (2018)

The social genome of friends and schoolmates in the National Longitudinal Study of Adolescent to Adult Health.

Proceedings of the National Academy of Sciences of the United States of America, 115(4):702-707.

Humans tend to form social relationships with others who resemble them. Whether this sorting of like with like arises from historical patterns of migration, meso-level social structures in modern society, or individual-level selection of similar peers remains unsettled. Recent research has evaluated the possibility that unobserved genotypes may play an important role in the creation of homophilous relationships. We extend this work by using data from 5,500 adolescents from the National Longitudinal Study of Adolescent to Adult Health (Add Health) to examine genetic similarities among pairs of friends. Although there is some evidence that friends have correlated genotypes, both at the whole-genome level as well as at trait-associated loci (via polygenic scores), further analysis suggests that meso-level forces, such as school assignment, are a principal source of genetic similarity between friends. We also observe apparent social-genetic effects in which polygenic scores of an individual's friends and schoolmates predict the individual's own educational attainment. In contrast, an individual's height is unassociated with the height genetics of peers.

RevDate: 2018-07-18

Lichtenstein L, Lichtenstein M, J Spaethe (2018)

Length of stimulus presentation and visual angle are critical for efficient visual PER conditioning in the restrained honey bee, Apis mellifera.

The Journal of experimental biology, 221(Pt 14): pii:221/14/jeb179622.

Learning visual cues is an essential capability of bees for vital behaviors such as orientation in space and recognition of nest sites, food sources and mating partners. To study learning and memory in bees under controlled conditions, the proboscis extension response (PER) provides a well-established behavioral paradigm. While many studies have used the PER paradigm to test olfactory learning in bees because of its robustness and reproducibility, studies on PER conditioning of visual stimuli are rare. In this study, we designed a new setup to test the learning performance of restrained honey bees and the impact of several parameters: stimulus presentation length, stimulus size (i.e. visual angle) and ambient illumination. Intact honey bee workers could successfully discriminate between two monochromatic lights when the color stimulus was presented for 4, 7 and 10 s before a sugar reward was offered, reaching similar performance levels to those for olfactory conditioning. However, bees did not learn at shorter presentation durations. Similar to free-flying honey bees, harnessed bees were able to associate a visual stimulus with a reward at small visual angles (5 deg) but failed to utilize the chromatic information to discriminate the learned stimulus from a novel color. Finally, ambient light had no effect on acquisition performance. We discuss possible reasons for the distinct differences between olfactory and visual PER conditioning.

RevDate: 2018-07-17

Steitz I, Kingwell C, Paxton RJ, et al (2018)

Evolution of Caste-Specific Chemical Profiles in Halictid Bees.

Journal of chemical ecology pii:10.1007/s10886-018-0991-8 [Epub ahead of print].

Chemical communication is crucial for the maintenance of colony organization in eusocial insects and chemical signals are known to mediate important aspects of their social life, including the regulation of reproduction. Sociality is therefore hypothesized to be accompanied by an increase in the complexity of chemical communication. However, little is known about the evolution of odor signals at the transition from solitary living to eusociality. Halictid bees are especially suitable models to study this question as they exhibit considerable variability in social behavior. Here we investigated whether the dissimilarities in cuticle chemical signals in females of different castes and life stages reflect the level of social complexity across halictid bee species. Our hypothesis was that species with a higher social behavior ergo obligate eusocial species possess a more distinct chemical profile between castes or female life stages. We analyzed cuticular chemical profiles of foundresses, breeding females and workers of ancestrally solitary species, facultative and obligate eusocial halictid species. We also tested whether social complexity was associated with a higher investment in chemical signals. Our results revealed higher chemical dissimilarity between castes in obligate than in facultative eusocial species, especially regarding macrocyclic lactones, which were the single common compound class overproduced in queens compared with workers. Chemical dissimilarities were independent of differences in ovarian status in obligate eusocial species but were dependent on ovarian status in facultative eusocial species, which we discuss in an evolutionary framework.

RevDate: 2018-07-19

Arenas A, F Roces (2018)

Appetitive and aversive learning of plants odors inside different nest compartments by foraging leaf-cutting ants.

Journal of insect physiology, 109:85-92 pii:S0022-1910(18)30142-2 [Epub ahead of print].

Cues inside the nest provide social insect foragers with information about resources currently exploited that may influence their decisions outside. Leaf-cutting ants harvest leaf fragments that are either further processed as substrate for their symbiotic fungus, or disposed of if unsuitable. We investigated whether Acromyrmex ambiguus foragers develop learned preferences for olfactory cues they experienced either in the fungus or in the waste chamber of the nest. Foragers' olfactory preferences were quantified as a choice between sugared papers disks scented with a novel odor and with the odor experienced in one of the nest compartments, before and after odor addition. Odors incorporated in the fungus chamber led to preferences towards paper disks smelling of them. Conversely, odors experienced in the waste chambers led to avoidance of similarly-scented disks. To investigate context-specificity of responses, we quantified learned preferences towards an odor that occurred first in the fungus chamber, and 14 h later in the waste chamber. Foragers initially developed a preference for the odor added in the fungus chamber that turned into avoidance when the same odor solely occurred later in the waste chamber. Avoidance of plants could also be induced in a more natural context, when fresh leaf disks of novel plants, privet or firethorn, were presented in the waste chamber. We conclude that learned acceptance or rejection of suitable plants by foragers depend on the learning context: smells can lead to appetitive learning when present in the fungus garden, or to avoidance learning when they occur at the dump.

RevDate: 2018-07-19

Zanni V, Değirmenci L, Annoscia D, et al (2018)

The reduced brood nursing by mite-infested honey bees depends on their accelerated behavioral maturation.

Journal of insect physiology, 109:47-54 pii:S0022-1910(18)30079-9 [Epub ahead of print].

The parasitic mite Varroa destructor is regarded as the most important parasite of honey bees and plays a fundamental role in the decline of bee colonies observed in the last decade in the Northern hemisphere. Parasitization has a number of detrimental effects on bees, including reduced nursing, which can have important impacts on colony balance. In this work we investigated at the individual level the causes of this abnormal behavior and found that the reduced nursing activity in mite-infested workers is associated with impaired learning performance and a series of physiological traits that are typical of foragers, including reduced response to brood pheromone, limited development of hypopharyngeal glands and higher juvenile hormone titre in the haemolymph. Altogether our data confirm the premature transition to foraging already postulated based on previous genomics studies, from a physiological point of view.

RevDate: 2018-06-21

Shibasaki S, M Shimada (2018)

Cyclic dominance emerges from the evolution of two inter-linked cooperative behaviours in the social amoeba.

Proceedings. Biological sciences, 285(1881):.

Evolution of cooperation has been one of the most important problems in sociobiology, and many researchers have revealed mechanisms that can facilitate the evolution of cooperation. However, most studies deal only with one cooperative behaviour, even though some organisms perform two or more cooperative behaviours. The social amoeba Dictyostelium discoideum performs two cooperative behaviours in starvation: fruiting body formation and macrocyst formation. Here, we constructed a model that couples these two behaviours, and we found that the two behaviours are maintained because of the emergence of cyclic dominance, although cooperation cannot evolve if only either of the two behaviours is performed. The common chemoattractant cyclic adenosine 3',5'-monophosphate (cAMP) is used in both fruiting body formation and macrocyst formation, providing a biological context for this coupling. Cyclic dominance emerges regardless of the existence of mating types or spatial structure in the model. In addition, cooperation can re-emerge in the population even after it goes extinct. These results indicate that the two cooperative behaviours of the social amoeba are maintained because of the common chemical signal that underlies both fruiting body formation and macrocyst formation. We demonstrate the importance of coupling multiple games when the underlying behaviours are associated with one another.

RevDate: 2018-06-19

French AS, K Pfeiffer (2018)

Nonlinearization: naturalistic stimulation and nonlinear dynamic behavior in a spider mechanoreceptor.

Biological cybernetics pii:10.1007/s00422-018-0763-0 [Epub ahead of print].

In a previous study, we used linear frequency response analysis to show that naturalistic stimulation of spider primary mechanosensory neurons produced different response dynamics than the commonly used Gaussian random noise. We isolated this difference to the production of action potentials from receptor potential and suggested that the different distribution of frequency components in the naturalistic signal increased the nonlinearity of action potential encoding. Here, we tested the relative contributions of first- and second-order processes to the action potential signal by measuring linear and quadratic coherence functions. Naturalistic stimulation shifted the linear coherence toward lower frequencies, while quadratic coherence was always higher than linear coherence and increased with naturalistic stimulation. In an initial attempt to separate the order of time-dependent and nonlinear processes, we fitted quadratic frequency response functions by two block-structured models consisting of a power-law filter and a static second-order nonlinearity in alternate cascade orders. The same cascade models were then fitted to the original time domain data by conventional numerical analysis algorithms, using a polynomial function as the static nonlinearity. Quadratic models with a linear filter followed by a static nonlinearity were favored over the reverse order, but with weak significance. Polynomial nonlinear functions indicated that rectification is a major nonlinearity. A complete quantitative description of sensory encoding in these primary mechanoreceptors remains elusive but clearly requires quadratic and higher nonlinear operations on the input signal to explain the sensitivity of dynamic behavior to different input signal patterns.

RevDate: 2018-06-07

Martin SJ, Correia-Oliveira ME, Shemilt S, et al (2018)

Is the Salivary Gland Associated with Honey Bee Recognition Compounds in Worker Honey Bees (Apis mellifera)?.

Journal of chemical ecology pii:10.1007/s10886-018-0975-8 [Epub ahead of print].

Cuticular hydrocarbons (CHCs) function as recognition compounds with the best evidence coming from social insects such as ants and honey bees. The major exocrine gland involved in hydrocarbon storage in ants is the post-pharyngeal gland (PPG) in the head. It is still not clearly understood where CHCs are stored in the honey bee. The aim of this study was to investigate the hydrocarbons and esters found in five major worker honey bee (Apis mellifera) exocrine glands, at three different developmental stages (newly emerged, nurse, and forager) using a high temperature GC analysis. We found the hypopharyngeal gland contained no hydrocarbons nor esters, and the thoracic salivary and mandibular glands only contained trace amounts of n-alkanes. However, the cephalic salivary gland (CSG) contained the greatest number and highest quantity of hydrocarbons relative to the five other glands with many of the hydrocarbons also found in the Dufour's gland, but at much lower levels. We discovered a series of oleic acid wax esters that lay beyond the detection of standard GC columns. As a bee's activities changed, as it ages, the types of compounds detected in the CSG also changed. For example, newly emerged bees have predominately C19-C23n-alkanes, alkenes and methyl-branched compounds, whereas the nurses' CSG had predominately C31:1 and C33:1 alkene isomers, which are replaced by a series of oleic acid wax esters in foragers. These changes in the CSG were mirrored by corresponding changes in the adults' CHCs profile. This indicates that the CSG may have a parallel function to the PPG found in ants acting as a major storage gland of CHCs. As the CSG duct opens into the buccal cavity the hydrocarbons can be worked into the comb wax and could help explain the role of comb wax in nestmate recognition experiments.

RevDate: 2018-06-02

Villalta I, Abril S, Cerdá X, et al (2018)

Queen Control or Queen Signal in Ants: What Remains of the Controversy 25 Years After Keller and Nonacs' Seminal Paper?.

Journal of chemical ecology pii:10.1007/s10886-018-0974-9 [Epub ahead of print].

Ant queen pheromones (QPs) have long been known to affect colony functioning. In many species, QPs affect important reproductive functions such as diploid larvae sexualization and egg-laying by workers, unmated queens (gynes), or other queens. Until the 1990s, these effects were generally viewed to be the result of queen manipulation through the use of coercive or dishonest signals. However, in their seminal 1993 paper, Keller and Nonacs challenged this idea, suggesting that QPs had evolved as honest signals that informed workers and other colony members of the queen's presence and reproductive state. This paper has greatly influenced the study of ant QPs and inspired numerous attempts to identify fertility-related compounds and test their physiological and behavioral effects. In the present article, we review the literature on ant QPs in various contexts and pay special attention to the role of cuticular hydrocarbons (CHCs). Although the controversy generated by Keller and Nonacs' (Anim Behav 45:787-794, 1993) paper is currently less intensively debated, there is still no clear evidence which allows the rejection of the queen control hypothesis in favor of the queen signal hypothesis. We argue that important questions remain regarding the mode of action of QPs, and their targets which may help understanding their evolution.

RevDate: 2018-07-19

Parijs I, HP Steenackers (2018)

Competitive inter-species interactions underlie the increased antimicrobial tolerance in multispecies brewery biofilms.

The ISME journal, 12(8):2061-2075.

Genetic diversity often enhances the tolerance of microbial communities against antimicrobial treatment. However the sociobiology underlying this antimicrobial tolerance remains largely unexplored. Here we analyze how inter-species interactions can increase antimicrobial tolerance. We apply our approach to 17 industrially relevant multispecies biofilm models, based on species isolated from 58 contaminating biofilms in three breweries. Sulfathiazole was used as antimicrobial agent because it showed the highest activity out of 22 biofilm inhibitors tested. Our analysis reveals that competitive interactions dominate among species within brewery biofilms. We show that antimicrobial treatment can reduce the level of competition and therefore cause a subset of species to bloom. The result is a 1.2-42.7-fold lower percentage inhibition of these species and increased overall tolerance. In addition, we show that the presence of Raoultella can also directly enhance the inherent tolerance of Pseudomonas to antimicrobial treatment, either because the species protect each other or because they induce specific tolerance phenotypes as a response to competitors. Overall, our study emphasizes that the dominance of competitive interactions is central to the enhanced antimicrobial tolerance of the multispecies biofilms, and that the activity of antimicrobials against multispecies biofilms cannot be predicted based on their effect against monocultures.

RevDate: 2018-06-05

Römer D, Bollazzi M, F Roces (2018)

Carbon dioxide sensing in the social context: Leaf-cutting ants prefer elevated CO2 levels to tend their brood.

Journal of insect physiology, 108:40-47.

Social insects show temperature and humidity preferences inside their nests to successfully rear brood. In underground nests, ants also encounter rising CO2 concentrations with increasing depth. It is an open question whether they use CO2 as a cue to decide where to place and tend the brood. Leaf-cutting ants do show CO2 preferences for the culturing of their symbiotic fungus. We evaluated their CO2 choices for brood placement in laboratory experiments. Workers of Acromyrmex lundii in the process of relocating brood were offered a binary choice consisting of two interconnected chambers with different CO2 concentrations. Values ranged from atmospheric to high concentrations of 4% CO2. The CO2 preferences shown by workers for themselves and for brood placement were assessed by quantifying the number of workers and relocated brood in each chamber. Ants showed clear CO2 preferences for brood placement. They avoided atmospheric levels, 1% and 4% CO2, and showed a preference for levels of 3%. This is the first report of CO2 preferences for the maintenance of brood in social insects. The observed preferences for brood location were independent of the workers' own CO2 preferences, since they showed no clear-cut pattern. Workers' CO2 preferences for brood maintenance were slightly higher than those reported for fungus culturing, although brood is reared in the same chambers as the fungus in leaf-cutting ant nests. Workers' choices for brood placement in natural nests are likely the result of competing preferences for other environmental factors more crucial for brood survival, aside from those for CO2.

RevDate: 2018-05-02

Beetz MJ, García-Rosales F, Kössl M, et al (2018)

Robustness of cortical and subcortical processing in the presence of natural masking sounds.

Scientific reports, 8(1):6863 pii:10.1038/s41598-018-25241-x.

Processing of ethologically relevant stimuli could be interfered by non-relevant stimuli. Animals have behavioral adaptations to reduce signal interference. It is largely unexplored whether the behavioral adaptations facilitate neuronal processing of relevant stimuli. Here, we characterize behavioral adaptations in the presence of biotic noise in the echolocating bat Carollia perspicillata and we show that the behavioral adaptations could facilitate neuronal processing of biosonar information. According to the echolocation behavior, bats need to extract their own signals in the presence of vocalizations from conspecifics. With playback experiments, we demonstrate that C. perspicillata increases the sensory acquisition rate by emitting groups of echolocation calls when flying in noisy environments. Our neurophysiological results from the auditory midbrain and cortex show that the high sensory acquisition rate does not vastly increase neuronal suppression and that the response to an echolocation sequence is partially preserved in the presence of biosonar signals from conspecifics.

RevDate: 2018-05-08

Fleischmann PN, Grob R, Müller VL, et al (2018)

The Geomagnetic Field Is a Compass Cue in Cataglyphis Ant Navigation.

Current biology : CB, 28(9):1440-1444.e2.

Desert ants (Cataglyphis) are famous insect navigators. During their foraging lives, the ants leave their underground colonies for long distances and return to their starting point with fair accuracy [1, 2]. Their incessantly running path integrator provides them with a continually updated home vector [3-5]. Directional input to their path integrator is provided by a visual compass based on celestial cues [6, 7]. However, as path integration is prone to cumulative errors, the ants additionally employ landmark guidance routines [8-11]. At the start of their foraging lives, they acquire the necessary landmark information by performing well-structured learning walks [12, 13], including turns about their vertical body axes [14]. When Cataglyphis noda performs these pirouettes, it always gazes at the nest entrance during the longest of several short stopping phases [14]. As the small nest entrance is not visible, the ants can adjust their gaze direction only by reading out their path integrator. However, recent experiments have shown that, for adjusting the goal-centered gaze directions during learning walks, skylight cues are not required [15]. A most promising remaining compass cue is the geomagnetic field, which is used for orientation in one way or the other by a variety of animal species [16-25]. Here, we show that the gaze directions during the look-back-to-the-nest behavior change in a predictable way to alterations of the horizontal component of the magnetic field. This is the first demonstration that, in insects, a geomagnetic compass cue is both necessary and sufficient for accomplishing a well-defined navigational task.

RevDate: 2018-06-05

Fleischmann PN, Rössler W, R Wehner (2018)

Early foraging life: spatial and temporal aspects of landmark learning in the ant Cataglyphis noda.

Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology, 204(6):579-592.

Within the powerful navigational toolkit implemented in desert ants, path integration and landmark guidance are the key routines. Here, we use cue-conflict experiments to investigate the interplay between these two routines in ants, Cataglyphis noda, which start their foraging careers (novices) with learning walks and are then tested at different stages of experience. During their learning walks, the novices take nest-centered views from various directions around the nest. In the present experiments, these learning walks are spatially restricted by arranging differently sized water moats around the nest entrance and thus, limiting the space available around the nest and the nest-feeder route. First, we show that the ants are able to return to the nest by landmark guidance only when the novices have had enough space around the nest entrance for properly performing their learning walks. Second, in 180° cue-conflict situations between path integration and landmark guidance, path integration dominates in the beginning of foraging life (after completion of the learning walks), but with increasing numbers of visits to a familiar feeder landmark guidance comes increasingly into play.

RevDate: 2018-05-15

Kay J, Menegazzi P, Mildner S, et al (2018)

The Circadian Clock of the Ant Camponotus floridanus Is Localized in Dorsal and Lateral Neurons of the Brain.

Journal of biological rhythms, 33(3):255-271.

The circadian clock of social insects has become a focal point of interest for research, as social insects show complex forms of timed behavior and organization within their colonies. These behaviors include brood care, nest maintenance, foraging, swarming, defense, and many other tasks, of which several require social synchronization and accurate timing. Ants of the genus Camponotus have been shown to display a variety of daily timed behaviors such as the emergence of males from the nest, foraging, and relocation of brood. Nevertheless, circadian rhythms of isolated individuals have been studied in few ant species, and the circadian clock network in the brain that governs such behaviors remains completely uncharacterized. Here we show that isolated minor workers of Camponotus floridanus exhibit temperature overcompensated free-running locomotor activity rhythms under constant darkness. Under light-dark cycles, most animals are active during day and night, with a slight preference for the night. On the neurobiological level, we show that distinct cell groups in the lateral and dorsal brain of minor workers of C. floridanus are immunostained with an antibody against the clock protein Period (PER) and a lateral group additionally with an antibody against the neuropeptide pigment-dispersing factor (PDF). PER abundance oscillates in a daily manner, and PDF-positive neurites invade most parts of the brain, suggesting that the PER/PDF-positive neurons are bona fide clock neurons that transfer rhythmic signals into the relevant brain areas controlling rhythmic behavior.

RevDate: 2018-03-28

Hesselbach H, R Scheiner (2018)

Effects of the novel pesticide flupyradifurone (Sivanto) on honeybee taste and cognition.

Scientific reports, 8(1):4954 pii:10.1038/s41598-018-23200-0.

Due to intensive agriculture honeybees are threatened by various pesticides. The use of one group of them, the neonicotinoids, was recently restricted by the European Union. These chemicals bind to the nicotinic acetylcholine receptor (nAchR) in the honeybee brain. Recently, Bayer AG released a new pesticide by the name of "Sivanto" against sucking insects. It is assumed to be harmless for honeybees, although its active ingredient, flupyradifurone, binds nAchR similar to the neonicotinoids. We investigated if this pesticide affects the taste for sugar and cognitive performance in honeybee foragers. These bees are directly exposed to the pesticide while foraging for pollen or nectar. Our results demonstrate that flupyradifurone can reduce taste and appetitive learning performance in honeybees foraging for pollen and nectar, although only the highest concentration had significant effects. Most likely, honeybee foragers will not be exposed to these high concentrations. Therefore, the appropriate use of this pesticide is considered safe for honeybees, at least with respect to the behaviors studied here.

RevDate: 2018-03-11

Strube-Bloss MF, W Rössler (2018)

Multimodal integration and stimulus categorization in putative mushroom body output neurons of the honeybee.

Royal Society open science, 5(2):171785 pii:rsos171785.

Flowers attract pollinating insects like honeybees by sophisticated compositions of olfactory and visual cues. Using honeybees as a model to study olfactory-visual integration at the neuronal level, we focused on mushroom body (MB) output neurons (MBON). From a neuronal circuit perspective, MBONs represent a prominent level of sensory-modality convergence in the insect brain. We established an experimental design allowing electrophysiological characterization of olfactory, visual, as well as olfactory-visual induced activation of individual MBONs. Despite the obvious convergence of olfactory and visual pathways in the MB, we found numerous unimodal MBONs. However, a substantial proportion of MBONs (32%) responded to both modalities and thus integrated olfactory-visual information across MB input layers. In these neurons, representation of the olfactory-visual compound was significantly increased compared with that of single components, suggesting an additive, but nonlinear integration. Population analyses of olfactory-visual MBONs revealed three categories: (i) olfactory, (ii) visual and (iii) olfactory-visual compound stimuli. Interestingly, no significant differentiation was apparent regarding different stimulus qualities within these categories. We conclude that encoding of stimulus quality within a modality is largely completed at the level of MB input, and information at the MB output is integrated across modalities to efficiently categorize sensory information for downstream behavioural decision processing.

RevDate: 2018-02-20

Qu C, JC Dreher (2018)

Sociobiology: Changing the Dominance Hierarchy.

Current biology : CB, 28(4):R167-R169.

One fundamental question is to understand what neural circuits are involved when social hierarchies are established, maintained and modified. Now, a new study shows that a previously subordinate animal can become dominant after optogenetic stimulation of the dorsomedial prefrontal cortex, demonstrating that this brain region is necessary and sufficient to quickly induce winning during social competitions.

RevDate: 2018-02-14

Luro AB, Igic B, Croston R, et al (2018)

Which egg features predict egg rejection responses in American robins? Replicating Rothstein's (1982) study.

Ecology and evolution, 8(3):1673-1679 pii:ECE33759.

Rothstein (Behavioral Ecology and Sociobiology, 11, 1982, 229) was one of the first comprehensive studies to examine how different egg features influence egg rejection behaviors of avian brood parasite-hosts. The methods and conclusions of Rothstein (1982) laid the foundation for subsequent experimental brood parasitism studies over the past thirty years, but its results have never been evaluated with replication. Here, we partially replicated Rothstein's (1982) experiments using parallel artificial model egg treatments to simulate cowbird (Molothrus ater) parasitism in American robin (Turdus migratorius) nests. We compared our data with those of Rothstein (1982) and confirmed most of its original findings: (1) robins reject model eggs that differ from the appearance of a natural robin egg toward that of a natural cowbird egg in background color, size, and maculation; (2) rejection responses were best predicted by model egg background color; and (3) model eggs differing by two or more features from natural robin eggs were more likely to be rejected than model eggs differing by one feature alone. In contrast with Rothstein's (1982) conclusion that American robin egg recognition is not specifically tuned toward rejection of brown-headed cowbird eggs, we argue that our results and those of other recent studies of robin egg rejection suggest a discrimination bias toward rejection of cowbird eggs. Future work on egg recognition will benefit from utilizing a range of model eggs varying continuously in background color, maculation patterning, and size in combination with avian visual modeling, rather than using model eggs which vary only discretely.

RevDate: 2018-04-30
CmpDate: 2018-04-30

Rakotonirina H, Kappeler PM, C Fichtel (2018)

The role of facial pattern variation for species recognition in red-fronted lemurs (Eulemur rufifrons).

BMC evolutionary biology, 18(1):19 pii:10.1186/s12862-018-1126-0.

BACKGROUND: Species recognition, i.e., the ability to distinguish conspecifics from heterospecifics, plays an essential role in reproduction. The role of facial cues for species recognition has been investigated in several non-human primate species except for lemurs. We therefore investigated the role of facial cues for species recognition in wild red-fronted lemurs (Eulemur rufifrons) at Kirindy Forest. We presented adult red-fronted lemurs pictures of male faces from five species including red-fronted lemurs, three closely related species, white-fronted lemurs (E. albifrons), brown lemurs (E. fulvus), rufous brown lemurs (E. rufus), and genetically more distant red-bellied lemurs (E. rubriventer), occurring in allopatry with the study population. We predicted that red-fronted lemurs respond stronger to conspecific than to heterospecific pictures and that females show stronger responses than males. In addition, if genetic drift has played a role in the evolution of facial color patterns in the members of this genus, we predicted that responses of red-fronted lemurs correlate negatively with the genetic distance to the different species stimuli.

RESULTS: Red-fronted lemurs looked significantly longer at pictures of their own species than at those of heterospecifics. Females spent less time looking at pictures of white-fronted, brown and red-bellied lemurs than males did, but not to pictures of red-bellied lemurs and a control stimulus. Individuals also exhibited sniffing behavior while looking at visual stimuli, and the time spent sniffing was significantly longer for pictures of conspecifics compared to those of heterospecifics. Moreover, the time spent looking and sniffing towards the pictures correlated negatively with the genetic distance between their own species and the species presented as stimulus.

CONCLUSIONS: We conclude that red-fronted lemurs have the ability for species recognition using visual facial cues, which may allow them to avoid costly interbreeding. If so, sexual selection might have influenced the evolution of facial patterns in eulemurs. Since responses also correlated with genetic distance, our findings suggest a potential role of genetic drift as well as sexual selection in influencing the evolution of facial variation in eulemurs. Because study subjects looked and sniffed towards the presented pictures, red-fronted lemurs might have the ability for multi-modal species recognition.

RevDate: 2018-07-10

Lichtenstein L, Grübel K, J Spaethe (2018)

Opsin expression patterns coincide with photoreceptor development during pupal development in the honey bee, Apis mellifera.

BMC developmental biology, 18(1):1 pii:10.1186/s12861-018-0162-8.

BACKGROUND: The compound eyes of insects allow them to catch photons and convert the energy into electric signals. All compound eyes consist of numerous ommatidia, each comprising a fixed number of photoreceptors. Different ommatidial types are characterized by a specific set of photoreceptors differing in spectral sensitivity. In honey bees, males and females possess different ommatidial types forming distinct retinal mosaics. However, data are lacking on retinal ontogeny and the mechanisms by which the eyes are patterned. In this study, we investigated the intrinsic temporal and circadian expression patterns of the opsins that give rise to the ultraviolet, blue and green sensitive photoreceptors, as well as the morphological maturation of the retina during pupal development of honey bees.

RESULTS: qPCR and histological labeling revealed that temporal opsin mRNA expression differs between sexes and correlates with rhabdom elongation during photoreceptor development. In the first half of the pupal stage, when the rhabdoms of the photoreceptors are still short, worker and (dorsal) drone retinae exhibit similar expression patterns with relatively high levels of UV (UVop) and only marginal levels of blue (BLop) and green (Lop1) opsin mRNA. In the second half of pupation, when photoreceptors and rhabdoms elongate, opsin expression in workers becomes dominated by Lop1 mRNA. In contrast, the dorsal drone eye shows high expression levels of UVop and BLop mRNA, whereas Lop1 mRNA level decreases. Interestingly, opsin expression levels increase up to 22-fold during early adult life. We also found evidence that opsin expression in adult bees is under the control of the endogenous clock.

CONCLUSIONS: Our data indicate that the formation of the sex-specific retinal composition of photoreceptors takes place during the second half of the pupal development, and that opsin mRNA expression levels continue to increase in young bees, which stands in contrast to Drosophila, where the highest expression levels are found during the late pupal stage and remain constant in adults. From an evolutionary perspective, we hypothesize that the delayed retinal maturation during the early adult phase is linked to the delayed transition from indoor to outdoor activities in bees, when vision becomes important.

RevDate: 2018-04-23
CmpDate: 2018-04-23

Tucker MA, Böhning-Gaese K, Fagan WF, et al (2018)

Moving in the Anthropocene: Global reductions in terrestrial mammalian movements.

Science (New York, N.Y.), 359(6374):466-469.

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.

RevDate: 2018-03-05
CmpDate: 2018-03-05

Kropf J, W Rössler (2018)

In-situ recording of ionic currents in projection neurons and Kenyon cells in the olfactory pathway of the honeybee.

PloS one, 13(1):e0191425 pii:PONE-D-17-33666.

The honeybee olfactory pathway comprises an intriguing pattern of convergence and divergence: ~60.000 olfactory sensory neurons (OSN) convey olfactory information on ~900 projection neurons (PN) in the antennal lobe (AL). To transmit this information reliably, PNs employ relatively high spiking frequencies with complex patterns. PNs project via a dual olfactory pathway to the mushroom bodies (MB). This pathway comprises the medial (m-ALT) and the lateral antennal lobe tract (l-ALT). PNs from both tracts transmit information from a wide range of similar odors, but with distinct differences in coding properties. In the MBs, PNs form synapses with many Kenyon cells (KC) that encode odors in a spatially and temporally sparse way. The transformation from complex information coding to sparse coding is a well-known phenomenon in insect olfactory coding. Intrinsic neuronal properties as well as GABAergic inhibition are thought to contribute to this change in odor representation. In the present study, we identified intrinsic neuronal properties promoting coding differences between PNs and KCs using in-situ patch-clamp recordings in the intact brain. We found very prominent K+ currents in KCs clearly differing from the PN currents. This suggests that odor coding differences between PNs and KCs may be caused by differences in their specific ion channel properties. Comparison of ionic currents of m- and l-ALT PNs did not reveal any differences at a qualitative level.

RevDate: 2017-12-20

Beetz MJ, Kordes S, García-Rosales F, et al (2017)

Processing of Natural Echolocation Sequences in the Inferior Colliculus of Seba's Fruit Eating Bat, Carollia perspicillata.

eNeuro, 4(6): pii:eN-NWR-0314-17.

For the purpose of orientation, echolocating bats emit highly repetitive and spatially directed sonar calls. Echoes arising from call reflections are used to create an acoustic image of the environment. The inferior colliculus (IC) represents an important auditory stage for initial processing of echolocation signals. The present study addresses the following questions: (1) how does the temporal context of an echolocation sequence mimicking an approach flight of an animal affect neuronal processing of distance information to echo delays? (2) how does the IC process complex echolocation sequences containing echo information from multiple objects (multiobject sequence)? Here, we conducted neurophysiological recordings from the IC of ketamine-anaesthetized bats of the species Carollia perspicillata and compared the results from the IC with the ones from the auditory cortex (AC). Neuronal responses to an echolocation sequence was suppressed when compared to the responses to temporally isolated and randomized segments of the sequence. The neuronal suppression was weaker in the IC than in the AC. In contrast to the cortex, the time course of the acoustic events is reflected by IC activity. In the IC, suppression sharpens the neuronal tuning to specific call-echo elements and increases the signal-to-noise ratio in the units' responses. When presenting multiple-object sequences, despite collicular suppression, the neurons responded to each object-specific echo. The latter allows parallel processing of multiple echolocation streams at the IC level. Altogether, our data suggests that temporally-precise neuronal responses in the IC could allow fast and parallel processing of multiple acoustic streams.

RevDate: 2017-12-19

Grob R, Fleischmann PN, Grübel K, et al (2017)

The Role of Celestial Compass Information in Cataglyphis Ants during Learning Walks and for Neuroplasticity in the Central Complex and Mushroom Bodies.

Frontiers in behavioral neuroscience, 11:226.

Central place foragers are faced with the challenge to learn the position of their nest entrance in its surroundings, in order to find their way back home every time they go out to search for food. To acquire navigational information at the beginning of their foraging career, Cataglyphis noda performs learning walks during the transition from interior worker to forager. These small loops around the nest entrance are repeatedly interrupted by strikingly accurate back turns during which the ants stop and precisely gaze back to the nest entrance-presumably to learn the landmark panorama of the nest surroundings. However, as at this point the complete navigational toolkit is not yet available, the ants are in need of a reference system for the compass component of the path integrator to align their nest entrance-directed gazes. In order to find this directional reference system, we systematically manipulated the skylight information received by ants during learning walks in their natural habitat, as it has been previously suggested that the celestial compass, as part of the path integrator, might provide such a reference system. High-speed video analyses of distinct learning walk elements revealed that even exclusion from the skylight polarization pattern, UV-light spectrum and the position of the sun did not alter the accuracy of the look back to the nest behavior. We therefore conclude that C. noda uses a different reference system to initially align their gaze directions. However, a comparison of neuroanatomical changes in the central complex and the mushroom bodies before and after learning walks revealed that exposure to UV light together with a naturally changing polarization pattern was essential to induce neuroplasticity in these high-order sensory integration centers of the ant brain. This suggests a crucial role of celestial information, in particular a changing polarization pattern, in initially calibrating the celestial compass system.

RevDate: 2018-01-30

Pegel U, Pfeiffer K, U Homberg (2018)

Integration of celestial compass cues in the central complex of the locust brain.

The Journal of experimental biology, 221(Pt 2): pii:jeb.171207.

Many insects rely on celestial compass cues such as the polarization pattern of the sky for spatial orientation. In the desert locust, the central complex (CX) houses multiple sets of neurons, sensitive to the oscillation plane of polarized light and thus probably acts as an internal polarization compass. We investigated whether other sky compass cues like direct sunlight or the chromatic gradient of the sky might contribute to this compass. We recorded from polarization-sensitive CX neurons while an unpolarized green or ultraviolet light spot was moved around the head of the animal. All types of neuron that were sensitive to the plane of polarization (E-vector) above the animal also responded to the unpolarized light spots in an azimuth-dependent way. The tuning to the unpolarized light spots was independent of wavelength, suggesting that the neurons encode solar azimuth based on direct sunlight and not on the sky chromatic gradient. Two cell types represented the natural 90 deg relationship between solar azimuth and zenithal E-vector orientation, providing evidence to suggest that solar azimuth information supports the internal polarization compass. Most neurons showed advances in their tuning to the E-vector and the unpolarized light spots dependent on rotation direction, consistent with anticipatory signaling. The amplitude of responses and its variability were dependent on the level of background firing, possibly indicating different internal states. The integration of polarization and solar azimuth information strongly suggests that besides the polarization pattern of the sky, direct sunlight might be an important cue for sky compass navigation in the locust.

RevDate: 2018-07-10

De Tiège A, Van de Peer Y, Braeckman J, et al (2017)

The sociobiology of genes: the gene's eye view as a unifying behavioural-ecological framework for biological evolution.

History and philosophy of the life sciences, 40(1):6 pii:10.1007/s40656-017-0174-x.

Although classical evolutionary theory, i.e., population genetics and the Modern Synthesis, was already implicitly 'gene-centred', the organism was, in practice, still generally regarded as the individual unit of which a population is composed. The gene-centred approach to evolution only reached a logical conclusion with the advent of the gene-selectionist or gene's eye view in the 1960s and 1970s. Whereas classical evolutionary theory can only work with (genotypically represented) fitness differences between individual organisms, gene-selectionism is capable of working with fitness differences among genes within the same organism and genome. Here, we explore the explanatory potential of 'intra-organismic' and 'intra-genomic' gene-selectionism, i.e., of a behavioural-ecological 'gene's eye view' on genetic, genomic and organismal evolution. First, we give a general outline of the framework and how it complements the-to some extent-still 'organism-centred' approach of classical evolutionary theory. Secondly, we give a more in-depth assessment of its explanatory potential for biological evolution, i.e., for Darwin's 'common descent with modification' or, more specifically, for 'historical continuity or homology with modular evolutionary change' as it has been studied by evolutionary developmental biology (evo-devo) during the last few decades. In contrast with classical evolutionary theory, evo-devo focuses on 'within-organism' developmental processes. Given the capacity of gene-selectionism to adopt an intra-organismal gene's eye view, we outline the relevance of the latter model for evo-devo. Overall, we aim for the conceptual integration between the gene's eye view on the one hand, and more organism-centred evolutionary models (both classical evolutionary theory and evo-devo) on the other.

RevDate: 2017-12-26
CmpDate: 2017-12-26

Halboth F, F Roces (2017)

The construction of ventilation turrets in Atta vollenweideri leaf-cutting ants: Carbon dioxide levels in the nest tunnels, but not airflow or air humidity, influence turret structure.

PloS one, 12(11):e0188162 pii:PONE-D-17-31087.

Nest ventilation in the leaf-cutting ant Atta vollenweideri is driven via a wind-induced mechanism. On their nests, workers construct small turrets that are expected to facilitate nest ventilation. We hypothesized that the construction and structural features of the turrets would depend on the colony's current demands for ventilation and thus might be influenced by the prevailing environmental conditions inside the nest. Therefore, we tested whether climate-related parameters, namely airflow, air humidity and CO2 levels in the outflowing nest air influenced turret construction in Atta vollenweideri. In the laboratory, we simulated a semi-natural nest arrangement with fungus chambers, a central ventilation tunnel providing outflow of air and an aboveground building arena for turret construction. In independent series, different climatic conditions inside the ventilation tunnel were experimentally generated, and after 24 hours, several features of the built turret were quantified, i.e., mass, height, number and surface area (aperture) of turret openings. Turret mass and height were similar in all experiments even when no airflow was provided in the ventilation tunnel. However, elevated CO2 levels led to the construction of a turret with several minor openings and a larger total aperture. This effect was statistically significant at higher CO2 levels of 5% and 10% but not at 1% CO2. The construction of a turret with several minor openings did not depend on the strong differences in CO2 levels between the outflowing and the outside air, since workers also built permeated turrets even when the CO2 levels inside and outside were both similarly high. We propose that the construction of turrets with several openings and larger opening surface area might facilitate the removal of CO2 from the underground nest structure and could therefore be involved in the control of nest climate in leaf-cutting ants.

RevDate: 2017-12-28

Mueller UG, Ishak HD, Bruschi SM, et al (2017)

Biogeography of mutualistic fungi cultivated by leafcutter ants.

Molecular ecology, 26(24):6921-6937.

Leafcutter ants propagate co-evolving fungi for food. The nearly 50 species of leafcutter ants (Atta, Acromyrmex) range from Argentina to the United States, with the greatest species diversity in southern South America. We elucidate the biogeography of fungi cultivated by leafcutter ants using DNA sequence and microsatellite-marker analyses of 474 cultivars collected across the leafcutter range. Fungal cultivars belong to two clades (Clade-A and Clade-B). The dominant and widespread Clade-A cultivars form three genotype clusters, with their relative prevalence corresponding to southern South America, northern South America, Central and North America. Admixture between Clade-A populations supports genetic exchange within a single species, Leucocoprinus gongylophorus. Some leafcutter species that cut grass as fungicultural substrate are specialized to cultivate Clade-B fungi, whereas leafcutters preferring dicot plants appear specialized on Clade-A fungi. Cultivar sharing between sympatric leafcutter species occurs frequently such that cultivars of Atta are not distinct from those of Acromyrmex. Leafcutters specialized on Clade-B fungi occur only in South America. Diversity of Clade-A fungi is greatest in South America, but minimal in Central and North America. Maximum cultivar diversity in South America is predicted by the Kusnezov-Fowler hypothesis that leafcutter ants originated in subtropical South America and only dicot-specialized leafcutter ants migrated out of South America, but the cultivar diversity becomes also compatible with a recently proposed hypothesis of a Central American origin by postulating that leafcutter ants acquired novel cultivars many times from other nonleafcutter fungus-growing ants during their migrations from Central America across South America. We evaluate these biogeographic hypotheses in the light of estimated dates for the origins of leafcutter ants and their cultivars.

RevDate: 2017-12-19

Rakotonirina H, Kappeler PM, C Fichtel (2017)

Evolution of facial color pattern complexity in lemurs.

Scientific reports, 7(1):15181 pii:10.1038/s41598-017-15393-7.

Interspecific variation in facial color patterns across New and Old World primates has been linked to species recognition and group size. Because group size has opposite effects on interspecific variation in facial color patterns in these two radiations, a study of the third large primate radiation may shed light on convergences and divergences in this context. We therefore compiled published social and ecological data and analyzed facial photographs of 65 lemur species to categorize variation in hair length, hair and skin coloration as well as color brightness. Phylogenetically controlled analyses revealed that group size and the number of sympatric species did not influence the evolution of facial color complexity in lemurs. Climatic factors, however, influenced facial color complexity, pigmentation and hair length in a few facial regions. Hair length in two facial regions was also correlated with group size and may facilitate individual recognition. Since phylogenetic signals were moderate to high for most models, genetic drift may have also played a role in the evolution of facial color patterns of lemurs. In conclusion, social factors seem to have played only a subordinate role in the evolution of facial color complexity in lemurs, and, more generally, group size appears to have no systematic functional effect on facial color complexity across all primates.

RevDate: 2017-12-19

Steijven K, Spaethe J, Steffan-Dewenter I, et al (2017)

Learning performance and brain structure of artificially-reared honey bees fed with different quantities of food.

PeerJ, 5:e3858 pii:3858.

BACKGROUND: Artificial rearing of honey bee larvae is an established method which enables to fully standardize the rearing environment and to manipulate the supplied diet to the brood. However, there are no studies which compare learning performance or neuroanatomic differences of artificially-reared (in-lab) bees in comparison with their in-hive reared counterparts.

METHODS: Here we tested how different quantities of food during larval development affect body size, brain morphology and learning ability of adult honey bees. We used in-lab rearing to be able to manipulate the total quantity of food consumed during larval development. After hatching, a subset of the bees was taken for which we made 3D reconstructions of the brains using confocal laser-scanning microscopy. Learning ability and memory formation of the remaining bees was tested in a differential olfactory conditioning experiment. Finally, we evaluated how bees reared with different quantities of artificial diet compared to in-hive reared bees.

RESULTS: Thorax and head size of in-lab reared honey bees, when fed the standard diet of 160 µl or less, were slightly smaller than hive bees. The brain structure analyses showed that artificially reared bees had smaller mushroom body (MB) lateral calyces than their in-hive counterparts, independently of the quantity of food they received. However, they showed the same total brain size and the same associative learning ability as in-hive reared bees. In terms of mid-term memory, but not early long-term memory, they performed even better than the in-hive control.

DISCUSSION: We have demonstrated that bees that are reared artificially (according to the Aupinel protocol) and kept in lab-conditions perform the same or even better than their in-hive sisters in an olfactory conditioning experiment even though their lateral calyces were consistently smaller at emergence. The applied combination of experimental manipulation during the larval phase plus subsequent behavioral and neuro-anatomic analyses is a powerful tool for basic and applied honey bee research.

RevDate: 2018-02-14
CmpDate: 2018-01-02

Charpentier MJE, Givalois L, Faurie C, et al (2018)

Seasonal glucocorticoid production correlates with a suite of small-magnitude environmental, demographic, and physiological effects in mandrills.

American journal of physical anthropology, 165(1):20-33.

OBJECTIVES: The activation of the hypothalamic-pituitary-adrenal axis is a neuroendocrine response to external and internal changes that animals face on a predictable or unpredictable basis. Across species, variation in glucocorticoid production has been related to such changes. In this study, we investigated the predictable, seasonal sources of variation in the levels of fecal glucocorticoid metabolites (fGCM) in a large natural population of mandrills (Mandrillus sphinx) in Southern Gabon.

MATERIALS AND METHODS: Using five years of regular behavioral monitoring and hormone analyses performed on 1,233 fecal samples collected on 99 individuals of both sexes and all ages and General Linear Mixed Models, we studied the three main seasonal predictors of fGCM concentrations: (i) weather conditions, (ii) number of adult males, and (iii) female reproductive status. These three predictors all vary seasonally in mandrills.

RESULTS: We first showed an increase in fGCM concentrations during the short dry season while controlling for other factors. Pregnant females, which include the large majority of adult females at this time of the year, mainly drove this increase, although a combination of other small-magnitude, season-related effects linked to climatic events and demographic changes also partly explained this seasonal trend. Indeed, fGCM concentrations increased with both low temperatures (and low rainfall) and high numbers of adult males present in the group. These seasonal changes, while correlated, held true throughout the studied years and when restricting our analyses to a given season. Finally, we found that older mandrills showed on average higher fGCM concentrations than younger ones and that medium-ranked females exhibited the highest levels of fGCMs.

DISCUSSION: The observed patterns suggest that plasticity in mandrills' metabolism in the form of glucocorticoid production allows them to adjust to predictable changes in climatic, demographic and physiological conditions by mobilizing and redirecting energetic resources toward appropriate, calibrated seasonal responses.

RevDate: 2018-03-20

Levallois C (2017)

The Development of Sociobiology in Relation to Animal Behavior Studies, 1946-1975.

Journal of the history of biology pii:10.1007/s10739-017-9491-x [Epub ahead of print].

This paper aims at bridging a gap between the history of American animal behavior studies and the history of sociobiology. In the post-war period, ecology, comparative psychology and ethology were all investigating animal societies, using different approaches ranging from fieldwork to laboratory studies. We argue that this disunity in "practices of place" (Kohler, Robert E. Landscapes & Labscapes: Exploring the Lab-Field Border in Biology. Chicago: University of Chicago Press, 2002) explains the attempts of dialogue between those three fields and early calls for unity through "sociobiology" by J. Paul Scott. In turn, tensions between the naturalist tradition and the rising reductionist approach in biology provide an original background for a history of Edward Wilson's own version of sociobiology, much beyond the William Hamilton's papers (Journal of Theoretical Biology 7: 1-16, 17-52, 1964) usually considered as its key antecedent. Naturalists were in a defensive position in the geography of the fields studying animal behavior, and in reaction were a driving force behind the various projects of synthesis called "sociobiology".

RevDate: 2018-04-27

Değirmenci L, Thamm M, R Scheiner (2018)

Responses to sugar and sugar receptor gene expression in different social roles of the honeybee (Apis mellifera).

Journal of insect physiology, 106(Pt 1):65-70.

Honeybees (Apis mellifera) are well-known for their sophisticated division of labor with each bee performing sequentially a series of social tasks. Colony organization is largely based on age-dependent division of labor. While bees perform several tasks inside the hive such as caring for brood ("nursing"), cleaning or sealing brood cells or producing honey, older bees leave to colony to collect pollen (proteins) and nectar (carbohydrates) as foragers. The most pronounced behavioral transition occurs when nurse bees become foragers. For both social roles, the detection and evaluation of sugars is decisive for optimal task performance. Nurse bees rely on their gustatory senses to prepare brood food, while foragers evaluate a nectar source before starting to collect food from it. To test whether social organization is related to differential sensing of sugars we compared the taste of nurse bees and foragers for different sugars. Searching for molecular correlates for differences in sugar perception, we further quantified expression of gustatory receptor genes in both behavioral groups. Our results demonstrate that nurse bees and foragers perceive and evaluate different sugars differently. Both groups, however, prefer sucrose over fructose. At least part of the taste differences between social roles could be related to a differential expression of taste receptors in the antennae and brain. Our results suggest that differential expression of sugar receptor genes might be involved in regulating division of labor through nutrition-related signaling pathways.

RevDate: 2018-06-27
CmpDate: 2018-05-14

Yilmaz A, Dyer AG, Rössler W, et al (2017)

Innate colour preference, individual learning and memory retention in the ant Camponotus blandus.

The Journal of experimental biology, 220(Pt 18):3315-3326.

Ants are a well-characterized insect model for the study of visual learning and orientation, but the extent to which colour vision is involved in these tasks remains unknown. We investigated the colour preference, learning and memory retention of Camponotus blandus foragers under controlled laboratory conditions. Our results show that C. blandus foragers exhibit a strong innate preference for ultraviolet (UV, 365 nm) over blue (450 nm) and green (528 nm) wavelengths. The ants can learn to discriminate 365 nm from either 528 nm or 450 nm, independent of intensity changes. However, they fail to discriminate between 450 nm and 528 nm. Modelling of putative colour spaces involving different numbers of photoreceptor types revealed that colour discrimination performance of individual ants is best explained by dichromacy, comprising a short-wavelength (UV) receptor with peak sensitivity at about 360 nm, and a long-wavelength receptor with peak sensitivity between 470 nm and 560 nm. Foragers trained to discriminate blue or green from UV light are able to retain the learned colour information in an early mid-term (e-MTM), late mid-term (l-MTM), early long-term (e-LTM) and late long-term (l-LTM) memory from where it can be retrieved after 1 h, 12 h, 24 h, 3 days and 7 days after training, indicating that colour learning may induce different memory phases in ants. Overall, our results show that ants can use chromatic information in a way that should promote efficient foraging in complex natural environments.

RevDate: 2017-10-16
CmpDate: 2017-10-16

Halboth F, F Roces (2017)

Underground anemotactic orientation in leaf-cutting ants: perception of airflow and experience-dependent choice of airflow direction during digging.

Die Naturwissenschaften, 104(9-10):82 pii:10.1007/s00114-017-1504-2.

Air exchange between the large nests of Atta vollenweideri leaf-cutting ants and the environment strongly relies on a passive, wind-induced ventilation mechanism. Air moves through nest tunnels and airflow direction depends on the location of the tunnel openings on the nest mound. We hypothesized that ants might use the direction of airflow along nest tunnels as orientation cue in the context of climate control, as digging workers might prefer to broaden or to close tunnels with inflowing or outflowing air in order to regulate nest ventilation. To investigate anemotactic orientation in Atta vollenweideri, we first tested the ants' ability to perceive air movements by confronting single workers with airflow stimuli in the range 0 to 20 cm/s. Workers responded to airflow velocities ≥ 2 cm/s, and the number of ants reacting to the stimulus increased with increasing airflow speed. Second, we asked whether digging workers use airflow direction as an orientation cue. Workers were exposed to either inflow or outflow of air while digging in the nest and could subsequently choose between two digging sites providing either inflow or outflow of air, respectively. Workers significantly chose the side with the same airflow direction they experienced before. When no airflow was present during initial digging, workers showed no preference for airflow directions. Workers developed preferences for airflow direction only after previous exposure to a given airflow direction. We suggest that experience-modified anemotaxis might help leaf-cutting ants spatially organize their digging activity inside the nest during tasks related to climate control.

RevDate: 2018-05-14
CmpDate: 2018-05-14

Cabirol A, Brooks R, Groh C, et al (2017)

Experience during early adulthood shapes the learning capacities and the number of synaptic boutons in the mushroom bodies of honey bees (Apis mellifera).

Learning & memory (Cold Spring Harbor, N.Y.), 24(10):557-562 pii:24/10/557.

The honey bee mushroom bodies (MBs) are brain centers required for specific learning tasks. Here, we show that environmental conditions experienced as young adults affect the maturation of MB neuropil and performance in a MB-dependent learning task. Specifically, olfactory reversal learning was selectively impaired following early exposure to an impoverished environment lacking some of the sensory and social interactions present in the hive. In parallel, the overall number of synaptic boutons increased within the MB olfactory neuropil, whose volume remained unaffected. This suggests that experience of the rich in-hive environment promotes MB maturation and the development of MB-dependent learning capacities.

RevDate: 2017-09-17

Gokhale CS, Traulsen A, G Joop (2017)

Social dilemma in the external immune system of the red flour beetle? It is a matter of time.

Ecology and evolution, 7(17):6758-6765 pii:ECE33198.

Sociobiology has revolutionized our understanding of interactions between organisms. Interactions may present a social dilemma where the interests of individual actors do not align with those of the group as a whole. Viewed through a sociobiological lens, nearly all interactions can be described regarding their costs and benefits, and a number of them then resemble a social dilemma. Numerous experimental systems, from bacteria to mammals, have been proposed as models for studying such dilemmas. Here, we make use of the external immune system of the red flour beetle, Tribolium castaneum, to investigate how the experimental duration can affect whether the external secretion comprises a social dilemma or not. Some beetles (secretors) produce a costly quinone-rich external secretion that inhibits microbial growth in the surrounding environment, providing the secretors with direct personal benefits. However, as the antimicrobial secretion acts in the environment of the beetle, it is potentially also advantageous to other beetles (nonsecretors), who avoid the cost of producing the secretion. We test experimentally if the secretion qualifies as a public good. We find that in the short term, costly quinone secretion can be interpreted as a public good presenting a social dilemma where the presence of secretors increases the fitness of the group. In the long run, the benefit to the group of having more secretors vanishes and becomes detrimental to the group. Therefore, in such seminatural environmental conditions, it turns out that qualifying a trait as social can be a matter of timing.

RevDate: 2017-09-17

Eckhardt F, Kappeler PM, C Kraus (2017)

Highly variable lifespan in an annual reptile, Labord's chameleon (Furcifer labordi).

Scientific reports, 7(1):11397 pii:10.1038/s41598-017-11701-3.

Among tetrapods, the current record holder for shortest lifespan is Labord's chameleon, Furcifer labordi. These reptiles from the arid southwest of Madagascar have a reported lifespan of 4-5 months during the annual rainy season and spend the majority of their life (8-9 months) as a developing embryo. This semelparous, annual life history is unique among tetrapods, but only one population (Ranobe) in the southernmost distribution range has been studied. We therefore investigated the potential for environmentally-dependent variability in lifespan in a population in Kirindy Forest, which has a much longer warm rainy season. While no adults were found after March in Ranobe, the disappearance of adults was delayed by several months in Kirindy. Our data also revealed sex-biased mortality, suggesting that females have a longevity advantage. Furthermore, we found that, after an unusually long previous rainy season, one female was capable of surviving until a second breeding season. Keeping F. labordi in cages under ambient conditions demonstrated that also males can also survive until the next season of activity under these conditions. Our study therefore revealed considerable variability in the extreme life history of this tetrapod that is linked to variation in ecological factors.

RevDate: 2018-07-12
CmpDate: 2018-06-29

Garcia JE, Spaethe J, AG Dyer (2017)

The path to colour discrimination is S-shaped: behaviour determines the interpretation of colour models.

Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology, 203(12):983-997.

Most of our current understanding on colour discrimination by animal observers is built on models. These typically set strict limits on the capacity of an animal to discriminate between colour stimuli imposed by physiological characteristics of the visual system and different assumptions about the underlying mechanisms of colour processing by the brain. Such physiologically driven models were not designed to accommodate sigmoidal-type discrimination functions as those observed in recent behavioural experiments. Unfortunately, many of the fundamental assumptions on which commonly used colour models are based have been tested against empirical data for very few species and many colour vision studies solely rely on physiological measurements of these species for predicting colour discrimination processes. Here, we test the assumption of a universal principle of colour discrimination only mediated by physiological parameters using behavioural data from four closely related hymenopteran species, considering two frequently used models. Results indicate that there is not a unique function describing colour discrimination by closely related bee species, and that this process is independent of specific model assumptions; in fact, different models produce comparable results for specific test species if calibrated against behavioural data.

RevDate: 2017-12-22
CmpDate: 2017-11-06

Rakotoniaina JH, Kappeler PM, Kaesler E, et al (2017)

Hair cortisol concentrations correlate negatively with survival in a wild primate population.

BMC ecology, 17(1):30 pii:10.1186/s12898-017-0140-1.

BACKGROUND: Glucocorticoid hormones are known to play a key role in mediating a cascade of physiological responses to social and ecological stressors and can therefore influence animals' behaviour and ultimately fitness. Yet, how glucocorticoid levels are associated with reproductive success or survival in a natural setting has received little empirical attention so far. Here, we examined links between survival and levels of glucocorticoid in a small, short-lived primate, the grey mouse lemur (Microcebus murinus), using for the first time an indicator of long-term stress load (hair cortisol concentration). Using a capture-mark-recapture modelling approach, we assessed the effect of stress on survival in a broad context (semi-annual rates), but also under a specific period of high energetic demands during the reproductive season. We further assessed the power of other commonly used health indicators (body condition and parasitism) in predicting survival outcomes relative to the effect of long-term stress.

RESULTS: We found that high levels of hair cortisol were associated with reduced survival probabilities both at the semi-annual scale and over the reproductive season. Additionally, very good body condition (measured as scaled mass index) was related to increased survival at the semi-annual scale, but not during the breeding season. In contrast, variation in parasitism failed to predict survival.

CONCLUSION: Altogether, our results indicate that long-term increased glucocorticoid levels can be related to survival and hence population dynamics, and suggest differential strength of selection acting on glucocorticoids, body condition, and parasite infection.

RevDate: 2017-09-03

Rössler W, Spaethe J, C Groh (2017)

Pitfalls of using confocal-microscopy based automated quantification of synaptic complexes in honeybee mushroom bodies (response to Peng and Yang 2016).

Scientific reports, 7(1):9786 pii:10.1038/s41598-017-09967-8.

A recent study by Peng and Yang in Scientific Reports using confocal-microscopy based automated quantification of anti-synapsin labeled microglomeruli in the mushroom bodies of honeybee brains reports potentially incorrect numbers of microglomerular densities. Whereas several previous studies using visually supervised or automated counts from confocal images and analyses of serial 3D electron-microscopy data reported consistent numbers of synaptic complexes per volume, Peng and Yang revealed extremely low numbers differing by a factor of 18 or more from those obtained in visually supervised counts, and by a factor 22-180 from numbers in two other studies using automated counts. This extreme discrepancy is especially disturbing as close comparison of raw confocal images of anti-synapsin labeled whole-mount brain preparations are highly similar across these studies. We conclude that these discrepancies may reside in potential misapplication of confocal imaging followed by erroneous use of automated image analysis software. Consequently, the reported microglomerular densities during maturation and after manipulation by insecticides require validation by application of appropriate confocal imaging methods and analyses tools that rely on skilled observers. We suggest several improvements towards more reliable or standardized automated or semi-automated synapse counts in whole mount preparations of insect brains.

RevDate: 2017-09-02

Scheiner R, Entler BV, Barron AB, et al (2017)

The Effects of Fat Body Tyramine Level on Gustatory Responsiveness of Honeybees (Apis mellifera) Differ between Behavioral Castes.

Frontiers in systems neuroscience, 11:55.

Division of labor is a hallmark of social insects. In the honeybee (Apis mellifera) each sterile female worker performs a series of social tasks. The most drastic changes in behavior occur when a nurse bee, who takes care of the brood and the queen in the hive, transitions to foraging behavior. Foragers provision the colony with pollen, nectar or water. Nurse bees and foragers differ in numerous behaviors, including responsiveness to gustatory stimuli. Differences in gustatory responsiveness, in turn, might be involved in regulating division of labor through differential sensory response thresholds. Biogenic amines are important modulators of behavior. Tyramine and octopamine have been shown to increase gustatory responsiveness in honeybees when injected into the thorax, thereby possibly triggering social organization. So far, most of the experiments investigating the role of amines on gustatory responsiveness have focused on the brain. The potential role of the fat body in regulating sensory responsiveness and division of labor has large been neglected. We here investigated the role of the fat body in modulating gustatory responsiveness through tyramine signaling in different social roles of honeybees. We quantified levels of tyramine, tyramine receptor gene expression and the effect of elevating fat body tyramine titers on gustatory responsiveness in both nurse bees and foragers. Our data suggest that elevating the tyramine titer in the fat body pharmacologically increases gustatory responsiveness in foragers, but not in nurse bees. This differential effect of tyramine on gustatory responsiveness correlates with a higher natural gustatory responsiveness of foragers, with a higher tyramine receptor (Amtar1) mRNA expression in fat bodies of foragers and with lower baseline tyramine titers in fat bodies of foragers compared to those of nurse bees. We suggest that differential tyramine signaling in the fat body has an important role in the plasticity of division of labor through changing gustatory responsiveness.

RevDate: 2018-07-10
CmpDate: 2017-12-26

Beros S, Foitzik S, F Menzel (2017)

What are the Mechanisms Behind a Parasite-Induced Decline in Nestmate Recognition in Ants?.

Journal of chemical ecology, 43(9):869-880.

Social insects have developed sophisticated recognition skills to defend their nests against intruders. They do this by aggressively discriminating against non-nestmates with deviant cuticular hydrocarbon (CHC) signatures. Studying nestmate recognition can be challenging as individual insects do not only vary in their discriminatory abilities, but also in their motivation to behave aggressively. To disentangle the influence of signaling and behavioral motivation on nestmate recognition, we investigated the ant Temnothorax nylanderi, where the presence of tapeworm-infected nestmates leads to reduced nestmate recognition among uninfected workers. The parasite-induced decline in nestmate recognition could be caused by higher intra-colonial cue diversity as tapeworm-infected workers are known to exhibit a modified hydrocarbon signature. This in turn may broaden the neuronal template of their nestmates, leading to a higher tolerance towards alien conspecifics. To test this hypothesis, we exchanged infected ants between colonies and analyzed their impact on CHC profiles of uninfected workers. We demonstrate that despite frequent grooming, which should promote the transfer of recognition cues, CHC profiles of uninfected workers neither changed in the presence of tapeworm-infected ants, nor did it increase cue diversity among uninfected nestmates within or between colonies. However, CHC profiles were systematically affected by the removal of nestmates and addition of non-nestmates, independently from the ants' infection status. For example, when non-nestmates were present workers expressed more dimethyl alkanes and higher overall CHC quantities, possibly to achieve a better distinction from non-nestmates. Workers showed clear task-specific profiles with tapeworm-infected workers resembling more closely young nurses than older foragers. Our results show that the parasite-induced decline in nestmate recognition is not due to increased recognition cue diversity or altered CHC profiles of uninfected workers, but behavioral changes might explain tolerance towards intruders.

RevDate: 2018-07-20
CmpDate: 2018-07-20

Jennions M, Székely T, Beissinger SR, et al (2017)

Sex ratios.

Current biology : CB, 27(16):R790-R792.

Jennions et al. introduce the different kinds of sex ratio and their biology.

RevDate: 2018-07-16
CmpDate: 2018-07-16

Bearne LM, Manning VL, Choy E, et al (2017)

Participants' experiences of an Education, self-management and upper extremity eXercise Training for people with Rheumatoid Arthritis programme (EXTRA).

Physiotherapy, 103(4):430-438.

BACKGROUND: The Education, self-management and upper extremity eXercise Training for people with Rheumatoid Arthritis programme (EXTRA) is an individualized, upper limb, home exercise regimen supplemented by four supervised, group sessions, a handbook and exercise dairy which improves upper extremity disability and self-efficacy.

OBJECTIVE AND STUDY DESIGN: This qualitative interview study explored participants' experience of EXTRA to inform development and implementation of EXTRA into practice.

PARTICIPANTS: Adults with Rheumatoid Arthritis who completed EXTRA were purposively sampled to include a range of ages, upper extremity disabilities, self-efficacy for arthritis self-management and attendance at EXTRA sessions.

METHODS: Individual, semi-structured interviews were conducted with a single researcher until data saturation of themes was reached. Interviews were audio-recorded, transcribed verbatim and analysed using thematic analysis.

RESULTS: Twelve participants (10 females; 32 to 87 years) were interviewed. Four overarching themes were identified: (i) empowering self-management; (ii) influence of others and (iii) the challenge of sustaining exercise, which resonate with the Social Cognition Theory, and (iv) refining EXTRA: consistent and personalised.

CONCLUSIONS: EXTRA enhanced participants' confidence to manage their arthritis independently and was adaptable so it could be integrated with other life commitments. Whilst healthcare professionals, peers and family and friends influenced exercise uptake, sustaining exercise was challenging. Participants desired consistent and continuing contact with a familiar physiotherapist (e.g. via follow-up appointments, digital health technologies) which accommodated individual needs (e.g. different venues, session frequency). Implementation of EXTRA needs to appreciate and address these considerations to facilitate success.

RevDate: 2018-02-12
CmpDate: 2018-02-12

Beaulieu M, Benoit L, Abaga S, et al (2017)

Mind the cell: Seasonal variation in telomere length mirrors changes in leucocyte profile.

Molecular ecology, 26(20):5603-5613.

Leucocytes are typically considered as a whole in studies examining telomere dynamics in mammals. Such an approach may be precarious, as leucocytes represent the only nucleated blood cells in mammals, their composition varies temporally, and telomere length differs between leucocyte types. To highlight this limitation, we examined here whether seasonal variation in leucocyte composition was related to variation in telomere length in free-ranging mandrills (Mandrilllus sphinx). We found that the leucocyte profile of mandrills varied seasonally, with lower lymphocyte proportion being observed during the long dry season presumably because of the combined effects of high nematode infection and stress at that time of the year. Interestingly, this low lymphocyte proportion during the long dry season was associated with shorter telomeres. Accordingly, based on longitudinal data, we found that seasonal changes in lymphocyte proportion were reflected by corresponding seasonal variation in telomere length. Overall, these results suggest that variation in lymphocyte proportion in blood can significantly affect telomere measurements in mammals. However, lymphocyte proportion did not entirely explain variation in telomere length. For instance, a lower lymphocyte proportion with age could not fully explain shorter telomeres in older individuals. Overall, our results show that telomere length and leucocyte profile are strongly although imperfectly intertwined, which may obscure the relationship between telomere dynamics and ageing processes in mammals.

RevDate: 2017-08-18

Springer A, Fichtel C, Al-Ghalith GA, et al (2017)

Patterns of seasonality and group membership characterize the gut microbiota in a longitudinal study of wild Verreaux's sifakas (Propithecus verreauxi).

Ecology and evolution, 7(15):5732-5745 pii:ECE33148.

The intestinal microbiota plays a major role in host development, metabolism, and health. To date, few longitudinal studies have investigated the causes and consequences of microbiota variation in wildlife, although such studies provide a comparative context for interpreting the adaptive significance of findings from studies on humans or captive animals. Here, we investigate the impact of seasonality, diet, group membership, sex, age, and reproductive state on gut microbiota composition in a wild population of group-living, frugi-folivorous primates, Verreaux's sifakas (Propithecus verreauxi). We repeatedly sampled 32 individually recognizable animals from eight adjacent groups over the course of two different climatic seasons. We used high-throughput sequencing of the 16S rRNA gene to determine the microbiota composition of 187 fecal samples. We demonstrate a clear pattern of seasonal variation in the intestinal microbiota, especially affecting the Firmicutes-Bacteroidetes ratio, which may be driven by seasonal differences in diet. The relative abundances of certain polysaccharide-fermenting taxa, for example, Lachnospiraceae, were correlated with fruit and fiber consumption. Additionally, group membership influenced microbiota composition independent of season, but further studies are needed to determine whether this pattern is driven by group divergences in diet, social contacts, or genetic factors. In accordance with findings in other wild mammals and primates with seasonally fluctuating food availability, we demonstrate seasonal variation in the microbiota of wild Verreaux's sifakas, which may be driven by food availability. This study adds to mounting evidence that variation in the intestinal microbiota may play an important role in the ability of primates to cope with seasonal variation in food availability.

RevDate: 2017-08-16

Strube-Bloss MF, Grabe V, Hansson BS, et al (2017)

Calcium imaging revealed no modulatory effect on odor-evoked responses of the Drosophila antennal lobe by two populations of inhibitory local interneurons.

Scientific reports, 7(1):7854 pii:10.1038/s41598-017-08090-y.

Although we have considerable knowledge about how odors are represented in the antennal lobe (AL), the insects' analogue to the olfactory bulb, we still do not fully understand how the different neurons in the AL network contribute to the olfactory code. In Drosophila melanogaster we can selectively manipulate specific neuronal populations to elucidate their function in odor processing. Here we silenced the synaptic transmission of two distinct subpopulations of multiglomerular GABAergic local interneurons (LN1 and LN2) using shibire (shi ts) and analyzed their impact on odor-induced glomerular activity at the AL input and output level. We verified that the employed shi ts construct effectively blocked synaptic transmission to the AL when expressed in olfactory sensory neurons. Notably, selective silencing of both LN populations did not significantly affect the odor-evoked activity patterns in the AL. Neither the glomerular input nor the glomerular output activity was modulated in comparison to the parental controls. We therefore conclude that these LN subpopulations, which cover one third of the total LN number, are not predominantly involved in odor identity coding per se. As suggested by their broad innervation patterns and contribution to long-term adaptation, they might contribute to AL-computation on a global and longer time scale.

RevDate: 2017-08-08

El Jundi B (2017)

Insect Navigation: How Flies Keep Track of Their Snack.

Current biology : CB, 27(15):R748-R750.

A new study provides evidence that fruit flies use path integration to maintain proximity to a food source during their local searches.

RevDate: 2018-06-04
CmpDate: 2018-06-04

Shpigler HY, Saul MC, Corona F, et al (2017)

Deep evolutionary conservation of autism-related genes.

Proceedings of the National Academy of Sciences of the United States of America, 114(36):9653-9658.

E. O. Wilson proposed in Sociobiology that similarities between human and animal societies reflect common mechanistic and evolutionary roots. When introduced in 1975, this controversial hypothesis was beyond science's ability to test. We used genomic analyses to determine whether superficial behavioral similarities in humans and the highly social honey bee reflect common molecular mechanisms. Here, we report that gene expression signatures for individual bees unresponsive to various salient social stimuli are significantly enriched for autism spectrum disorder-related genes. These signatures occur in the mushroom bodies, a high-level integration center of the insect brain. Furthermore, our finding of enrichment was unique to autism spectrum disorders; brain gene expression signatures from other honey bee behaviors do not show this enrichment, nor do datasets from other human behavioral and health conditions. These results demonstrate deep conservation for genes associated with a human social pathology and individual differences in insect social behavior, thus providing an example of how comparative genomics can be used to test sociobiological theory.

RevDate: 2018-04-04
CmpDate: 2018-04-04

Kappeler PM (2017)

Sex roles and adult sex ratios: insights from mammalian biology and consequences for primate behaviour.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 372(1729):.

Theoretical models and empirical studies in various taxa have identified important links between variation in sex roles and the number of adult males and females (adult sex ratio (ASR)) in a population. In this review, I examine these relationships in non-human primates. Because most existing theoretical models of the evolution of sex roles focus on the evolutionary origins of sex-biased behaviour, they offer only a general scaffold for predicting variation in sex roles among and within species. I argue that studies examining sex role variation at these more specific levels need to take social organization into account to identify meaningful levels for the measurement of ASR and to account for the fact that ASR and sex roles mutually influence each other. Moreover, taxon-specific life-history traits can constrain sex role flexibility and impact the operational sex ratio (OSR) by specifying the minimum length of female time outs from reproduction. Using examples from the primate literature, I highlight practical problems in estimating ASR and OSR. I then argue that interspecific variation in the occurrence of indirect forms of paternal care might indeed be linked to variation in ASR. Some studies also indicate that female aggression and bonding, as well as components of inter-sexual relationships, are sensitive to variation in ASR. Thus, links between primate sex roles and sex ratios merit further study, and such studies could prompt the development of more specific theoretical models that make realistic assumptions about taxon-specific life history and social organization.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'.

RevDate: 2018-04-04
CmpDate: 2018-04-04

Schacht R, Kramer KL, Székely T, et al (2017)

Adult sex ratios and reproductive strategies: a critical re-examination of sex differences in human and animal societies.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 372(1729):.

It is increasingly recognized that the relative proportion of potential mates to competitors in a population impacts a range of sex-specific behaviours and in particular mating and reproduction. However, while the adult sex ratio (ASR) has long been recognized as an important link between demography and behaviour, this relationship remains understudied. Here, we introduce the first inter-disciplinary collection of research on the causes and consequences of variation in the ASR in human and animal societies. This important topic is relevant to a wide audience of both social and biological scientists due to the central role that the relative number of males to females in a population plays for the evolution of, and contemporary variation in, sex roles across groups, species and higher taxa. The articles in this theme issue cover research on ASR across a variety of taxa and topics. They offer critical re-evaluations of theoretical foundations within both evolutionary and non-evolutionary fields, and propose innovative methodological approaches, present new empirical examples of behavioural consequences of ASR variation and reveal that the ASR plays a major role in determining population viability, especially in small populations and species with labile sex determination. This introductory paper puts the contributions of the theme issue into a broader context, identifies general trends across the literature and formulates directions for future research.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'.

RevDate: 2017-10-13
CmpDate: 2017-08-07

de Miguel-Díez J, López-de-Andrés A, Hernández-Barrera V, et al (2017)

Decreasing incidence and mortality among hospitalized patients suffering a ventilator-associated pneumonia: Analysis of the Spanish national hospital discharge database from 2010 to 2014.

Medicine, 96(30):e7625.

The aim of this study was to describe trends in the incidence and outcomes of ventilator-associated pneumonia (VAP) among hospitalized patients in Spain (2010-2014).This is a retrospective study using the Spanish national hospital discharge database from year 2010 to 2014. We selected all hospital admissions that had an ICD-9-CM code: 997.31 for VAP in any diagnosis position. We analyzed incidence, sociodemographic and clinical characteristics, procedures, pathogen isolations, and hospital outcomes.We identified 9336 admissions with patients suffering a VAP. Incidence rates of VAP decreased significantly over time (from 41.7 cases/100,000 inhabitants in 2010 to 40.55 in 2014). The mean Charlson comorbidity index (CCI) was 1.08 ± 0.98 and it did not change significantly during the study period. The most frequent causative agent was Pseudomonas and there were not significant differences in the isolation of this microorganism over time. Time trend analyses showed a significant decrease in in-hospital mortality (IHM), from 35.74% in 2010 to 32.81% in 2014. Factor associated with higher IHM included male sex, older age, higher CCI, vein or artery occlusion, pulmonary disease, cancer, undergone surgery, emergency room admission, and readmission.This study shows that the incidence of VAP among hospitalized patients has decreased in Spain from 2010 to 2014. The IHM has also decreased over the study period. Further investigations are needed to improve the prevention and control of VAP.

RevDate: 2018-05-23
CmpDate: 2018-03-26

Fleischmann PN, Grob R, Wehner R, et al (2017)

Species-specific differences in the fine structure of learning walk elements in Cataglyphis ants.

The Journal of experimental biology, 220(Pt 13):2426-2435.

Cataglyphis desert ants are famous navigators. Like all central place foragers, they are confronted with the challenge to return home, i.e. relocate an inconspicuous nest entrance in the ground, after their extensive foraging trips. When leaving the underground nest for the first time, desert ants perform a striking behavior, so-called learning walks that are well structured. However, it is still unclear how the ants initially acquire the information needed for sky- and landmark-based navigation, in particular how they calibrate their compass system at the beginning of their foraging careers. Using high-speed video analyses, we show that different Cataglyphis species include different types of characteristic turns in their learning walks. Pirouettes are full or partial rotations (tight turns about the vertical body axis) during which the ants frequently stop and gaze back in the direction of the nest entrance during the longest stopping phases. In contrast, voltes are small walked circles without directed stopping phases. Interestingly, only Cataglyphis ant species living in a cluttered, and therefore visually rich, environment (i.e. C. noda and C. aenescens in southern Greece) perform both voltes and pirouettes. They look back to the nest entrance during pirouettes, most probably to take snapshots of the surroundings. In contrast, C. fortis inhabiting featureless saltpans in Tunisia perform only voltes and do not stop during these turns to gaze back at the nest - even if a set of artificial landmarks surrounds the nest entrance.

RevDate: 2018-03-27
CmpDate: 2018-03-27

Caniglia G (2017)

"How complex and even perverse the real world can be": W.D. Hamilton's early work on social wasps (1964-1968).

Studies in history and philosophy of biological and biomedical sciences, 64:41-52.

William D. Hamilton's name is often connected to important theoretical accomplishments, from the theory of inclusive fitness and kin selection to the so-called Hamilton's rule and the haplodiploidy hypothesis. This article asks: How did Hamilton attempt to test his theory and hypothesis against the complexity of the biological world? The article reconstructs Hamilton's empirical work with social wasps between 1963 and 1968, the years before and after the publication of the groundbreaking "The Genetical Evolution of Social Behavior" in 1964. It points out the centrality of Hamilton's work on wasps and shows how the British scientist attempted to test theories and hypotheses with naturalistic, developmental, and physiological observations as well as, at times, with experimental manipulations. The article offers a new perspective on the history of the scientific understanding of the evolution of social behavior. In contrast to existing narratives, this perspective emphasizes the importance of empirical work-e.g. natural history, physiology, comparative anatomy-which is often obscured by a nearly exclusive focus on theoretical developments in this field.

RevDate: 2017-08-16

Blenau W, Daniel S, Balfanz S, et al (2017)

Dm5-HT2B: Pharmacological Characterization of the Fifth Serotonin Receptor Subtype of Drosophila melanogaster.

Frontiers in systems neuroscience, 11:28.

Serotonin (5-hydroxytryptamine, 5-HT) is an important regulator of physiological and behavioral processes in both protostomes (e.g., insects) and deuterostomes (e.g., mammals). In insects, serotonin has been found to modulate the heart rate and to control secretory processes, development, circadian rhythms, aggressive behavior, as well as to contribute to learning and memory. Serotonin exerts its activity by binding to and activating specific membrane receptors. The clear majority of these receptors belong to the superfamily of G-protein-coupled receptors. In Drosophila melanogaster, a total of five genes have been identified coding for 5-HT receptors. From this family of proteins, four have been pharmacologically examined in greater detail, so far. While Dm5-HT1A, Dm5-HT1B, and Dm5-HT7 couple to cAMP signaling cascades, the Dm5-HT2A receptor leads to Ca2+ signaling in an inositol-1,4,5-trisphosphate-dependent manner. Based on sequence similarity to homologous genes in other insects, a fifth D. melanogaster gene was uncovered coding for a Dm5-HT2B receptor. Knowledge about this receptor's pharmacological properties is very limited. This is quite surprising because Dm5-HT2B has been attributed to distinct physiological functions based on genetic interference with its gene expression. Mutations were described reducing the response of the larval heart to 5-HT, and specific knockdown of Dm5-HT2B mRNA in hemocytes resulted in a higher susceptibility of the flies to bacterial infection. To gain deeper understanding of Dm5-HT2B's pharmacology, we evaluated the receptor's response to a series of established 5-HT receptor agonists and antagonists in a functional cell-based assay. Metoclopramide and mianserin were identified as two potent antagonists that may allow pharmacological interference with Dm5-HT2B signaling in vitro and in vivo.

RevDate: 2018-04-25
CmpDate: 2018-04-25

Nowak MA, McAvoy A, Allen B, et al (2017)

The general form of Hamilton's rule makes no predictions and cannot be tested empirically.

Proceedings of the National Academy of Sciences of the United States of America, 114(22):5665-5670.

Hamilton's rule asserts that a trait is favored by natural selection if the benefit to others, [Formula: see text], multiplied by relatedness, [Formula: see text], exceeds the cost to self, [Formula: see text] Specifically, Hamilton's rule states that the change in average trait value in a population is proportional to [Formula: see text] This rule is commonly believed to be a natural law making important predictions in biology, and its influence has spread from evolutionary biology to other fields including the social sciences. Whereas many feel that Hamilton's rule provides valuable intuition, there is disagreement even among experts as to how the quantities [Formula: see text], [Formula: see text], and [Formula: see text] should be defined for a given system. Here, we investigate a widely endorsed formulation of Hamilton's rule, which is said to be as general as natural selection itself. We show that, in this formulation, Hamilton's rule does not make predictions and cannot be tested empirically. It turns out that the parameters [Formula: see text] and [Formula: see text] depend on the change in average trait value and therefore cannot predict that change. In this formulation, which has been called "exact and general" by its proponents, Hamilton's rule can "predict" only the data that have already been given.

RevDate: 2018-01-16

Boomsma JJ, R Gawne (2018)

Superorganismality and caste differentiation as points of no return: how the major evolutionary transitions were lost in translation.

Biological reviews of the Cambridge Philosophical Society, 93(1):28-54.

More than a century ago, William Morton Wheeler proposed that social insect colonies can be regarded as superorganisms when they have morphologically differentiated reproductive and nursing castes that are analogous to the metazoan germ-line and soma. Following the rise of sociobiology in the 1970s, Wheeler's insights were largely neglected, and we were left with multiple new superorganism concepts that are mutually inconsistent and uninformative on how superorganismality originated. These difficulties can be traced to the broadened sociobiological concept of eusociality, which denies that physical queen-worker caste differentiation is a universal hallmark of superorganismal colonies. Unlike early evolutionary naturalists and geneticists such as Weismann, Huxley, Fisher and Haldane, who set out to explain the acquisition of an unmated worker caste, the goal of sociobiology was to understand the evolution of eusociality, a broad-brush convenience category that covers most forms of cooperative breeding. By lumping a diverse spectrum of social systems into a single category, and drawing attention away from the evolution of distinct quantifiable traits, the sociobiological tradition has impeded straightforward connections between inclusive fitness theory and the major evolutionary transitions paradigm for understanding irreversible shifts to higher organizational complexity. We evaluate the history by which these inconsistencies accumulated, develop a common-cause approach for understanding the origins of all major transitions in eukaryote hierarchical complexity, and use Hamilton's rule to argue that they are directly comparable. We show that only Wheeler's original definition of superorganismality can be unambiguously linked to irreversible evolutionary transitions from context-dependent reproductive altruism to unconditional differentiation of permanently unmated castes in the ants, corbiculate bees, vespine wasps and higher termites. We argue that strictly monogamous parents were a necessary, albeit not sufficient condition for all transitions to superorganismality, analogous to single-zygote bottlenecking being a necessary but not sufficient condition for the convergent origins of complex soma across multicellular eukaryotes. We infer that conflict reduction was not a necessary condition for the origin of any of these major transitions, and conclude that controversies over the status of inclusive fitness theory primarily emanate from the arbitrarily defined sociobiological concepts of superorganismality and eusociality, not from the theory itself.

RevDate: 2018-01-21
CmpDate: 2017-10-10

De Cocker K, De Bourdeaudhuij I, Cardon G, et al (2017)

What are the working mechanisms of a web-based workplace sitting intervention targeting psychosocial factors and action planning?.

BMC public health, 17(1):382 pii:10.1186/s12889-017-4325-5.

BACKGROUND: Office workers demonstrate high levels of sitting on workdays. As sitting is positively associated with adverse health risks in adults, a theory-driven web-based computer-tailored intervention to influence workplace sitting, named 'Start to Stand,' was developed. The intervention was found to be effective in reducing self-reported workplace sitting among Flemish employees. The aim of this study was to investigate through which mechanisms the web-based computer-tailored intervention influenced self-reported workplace sitting.

METHODS: Employees (n = 155) participated in a clustered randomised controlled trial and reported socio-demographics (age, gender, education), work-related (hours at work, employment duration), health-related (weight and height, workplace sitting and physical activity) and psychosocial (knowledge, attitudes, self-efficacy, social support, intention regarding (changing) sitting behaviours) variables at baseline and 1-month follow-up. The product-of-coefficients test of MacKinnon based on multiple linear regression analyses was conducted to examine the mediating role of five psychosocial factors (knowledge, attitudes, self-efficacy, social support, intention). The influence of one self-regulation skill (action planning) in the association between the intervention and self-reported workplace sitting time was investigated via moderation analyses.

RESULTS: The intervention had a positive influence on knowledge (p = 0.040), but none of the psychosocial variables did mediate the intervention effect on self-reported workplace sitting. Action planning was found to be a significant moderator (p < 0.001) as the decrease in self-reported workplace sitting only occurred in the group completing an action plan.

CONCLUSIONS: Future interventions aimed at reducing employees' workplace sitting are suggested to focus on self-regulatory skills and promote action planning when using web-based computer-tailored advice.

TRIAL REGISTRATION: NCT02672215 ; (Archived by WebCite at

RevDate: 2018-04-25
CmpDate: 2018-04-25

Thamm M, Scholl C, Reim T, et al (2017)

Neuronal distribution of tyramine and the tyramine receptor AmTAR1 in the honeybee brain.

The Journal of comparative neurology, 525(12):2615-2631.

Tyramine is an important neurotransmitter, neuromodulator, and neurohormone in insects. In honeybees, it is assumed to have functions in modulating sensory responsiveness and controlling motor behavior. Tyramine can bind to two characterized receptors in honeybees, both of which are coupled to intracellular cAMP pathways. How tyramine acts on neuronal, cellular and circuit levels is unclear. We investigated the spatial brain expression of the tyramine receptor AmTAR1 using a specific antibody. This antibody detects a membrane protein of the expected molecular weight in western blot analysis. In honeybee brains, it labels different structures which process sensory information. Labeling along the antennal nerve, in projections of the dorsal lobe and in the gnathal ganglion suggest that tyramine receptors are involved in modulating gustatory and tactile perception. Furthermore, the ellipsoid body of the central complex and giant synapses in the lateral complex show AmTAR1-like immunoreactivity (AmTAR1-IR), suggesting a role of this receptor in modulating sky-compass information and/or higher sensor-motor control. Additionally, intense signals derive from the mushroom bodies, higher-order integration centers for olfactory, visual, gustatory and tactile information. To investigate whether AmTAR1-expressing brain structures are in vicinity to tyramine releasing sites, a specific tyramine antibody was applied. Tyramine-like labeling was observed in AmTAR1-IR positive structures, although it was sometimes weak and we did not always find a direct match of ligand and receptor. Moreover, tyramine-like immunoreactivity was also found in brain regions without AmTAR1-IR (optic lobes, antennal lobes), indicating that other tyramine-specific receptors may be expressed there.

RevDate: 2018-06-18

Poirotte C, Massol F, Herbert A, et al (2017)

Mandrills use olfaction to socially avoid parasitized conspecifics.

Science advances, 3(4):e1601721 pii:1601721.

The evolutionary transition from a solitary to a social lifestyle entails an elevated parasite cost because the social proximity associated with group living favors parasite transmission. Despite this cost, sociality is widespread in a large range of taxonomic groups. In this context, hosts would be expected to have evolved behavioral mechanisms to reduce the risk of parasite infection. Few empirical studies have focused on the influence of pathogen-mediated selection on the evolution of antiparasitic behavior in wild vertebrates. We report an adaptive functional relationship between parasitism and social behavior in mandrills, associated with evidence that they are able to gauge parasite status of their group members. Using long-term observations, controlled experiments, and chemical analyses, we show that (i) wild mandrills avoid grooming conspecifics infected with orofecally transmitted parasites; (ii) mandrills receive significantly more grooming after treatment that targets these parasites; (iii) parasitism influences the host's fecal odors; and (iv) mandrills selectively avoid fecal material from parasitized conspecifics. These behavioral adaptations reveal that selecting safe social partners may help primates to cope with parasite-mediated costs of sociality and that "behavioral immunity" plays a crucial role in the coevolutionary dynamics between hosts and their parasites.

RevDate: 2018-03-15

Scharf ME, Cai Y, Sun Y, et al (2017)

A meta-analysis testing eusocial co-option theories in termite gut physiology and symbiosis.

Communicative & integrative biology, 10(2):e1295187 pii:1295187.

The termite gut accomplishes key physiologic functions that underlie termite symbiosis and sociality. However, potential candidate functions of the host-symbiont holobiome have not yet been explored across seemingly divergent processes such as digestion, immunity, caste differentiation, and xenobiotic tolerance. This study took a meta-analysis approach for concurrently studying host and symbiont gut metatranscriptome responses of the lower termite Reticulitermes flavipes, which has ancestral characteristics and hosts a diverse mix of eukaryotic and bacterial symbionts. Thirteen treatments were compared from 5 categories (dietary, social, hormonal, immunological, and xenobiotic), revealing 3 main insights. First, each of the 5 tested colonies had distinct magnitudes of transcriptome response, likely as a result of unique symbiont profiles, which highlights the uniqueness of individual termite colonies. Second, after normalization to standardize colony response magnitudes, unique treatment-linked metatranscriptome topologies became apparent. Third, despite colony and topology differences, 4 co-opted master genes emerged that were universally responsive across diverse treatments. These master genes encode host functions related to protein translation and symbiont functions related to protein degradation and pore formation in microbial cell walls. Three of the 4 master genes were from co-evolved protist symbionts, highlighting potentially co-evolved roles for gut symbiota in coordinating functional responses of the collective host-symbiont holobiome. Lastly, for host genes identified, these results provide annotations of recent termite genome sequences. By revealing conserved domain genes, as well as apparent roles for gut symbiota in holobiome regulation, this study provides new insights into co-opted eusocial genes and symbiont roles in termite sociobiology.

RevDate: 2017-11-16
CmpDate: 2017-08-28

Römer D, Bollazzi M, F Roces (2017)

Carbon dioxide sensing in an obligate insect-fungus symbiosis: CO2 preferences of leaf-cutting ants to rear their mutualistic fungus.

PloS one, 12(4):e0174597 pii:PONE-D-16-45571.

Defense against biotic or abiotic stresses is one of the benefits of living in symbiosis. Leaf-cutting ants, which live in an obligate mutualism with a fungus, attenuate thermal and desiccation stress of their partner through behavioral responses, by choosing suitable places for fungus-rearing across the soil profile. The underground environment also presents hypoxic (low oxygen) and hypercapnic (high carbon dioxide) conditions, which can negatively influence the symbiont. Here, we investigated whether workers of the leaf-cutting ant Acromyrmex lundii use the CO2 concentration as an orientation cue when selecting a place to locate their fungus garden, and whether they show preferences for specific CO2 concentrations. We also evaluated whether levels preferred by workers for fungus-rearing differ from those selected for themselves. In the laboratory, CO2 preferences were assessed in binary choices between chambers with different CO2 concentrations, by quantifying number of workers in each chamber and amount of relocated fungus. Leaf-cutting ants used the CO2 concentration as a spatial cue when selecting places for fungus-rearing. A. lundii preferred intermediate CO2 levels, between 1 and 3%, as they would encounter at soil depths where their nest chambers are located. In addition, workers avoided both atmospheric and high CO2 levels as they would occur outside the nest and at deeper soil layers, respectively. In order to prevent fungus desiccation, however, workers relocated fungus to high CO2 levels, which were otherwise avoided. Workers' CO2 preferences for themselves showed no clear-cut pattern. We suggest that workers avoid both atmospheric and high CO2 concentrations not because they are detrimental for themselves, but because of their consequences for the symbiotic partner. Whether the preferred CO2 concentrations are beneficial for symbiont growth remains to be investigated, as well as whether the observed preferences for fungus-rearing influences the ants' decisions where to excavate new chambers across the soil profile.

RevDate: 2018-03-01
CmpDate: 2017-12-18

Jacobs RL, MacFie TS, Spriggs AN, et al (2017)

Novel opsin gene variation in large-bodied, diurnal lemurs.

Biology letters, 13(3):.

Some primate populations include both trichromatic and dichromatic (red-green colour blind) individuals due to allelic variation at the X-linked opsin locus. This polymorphic trichromacy is well described in day-active New World monkeys. Less is known about colour vision in Malagasy lemurs, but, unlike New World monkeys, only some day-active lemurs are polymorphic, while others are dichromatic. The evolutionary pressures underlying these differences in lemurs are unknown, but aspects of species ecology, including variation in activity pattern, are hypothesized to play a role. Limited data on X-linked opsin variation in lemurs make such hypotheses difficult to evaluate. We provide the first detailed examination of X-linked opsin variation across a lemur clade (Indriidae). We sequenced the X-linked opsin in the most strictly diurnal and largest extant lemur, Indri indri, and nine species of smaller, generally diurnal indriids (Propithecus). Although nocturnal Avahi (sister taxon to Propithecus) lacks a polymorphism, at least eight species of diurnal indriids have two or more X-linked opsin alleles. Four rainforest-living taxa-I. indri and the three largest Propithecus species-have alleles not previously documented in lemurs. Moreover, we identified at least three opsin alleles in Indri with peak spectral sensitivities similar to some New World monkeys.

RevDate: 2017-08-30
CmpDate: 2017-08-30

Arenas A, F Roces (2017)

Avoidance of plants unsuitable for the symbiotic fungus in leaf-cutting ants: Learning can take place entirely at the colony dump.

PloS one, 12(3):e0171388 pii:PONE-D-16-39133.

Plants initially accepted by foraging leaf-cutting ants are later avoided if they prove unsuitable for their symbiotic fungus. Plant avoidance is mediated by the waste produced in the fungus garden soon after the incorporation of the unsuitable leaves, as foragers can learn plant odors and cues from the damaged fungus that are both present in the recently produced waste particles. We asked whether avoidance learning of plants unsuitable for the symbiotic fungus can take place entirely at the colony dump. In order to investigate whether cues available in the waste chamber induce plant avoidance in naïve subcolonies, we exchanged the waste produced by subcolonies fed either fungicide-treated privet leaves or untreated leaves and measured the acceptance of untreated privet leaves before and after the exchange of waste. Second, we evaluated whether foragers could perceive the avoidance cues directly at the dump by quantifying the visits of labeled foragers to the waste chamber. Finally, we asked whether foragers learn to specifically avoid untreated leaves of a plant after a confinement over 3 hours in the dump of subcolonies that were previously fed fungicide-treated leaves of that species. After the exchange of the waste chambers, workers from subcolonies that had access to waste from fungicide-treated privet leaves learned to avoid that plant. One-third of the labeled foragers visited the dump. Furthermore, naïve foragers learned to avoid a specific, previously unsuitable plant if exposed solely to cues of the dump during confinement. We suggest that cues at the dump enable foragers to predict the unsuitable effects of plants even if they had never been experienced in the fungus garden.

RevDate: 2017-12-20
CmpDate: 2017-06-16

Ruedenauer FA, Leonhardt SD, Schmalz F, et al (2017)

Separation of different pollen types by chemotactile sensing in Bombus terrestris.

The Journal of experimental biology, 220(Pt 8):1435-1442.

When tasting food, animals rely on chemical and tactile cues, which determine the animal's decision on whether to eat food. As food nutritional composition has enormous consequences for the survival of animals, food items should generally be tasted before they are eaten or collected for later consumption. Even though recent studies have confirmed the importance of, for example, gustatory cues, compared with olfaction only little is known about the representation of chemotactile stimuli at the receptor level (let alone higher brain centers) in animals other than vertebrates. To better understand how invertebrates may process chemotactile cues, we used bumblebees as a model species and combined electroantennographical (EAG) recordings with a novel technique for chemotactile antennal stimulation in bees. The recorded EAG responses to chemotactile stimulation clearly separated volatile compounds by both compound identity and concentration, and could be successfully applied to test the receptor activity evoked by different types of pollen. We found that two different pollen types (apple and almond; which were readily distinguished by bumblebees in a classical conditioning task) evoked significantly distinct neural activity already at the antennal receptor level. Our novel stimulation technique therefore enables investigation of chemotactile sensing, which is highly important for assessing food nutritional quality while foraging. It can further be applied to test other chemosensory behaviors, such as mate or nest mate recognition, or to investigate whether toxic substances, e.g. in pollen, affect neuronal separation of different food types.

RevDate: 2017-12-20
CmpDate: 2017-06-16

Scheiner R, Reim T, Søvik E, et al (2017)

Learning, gustatory responsiveness and tyramine differences across nurse and forager honeybees.

The Journal of experimental biology, 220(Pt 8):1443-1450.

Honeybees are well known for their complex division of labor. Each bee sequentially performs a series of social tasks during its life. The changes in social task performance are linked to gross differences in behavior and physiology. We tested whether honeybees performing different social tasks (nursing versus foraging) would differ in their gustatory responsiveness and associative learning behavior in addition to their daily tasks in the colony. Further, we investigated the role of the biogenic amine tyramine and its receptors in the behavior of nurse bees and foragers. Tyramine is an important insect neurotransmitter, which has long been neglected in behavioral studies as it was believed to only act as the metabolic precursor of the better-known amine octopamine. With the increasing number of characterized tyramine receptors in diverse insects, we need to understand the functions of tyramine on its own account. Our findings suggest an important role for tyramine and its two receptors in regulating honeybee gustatory responsiveness, social organization and learning behavior. Foragers, which were more responsive to gustatory stimuli than nurse bees and performed better in appetitive learning, also differed from nurse bees in their tyramine brain titers and in the mRNA expression of a tyramine receptor in the brain. Pharmacological activation of tyramine receptors increased gustatory responsiveness of nurse bees and foragers and improved appetitive learning in nurse bees. These data suggest that a large part of the behavioral differences between honeybees may be directly linked to tyramine signaling in the brain.

RevDate: 2017-08-11
CmpDate: 2017-08-11

Kadochová Š, Frouz J, F Roces (2017)

Sun Basking in Red Wood Ants Formica polyctena (Hymenoptera, Formicidae): Individual Behaviour and Temperature-Dependent Respiration Rates.

PloS one, 12(1):e0170570 pii:PONE-D-16-45034.

In early spring, red wood ants Formica polyctena are often observed clustering on the nest surface in large numbers basking in the sun. It has been hypothesized that sun-basking behaviour may contribute to nest heating because of both heat carriage into the nest by sun-basking workers, and catabolic heat production from the mobilization of the workers' lipid reserves. We investigated sun-basking behaviour in laboratory colonies of F. polyctena exposed to an artificial heat source. Observations on identified individuals revealed that not all ants bask in the sun. Sun-basking and non-sun-basking workers did not differ in body size nor in respiration rates. The number of sun-basking ants and the number of their visits to the hot spot depended on the temperature of both the air and the hot spot. To investigate whether sun basking leads to a physiological activation linked with increased lipolysis, we measured respiration rates of individual workers as a function of temperature, and compared respiration rates of sun-basking workers before and two days after they were allowed to expose themselves to a heat source over 10 days, at self-determined intervals. As expected for ectothermic animals, respiration rates increased with increasing temperatures in the range 5 to 35°C. However, the respiration rates of sun-basking workers measured two days after a long-term exposure to the heat source were similar to those before sun basking, providing no evidence for a sustained increase of the basal metabolic rates after prolonged sun basking. Based on our measurements, we argue that self-heating of the nest mound in early spring has therefore to rely on alternative heat sources, and speculate that physical transport of heat in the ant bodies may have a significant effect.

RevDate: 2017-08-14
CmpDate: 2017-08-14

Mildner S, F Roces (2017)

Plasticity of Daily Behavioral Rhythms in Foragers and Nurses of the Ant Camponotus rufipes: Influence of Social Context and Feeding Times.

PloS one, 12(1):e0169244 pii:PONE-D-16-11201.

Daily activities within an ant colony need precise temporal organization, and an endogenous clock appears to be essential for such timing processes. A clock drives locomotor rhythms in isolated workers in a number of ant species, but its involvement in activities displayed in the social context is unknown. We compared locomotor rhythms in isolated individuals and behavioral rhythms in the social context of workers of the ant Camponotus rufipes. Both forager and nurse workers exhibited circadian rhythms in locomotor activity under constant conditions, indicating the involvement of an endogenous clock. Activity was mostly nocturnal and synchronized with the 12:12h light-dark-cycle. To evaluate whether rhythmicity was maintained in the social context and could be synchronized with non-photic zeitgebers such as feeding times, daily behavioral activities of single workers inside and outside the nest were quantified continuously over 24 hours in 1656 hours of video recordings. Food availability was limited to a short time window either at day or at night, thus mimicking natural conditions of temporally restricted food access. Most foragers showed circadian foraging behavior synchronized with food availability, either at day or nighttime. When isolated thereafter in single locomotor activity monitors, foragers mainly displayed arrhythmicity. Here, high mortality suggested potential stressful effects of the former restriction of food availability. In contrast, nurse workers showed high overall activity levels in the social context and performed their tasks all around the clock with no circadian pattern, likely to meet the needs of the brood. In isolation, the same individuals exhibited in turn strong rhythmic activity and nocturnality. Thus, endogenous activity rhythms were inhibited in the social context, and timing of daily behaviors was flexibly adapted to cope with task demands. As a similar socially-mediated plasticity in circadian rhythms was already shown in honey bees, the temporal organization in C. rufipes and honey bees appear to share similar basic features.

RevDate: 2017-12-19
CmpDate: 2017-08-18

Tarnita CE (2017)

The ecology and evolution of social behavior in microbes.

The Journal of experimental biology, 220(Pt 1):18-24.

Cooperation has been studied extensively across the tree of life, from eusociality in insects to social behavior in humans, but it is only recently that a social dimension has been recognized and extensively explored for microbes. Research into microbial cooperation has accelerated dramatically and microbes have become a favorite system because of their fast evolution, their convenience as lab study systems and the opportunity for molecular investigations. However, the study of microbes also poses significant challenges, such as a lack of knowledge and an inaccessibility of the ecological context (used here to include both the abiotic and the biotic environment) under which the trait deemed cooperative has evolved and is maintained. I review the experimental and theoretical evidence in support of the limitations of the study of social behavior in microbes in the absence of an ecological context. I discuss both the need and the opportunities for experimental investigations that can inform a theoretical framework able to reframe the general questions of social behavior in a clear ecological context and to account for eco-evolutionary feedback.

RevDate: 2017-04-10

Peichl L, Kaiser A, Rakotondraparany F, et al (2017)

Diversity of photoreceptor arrangements in nocturnal, cathemeral and diurnal Malagasy lemurs.

The Journal of comparative neurology [Epub ahead of print].

The lemurs of Madagascar (Primates: Lemuriformes) are a monophyletic group that has lived in isolation from other primates for about 50 million years. Lemurs have diversified into species with diverse daily activity patterns and correspondingly different visual adaptations. We assessed the arrangements of retinal cone and rod photoreceptors in six nocturnal, three cathemeral and two diurnal lemur species and quantified different parameters in six of the species. The analysis revealed lower cone densities and higher rod densities in the nocturnal than in the cathemeral and diurnal species. The photoreceptor densities in the diurnal Propithecus verreauxi indicate a less "diurnal" retina than found in other diurnal primates. Immunolabeling for cone opsins showed the presence of both middle-to-longwave sensitive (M/L) and shortwave sensitive (S) cones in most species, indicating at least dichromatic color vision. S cones were absent in Allocebus trichotis and Cheirogaleus medius, indicating cone monochromacy. In the Microcebus species, the S cones had an inverse topography with very low densities in the central retina and highest densities in the peripheral retina. The S cones in the other species and the M/L cones in all species had a conventional topography with peak densities in the central area. With the exception of the cathemeral Eulemur species, the eyes of all studied taxa, including the diurnal Propithecus, possessed a tapetum lucidum, a feature only found among nocturnal and crepuscular mammals.

RevDate: 2017-12-14
CmpDate: 2017-12-14

Strube-Bloss MF, Nawrot MP, R Menzel (2016)

Neural correlates of side-specific odour memory in mushroom body output neurons.

Proceedings. Biological sciences, 283(1844):.

Humans and other mammals as well as honeybees learn a unilateral association between an olfactory stimulus presented to one side and a reward. In all of them, the learned association can be behaviourally retrieved via contralateral stimulation, suggesting inter-hemispheric communication. However, the underlying neuronal circuits are largely unknown and neural correlates of across-brain-side plasticity have yet not been demonstrated. We report neural plasticity that reflects lateral integration after side-specific odour reward conditioning. Mushroom body output neurons that did not respond initially to contralateral olfactory stimulation developed a unique and stable representation of the rewarded compound stimulus (side and odour) predicting its value during memory retention. The encoding of the reward-associated compound stimulus is delayed by about 40 ms compared with unrewarded neural activity, indicating an increased computation time for the read-out after lateral integration.

RevDate: 2018-02-21
CmpDate: 2017-09-28

Springer A, Kappeler PM, CL Nunn (2017)

Dynamic vs. static social networks in models of parasite transmission: predicting Cryptosporidium spread in wild lemurs.

The Journal of animal ecology, 86(3):419-433.

Social networks provide an established tool to implement heterogeneous contact structures in epidemiological models. Dynamic temporal changes in contact structure and ranging behaviour of wildlife may impact disease dynamics. A consensus has yet to emerge, however, concerning the conditions in which network dynamics impact model outcomes, as compared to static approximations that average contact rates over longer time periods. Furthermore, as many pathogens can be transmitted both environmentally and via close contact, it is important to investigate the relative influence of both transmission routes in real-world populations. Here, we use empirically derived networks from a population of wild primates, Verreaux's sifakas (Propithecus verreauxi), and simulated networks to investigate pathogen spread in dynamic vs. static social networks. First, we constructed a susceptible-exposed-infected-recovered model of Cryptosporidium spread in wild Verreaux's sifakas. We incorporated social and environmental transmission routes and parameterized the model for two different climatic seasons. Second, we used simulated networks and greater variation in epidemiological parameters to investigate the conditions in which dynamic networks produce larger outbreak sizes than static networks. We found that average outbreak size of Cryptosporidium infections in sifakas was larger when the disease was introduced in the dry season than in the wet season, driven by an increase in home range overlap towards the end of the dry season. Regardless of season, dynamic networks always produced larger average outbreak sizes than static networks. Larger outbreaks in dynamic models based on simulated networks occurred especially when the probability of transmission and recovery were low. Variation in tie strength in the dynamic networks also had a major impact on outbreak size, while network modularity had a weaker influence than epidemiological parameters that determine transmission and recovery. Our study adds to emerging evidence that dynamic networks can change predictions of disease dynamics, especially if the disease shows low transmissibility and a long infectious period, and when environmental conditions lead to enhanced between-group contact after an infectious agent has been introduced.

RevDate: 2018-01-23
CmpDate: 2017-09-01

Reim T, Balfanz S, Baumann A, et al (2017)

AmTAR2: Functional characterization of a honeybee tyramine receptor stimulating adenylyl cyclase activity.

Insect biochemistry and molecular biology, 80:91-100.

The biogenic monoamines norepinephrine and epinephrine regulate important physiological functions in vertebrates. Insects such as honeybees do not synthesize these neuroactive substances. Instead, they employ octopamine and tyramine for comparable physiological functions. These biogenic amines activate specific guanine nucleotide-binding (G) protein-coupled receptors (GPCRs). Based on pharmacological data obtained on heterologously expressed receptors, α- and β-adrenergic-like octopamine receptors are better activated by octopamine than by tyramine. Conversely, GPCRs forming the type 1 tyramine receptor clade (synonymous to octopamine/tyramine receptors) are better activated by tyramine than by octopamine. More recently, receptors were characterized which are almost exclusively activated by tyramine, thus forming an independent type 2 tyramine receptor clade. Functionally, type 1 tyramine receptors inhibit adenylyl cyclase activity, leading to a decrease in intracellular cAMP concentration ([cAMP]i). Type 2 tyramine receptors can mediate Ca2+ signals or both Ca2+ signals and effects on [cAMP]i. We here provide evidence that the honeybee tyramine receptor 2 (AmTAR2), when heterologously expressed in flpTM cells, exclusively causes an increase in [cAMP]i. The receptor displays a pronounced preference for tyramine over octopamine. Its activity can be blocked by a series of established antagonists, of which mianserin and yohimbine are most efficient. The functional characterization of two tyramine receptors from the honeybee, AmTAR1 (previously named AmTYR1) and AmTAR2, which respond to tyramine by changing cAMP levels in opposite direction, is an important step towards understanding the actions of tyramine in honeybee behavior and physiology, particularly in comparison to the effects of octopamine.

RevDate: 2017-05-18
CmpDate: 2017-05-18

Żakowska-Biemans S, Pieniak Z, Gutkowska K, et al (2017)

Beef consumer segment profiles based on information source usage in Poland.

Meat science, 124:105-113.

The main aim of this study was to identify market segments based on consumers' usage of information sources about beef and to investigate whether the use of information sources was associated with the type of information consumers were searching for, factors guiding their decision processes to buy beef and motives related to beef consumption. Data were collected in 2014 through a self-administered survey of 501 regular beef consumers. Three distinct clusters were identified: Enthusiast (38.5%), Conservative (43.1%) and Ultra Conservative (18.4%). This study revealed that culinary and personal sources of information on beef were the most frequently used. Taste, perceived healthiness and suitability to prepare many dishes were reported as primary motives to eat beef. These results show that communication channels such as culinary programs and opportunities provided by the development of labelling systems to guarantee beef quality should be considered when developing policies and strategies to increase beef consumption in Poland.

RevDate: 2017-12-19
CmpDate: 2017-08-09

O'Shea-Wheller TA, Wilson-Aggarwal DK, Edgley DE, et al (2016)

A social mechanism facilitates ant colony emigrations over different distances.

The Journal of experimental biology, 219(Pt 21):3439-3446.

Behavioural responses enable animals to react rapidly to fluctuating environments. In eusocial organisms, such changes are often enacted at the group level, but may be organised in a decentralised fashion by the actions of individuals. However, the contributions of different group members are rarely homogeneous, and there is evidence to suggest that certain 'keystone' individuals are important in shaping collective responses. Accordingly, investigations of the dynamics and structuring of behavioural changes at both the group and individual level are crucial for evaluating the relative influence of different individuals. Here, we examined the composition of tandem running behaviour during colony emigrations in the ant species Temnothorax albipennis Tandem running is modulated in response to emigration distance, with more runs being conducted when a more distant nest site must be reached. We show that certain individuals are highly active in the tandem running process, attempting significantly more work in the task. Contrary to expectations, however, such individuals are in fact no more successful at conducting tandem runs than their less active nest mates. Instead, it seems that when more tandem runs are required, colonies rely on greater recruitment of workers into the process. The implications of our study are that in some cases, even when apparently 'key' individuals exist within a group, their relative contribution to task performance may be far from decisive.

RevDate: 2018-06-29
CmpDate: 2017-12-28

Huchard E, Schliehe-Diecks S, Kappeler PM, et al (2017)

The inbreeding strategy of a solitary primate, Microcebus murinus.

Journal of evolutionary biology, 30(1):128-140.

Inbreeding depression may be common in nature, reflecting either the failure of inbreeding avoidance strategies or inbreeding tolerance when avoidance is costly. The combined assessment of inbreeding risk, avoidance and depression is therefore fundamental to evaluate the inbreeding strategy of a population, that is how individuals respond to the risk of inbreeding. Here, we use the demographic and genetic monitoring of 10 generations of wild grey mouse lemurs (Microcebus murinus), small primates from Madagascar with overlapping generations, to examine their inbreeding strategy. Grey mouse lemurs have retained ancestral mammalian traits, including solitary lifestyle, polygynandry and male-biased dispersal, and may therefore offer a representative example of the inbreeding strategy of solitary mammals. The occurrence of close kin among candidate mates was frequent in young females (~37%, most often the father) and uncommon in young males (~6%) due to male-biased dispersal. However, close kin consistently represented a tiny fraction of candidate mates (< 1%) across age and sex categories. Mating biases favouring partners with intermediate relatedness were detectable in yearling females and adult males, possibly partly caused by avoidance of daughter-father matings. Finally, inbreeding depression, assessed as the effect of heterozygosity on survival, was undetectable using a capture-mark-recapture study. Overall, these results indicate that sex-biased dispersal is a primary inbreeding avoidance mechanism at the population level, and mating biases represent an additional strategy that may mitigate residual inbreeding costs at the individual level. Combined, these mechanisms explain the rarity of inbreeding and the lack of detectable inbreeding depression in this large, genetically diverse population.

RevDate: 2017-06-14
CmpDate: 2017-06-14

Sommerlandt FM, Spaethe J, Rössler W, et al (2016)

Does Fine Color Discrimination Learning in Free-Flying Honeybees Change Mushroom-Body Calyx Neuroarchitecture?.

PloS one, 11(10):e0164386 pii:PONE-D-16-16674.

Honeybees learn color information of rewarding flowers and recall these memories in future decisions. For fine color discrimination, bees require differential conditioning with a concurrent presentation of target and distractor stimuli to form a long-term memory. Here we investigated whether the long-term storage of color information shapes the neural network of microglomeruli in the mushroom body calyces and if this depends on the type of conditioning. Free-flying honeybees were individually trained to a pair of perceptually similar colors in either absolute conditioning towards one of the colors or in differential conditioning with both colors. Subsequently, bees of either conditioning groups were tested in non-rewarded discrimination tests with the two colors. Only bees trained with differential conditioning preferred the previously learned color, whereas bees of the absolute conditioning group, and a stimuli-naïve group, chose randomly among color stimuli. All bees were then kept individually for three days in the dark to allow for complete long-term memory formation. Whole-mount immunostaining was subsequently used to quantify variation of microglomeruli number and density in the mushroom-body lip and collar. We found no significant differences among groups in neuropil volumes and total microglomeruli numbers, but learning performance was negatively correlated with microglomeruli density in the absolute conditioning group. Based on these findings we aim to promote future research approaches combining behaviorally relevant color learning tests in honeybees under free-flight conditions with neuroimaging analysis; we also discuss possible limitations of this approach.

RevDate: 2018-03-13
CmpDate: 2017-12-04

Koch F, Ganzhorn JU, Rothman JM, et al (2017)

Sex and seasonal differences in diet and nutrient intake in Verreaux's sifakas (Propithecus verreauxi).

American journal of primatology, 79(4):1-10.

Fluctuations in food availability are a major challenge faced by primates living in seasonal climates. Variation in food availability can be especially challenging for females, because of the high energetic costs of reproduction. Therefore, females must adapt the particular demands of the different reproductive stages to the seasonal availability of resources. Madagascar has a highly seasonal climate, where food availability can be extremely variable. We investigated the seasonal changes in diet composition, nutrient and energy intake of female and male sifakas (Propithecus verreauxi) in a dry deciduous forest in western Madagascar. We examined how females adjust their diet to different reproductive stages. Seasonality affected the diet of both sexes; particularly in the dry season (Apr-Oct) with low availability of food items, especially fruits, males and females had a reduced nutrient and energy intake compared to the wet season (Nov-Mar) with higher food and fruit availability. The comparison of the diet between sexes in different reproductive stages showed that during the late stage of lactation (Nov-Jan) females had higher food intake, and as a result they had a higher intake of macronutrients (crude protein, fat and non-structured carbohydrates (TNC)) and energy than males. These differences were not present during the pregnancy of females, with both sexes having similar intake of macronutrients and energy during that stage. The increase in the intake of macronutrients observed for females during late lactation could be related to the higher energetic demands of this stage of reproduction. Thus, the observed pattern in the diet indicates that sifaka females are following a capital breeding strategy, whereby females potentially store enough nutrients to cope with the reproduction costs in periods of low food availability.

RevDate: 2017-08-16

Held M, Berz A, Hensgen R, et al (2016)

Microglomerular Synaptic Complexes in the Sky-Compass Network of the Honeybee Connect Parallel Pathways from the Anterior Optic Tubercle to the Central Complex.

Frontiers in behavioral neuroscience, 10:186.

While the ability of honeybees to navigate relying on sky-compass information has been investigated in a large number of behavioral studies, the underlying neuronal system has so far received less attention. The sky-compass pathway has recently been described from its input region, the dorsal rim area (DRA) of the compound eye, to the anterior optic tubercle (AOTU). The aim of this study is to reveal the connection from the AOTU to the central complex (CX). For this purpose, we investigated the anatomy of large microglomerular synaptic complexes in the medial and lateral bulbs (MBUs/LBUs) of the lateral complex (LX). The synaptic complexes are formed by tubercle-lateral accessory lobe neuron 1 (TuLAL1) neurons of the AOTU and GABAergic tangential neurons of the central body's (CB) lower division (TL neurons). Both TuLAL1 and TL neurons strongly resemble neurons forming these complexes in other insect species. We further investigated the ultrastructure of these synaptic complexes using transmission electron microscopy. We found that single large presynaptic terminals of TuLAL1 neurons enclose many small profiles (SPs) of TL neurons. The synaptic connections between these neurons are established by two types of synapses: divergent dyads and divergent tetrads. Our data support the assumption that these complexes are a highly conserved feature in the insect brain and play an important role in reliable signal transmission within the sky-compass pathway.

RevDate: 2018-06-26
CmpDate: 2017-10-12

Dawkins-Moultin L, McDonald A, L McKyer (2016)

Integrating the Principles of Socioecology and Critical Pedagogy for Health Promotion Health Literacy Interventions.

Journal of health communication, 21(sup2):30-35.

While health literacy research has experienced tremendous growth in the last two decades, the field still struggles to devise interventions that lead to lasting change. Most health literacy interventions are at the individual level and focus on resolving clinician-patient communication difficulties. As a result, the interventions use a deficit model that treats health literacy as a patient problem that needs to be fixed or circumvented. We propose that public health health literacy interventions integrate the principles of socioecology and critical pedagogy to develop interventions that build capacity and empower individuals and communities. Socioecology operates on the premise that health outcome is hinged on the interplay between individuals and their environment. Critical pedagogy assumes education is inherently political, and the ultimate goal of education is social change. Integrating these two approaches will provide a useful frame in which to develop interventions that move beyond the individual level.

RevDate: 2018-04-10
CmpDate: 2016-09-22

Rakotoniaina JH, Kappeler PM, Ravoniarimbinina P, et al (2016)

Does habitat disturbance affect stress, body condition and parasitism in two sympatric lemurs?.

Conservation physiology, 4(1):cow034 pii:cow034.

Understanding how animals react to human-induced changes in their environment is a key question in conservation biology. Owing to their potential correlation with fitness, several physiological parameters are commonly used to assess the effect of habitat disturbance on animals' general health status. Here, we studied how two lemur species, the fat-tailed dwarf lemur (Cheirogaleus medius) and the grey mouse lemur (Microcebus murinus), respond to changing environmental conditions by comparing their stress levels (measured as hair cortisol concentration), parasitism and general body condition across four habitats ordered along a gradient of human disturbance at Kirindy Forest, Western Madagascar. These two species previously revealed contrasting responses to human disturbance; whereas M. murinus is known as a resilient species, C. medius is rarely encountered in highly disturbed habitats. However, neither hair cortisol concentrations nor parasitism patterns (prevalence, parasite species richness and rate of multiple infections) and body condition varied across the gradient of anthropogenic disturbance. Our results indicate that the effect of anthropogenic activities at Kirindy Forest is not reflected in the general health status of both species, which may have developed a range of behavioural adaptations to deal with suboptimal conditions. Nonetheless, a difference in relative density among sites suggests that the carrying capacity of disturbed habitat is lower, and both species respond differently to environmental changes, with C. medius being more negatively affected. Thus, even for behaviourally flexible species, extended habitat deterioration could hamper long-term viability of populations.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.


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This is the book that really started the notion of sociobiology. It came out just as I was starting graduate school and the animal-behavior group organized a discussion group around the book. I was very lucky to have my introduction to in-depth academic discourse be centered around such an interesting book. R. Robbins

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Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )