Viewport Size Code:
Login | Create New Account


About | Classical Genetics | Timelines | What's New | What's Hot

About | Classical Genetics | Timelines | What's New | What's Hot


Bibliography Options Menu

Hide Abstracts   |   Hide Additional Links
Long bibliographies are displayed in blocks of 100 citations at a time. At the end of each block there is an option to load the next block.

Bibliography on: Kin Selection

The Electronic Scholarly Publishing Project: Providing world-wide, free access to classic scientific papers and other scholarly materials, since 1993.


ESP: PubMed Auto Bibliography 09 Apr 2020 at 01:44 Created: 

Kin Selection

Wikipedia: Kin selection is the evolutionary strategy that favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. Kin altruism is altruistic behaviour whose evolution is driven by kin selection. Kin selection is an instance of inclusive fitness, which combines the number of offspring produced with the number an individual can produce by supporting others, such as siblings. Charles Darwin discussed the concept of kin selection in his 1859 book, The Origin of Species, where he reflected on the puzzle of sterile social insects, such as honey bees, which leave reproduction to their mothers, arguing that a selection benefit to related organisms (the same "stock") would allow the evolution of a trait that confers the benefit but destroys an individual at the same time. R.A. Fisher in 1930 and J.B.S. Haldane in 1932 set out the mathematics of kin selection, with Haldane famously joking that he would willingly die for two brothers or eight cousins. In 1964, W.D. Hamilton popularised the concept and the major advance in the mathematical treatment of the phenomenon by George R. Price which has become known as "Hamilton's rule". In the same year John Maynard Smith used the actual term kin selection for the first time. According to Hamilton's rule, kin selection causes genes to increase in frequency when the genetic relatedness of a recipient to an actor multiplied by the benefit to the recipient is greater than the reproductive cost to the actor.

Created with PubMed® Query: "kin selection" or "inclusive fitness" NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2020-04-02

Huneman P (2020)

Essay Review: Exploring the Conceptual Foundations of Post-Hamiltonian Evolutionary Biology-Rationality and Evolution of Social Agents : Samir Okasha. Agents and Goals in Evolution. Oxford: Oxford University Press, 2018. 254p. $40. Jonathan Birch. The Philosophy of Social Evolution. Oxford: Oxford University Press, 2017. 266p. $19,74.

Acta biotheoretica pii:10.1007/s10441-020-09380-1 [Epub ahead of print].

Evolutionary theorists often talk as if natural selection were choosing the most adapted traits, or if organisms were deciding to do the most adaptive strategy. Moreover, the payoff of those decisions often depend on what others are doing, and since Hamilton (1964), biologists possess conceptual tools such as kin selection and inclusive fitness to make sense of outcomes of evolution in these contexts, even when they seem unadaptive (such as sterility). The link between selection and adaptation through which selection or organisms can be seen as agents, as well as the scope and nature of Hamiltonian conceptions of social evolution, stimulated many formal elaborations (such as, initially, Fisher's "Fundamental theorem of natural selection"), but also raise major philosophical issues about causation and statistics, and about rationality and adaptation or selection. Two recent philosophy books, Okasha's Agents and goals in evolution, and Birch's Philosophy of social evolution, tackle those question. This essay reflects on them in order to think of those two issues. After having reviewed the books, I try to sketch some philosophical lessons onto which they concur.

RevDate: 2020-03-28

Smith NMA, Yagound B, Remnant EJ, et al (2020)

Paternally-biased gene expression follows kin-selected predictions in female honey bee embryos.

Molecular ecology [Epub ahead of print].

The Kinship Theory of Genomic Imprinting (KTGI) posits that, in species where females mate with multiple males, there is selection for a male to enhance the reproductive success of his offspring at the expense of other males and his mating partner. Reciprocal crosses between honey bee subspecies show parent-of-origin effects for reproductive traits, suggesting that males modify the expression of genes related to female function in their female offspring. This effect is likely to be greater in the Cape honey bee (Apis mellifera capensis), because a male's daughters have the unique ability to produce female offspring that can develop into reproductive workers or the next queen without mating. We generated reciprocal crosses between Capensis and another subspecies and used RNA-seq to identify transcripts that are over- or under-expressed in the embryos, depending on the parental origin of the gene. As predicted, 21 genes showed expression bias towards the Capensis father's allele in colonies with a Capensis father, with no such bias in the reciprocal cross. A further six genes showed a consistent bias towards expression of the father's allele across all eight colonies examined, regardless of the direction of the cross. Consistent with predictions of the KTGI, six of the 21 genes are associated with female reproduction. No gene consistently showed over-expression of the maternal allele.

RevDate: 2020-03-28

Lehmann L, F Rousset (2020)

When Do Individuals Maximize Their Inclusive Fitness?.

The American naturalist, 195(4):717-732.

Adaptation is often described in behavioral ecology as individuals maximizing their inclusive fitness. Under what conditions does this hold, and how does this relate to the gene-centered perspective of adaptation? We unify and extend the literature on these questions to class-structured populations. We demonstrate that the maximization (in the best-response sense) of class-specific inclusive fitness obtains in uninvadable population states (meaning that all deviating mutants become extinct). This defines a genuine actor-centered perspective on adaptation. But this inclusive fitness is assigned to all bearers of a mutant allele in a given class and depends on distributions of demographic and genetic contexts. These distributions, in turn, usually depend on events in previous generations and are thus not under individual control. This prevents, in general, envisioning individuals themselves as autonomous fitness maximizers, each with its own inclusive fitness. For weak selection, however, the dependence on earlier events can be neglected. We then show that each individual in each class appears to maximize its own inclusive fitness when all other individuals exhibit inclusive fitness-maximizing behavior. This defines a genuine individual-centered perspective of adaptation and justifies formally, as a first-order approximation, the long-heralded view of individuals appearing to maximize their own inclusive fitness.

RevDate: 2020-03-26

Gerber L, Connor RC, King SL, et al (2020)

Affiliation history and age similarity predict alliance formation in adult male bottlenose dolphins.

Behavioral ecology : official journal of the International Society for Behavioral Ecology, 31(2):361-370.

Male alliances are an intriguing phenomenon in the context of reproduction since, in most taxa, males compete over an indivisible resource, female fertilization. Adult male bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia, form long-term, multilevel alliances to sequester estrus females. These alliances are therefore critical to male reproductive success. Yet, the long-term processes leading to the formation of such complex social bonds are still poorly understood. To identify the criteria by which male dolphins form social bonds with other males, we adopted a long-term approach by investigating the ontogeny of alliance formation. We followed the individual careers of 59 males for 14 years while they transitioned from adolescence (8-14 years of age) to adulthood (15-21 years old). Analyzing their genetic relationships and social associations in both age groups, we found that the vast majority of social bonds present in adolescence persisted through time. Male associations in early life predict alliance partners as adults. Kinship patterns explained associations during adolescence but not during adulthood. Instead, adult males associated with males of similar age. Our findings suggest that social bonds among peers, rather than kinship, play a central role in the development of adult male polyadic cooperation in dolphins.

RevDate: 2020-03-23

Daniel MJ, RJ Williamson (2020)

Males optimally balance selfish and kin-selected strategies of sexual competition in the guppy.

Nature ecology & evolution pii:10.1038/s41559-020-1152-3 [Epub ahead of print].

Resolving the strategies by which organisms compete for limited resources is key to understanding behavioural and social evolution. When competing for matings, males in many species allocate mating effort preferentially towards higher-quality females. How males balance this against avoiding competition with rival males, who should also prefer high-quality females, is poorly understood. Kin selection theory further complicates these dynamics: males should avoid competition with close relatives especially because of added, indirect fitness costs. However, whether between-male relatedness modulates the intensity of intrasexual competition is equivocal. Here, we develop and test an analytical model describing how males should optimally allocate their mating efforts in response to information about differences in female quality, competitor presence/absence and competitor relatedness. Using freely interacting groups of Trinidadian guppies (Poecilia reticulata), we show concordance between observed and predicted mating effort allocation across all combinations of these factors. Thus, male mating effort is sensitive to variation in female quality, competitor presence and competitor relatedness, which is consistent with a kin-selected strategy of male-male competition. The fit of our model's predictions demonstrates that males integrate assessments of female quality and competitive context in a quantitatively meaningful way, implicating a competitive strategy that has been fine-tuned to maximize inclusive fitness gains.

RevDate: 2020-03-18

Faria GS, A Gardner (2020)

Does kin discrimination promote cooperation?.

Biology letters, 16(3):20190742.

Genetic relatedness is a key driver of the evolution of cooperation. One mechanism that may ensure social partners are genetically related is kin discrimination, in which individuals are able to distinguish kin from non-kin and adjust their behaviour accordingly. However, the impact of kin discrimination upon the overall level of cooperation remains obscure. Specifically, while kin discrimination allows an individual to help more-related social partners over less-related social partners, it is unclear whether and how the population average level of cooperation that is evolutionarily favoured should differ under kin discrimination versus indiscriminate social behaviour. Here, we perform a general mathematical analysis in order to assess whether, when and in which direction kin discrimination changes the average level of cooperation in an evolving population. We find that kin discrimination may increase, decrease or leave unchanged the average level of cooperation, depending upon whether the optimal level of cooperation is a convex, concave or linear function of genetic relatedness. We develop an extension of the classic 'tragedy of the commons' model of cooperation in order to provide an illustration of these results. Our analysis provides a method to guide future research on the evolutionary consequences of kin discrimination.

RevDate: 2020-03-18

Kennedy P, AN Radford (2020)

Sibling quality and the haplodiploidy hypothesis.

Biology letters, 16(3):20190764.

The 'haplodiploidy hypothesis' argues that haplodiploid inheritance in bees, wasps, and ants generates relatedness asymmetries that promote the evolution of altruism by females, who are less related to their offspring than to their sisters ('supersister' relatedness). However, a consensus holds that relatedness asymmetry can only drive the evolution of eusociality if workers can direct their help preferentially to sisters over brothers, either through sex-ratio biases or a pre-existing ability to discriminate sexes among the brood. We show via a kin selection model that a simple feature of insect biology can promote the origin of workers in haplodiploids without requiring either condition. In insects in which females must found and provision new nests, body quality may have a stronger influence on female fitness than on male fitness. If altruism boosts the quality of all larval siblings, sisters may, therefore, benefit more than brothers from receiving the same amount of help. Accordingly, the benefits of altruism would fall disproportionately on supersisters in haplodiploids. Haplodiploid females should be more prone to altruism than diplodiploid females or males of either ploidy when altruism elevates female fitness especially, and even when altruists are blind to sibling sex.

RevDate: 2020-03-17

Tanskanen AO, Danielsbacka M, A Rotkirch (2020)

Grandparental Childcare for Biological, Adopted, and Step-Offspring: Findings From Cross-National Surveys.

Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior, 18(1):1474704920907894.

Based on kin selection theory, amounts of grandparental investment should reflect the probability to share common genes with offspring. Adoption may represent a special case, however, yet grandparental investment in adopted children has previously been both theoretically misconstrued and little investigated. Here, we study for the first time how grandparental childcare provision is distributed between biological, adopted, and step-offspring. Using Generations and Gender Surveys (n = 15,168 adult child-grandmother and 12,193 adult child-grandfather dyads) and the Survey of Health, Ageing, and Retirement in Europe (n = 17,233 grandmother-adult child and 13,000 grandfather-adult child dyads), we find that grandparents were less likely to provide care to stepchildren than to adopted and biological children, but no difference between adopted and biological children. These findings were present in both data sets and for both grandmothers and grandfathers, after several potentially confounding factors were taken into account. The stepchild disadvantage is in line with kin selection theory. The congruent amounts of care provided to adopted and biological children may reflect similar levels of adult-child attachment, selection effects, and greater need in adoptive families, as well as some degree of genetical relatedness in the case of kin adoption. The study provides new evidence of biased kin investments in contemporary societies and stresses the importance of psychological motivation and attachment in evolutionary studies of kin investment.

RevDate: 2020-03-13

Ruf T, C Bieber (2020)

Use of social thermoregulation fluctuates with mast seeding and reproduction in a pulsed resource consumer.

Oecologia pii:10.1007/s00442-020-04627-7 [Epub ahead of print].

Edible dormice (Glis glis) can remain entirely solitary but frequently share sleeping sites with conspecifics in groups of up to 16 adults and yearlings. Here, we analysed grouping behaviour of 4564 marked individuals, captured in a 13-year study in nest boxes in a deciduous forest. We aimed to clarify (i) whether social thermoregulation is the primary cause for group formation and (ii) which factors affect group size and composition. Dormice temporarily formed both mixed and single-sex groups in response to acute cold ambient temperatures, especially those individuals with small body mass. Thus, thermoregulatory huddling appears to be the driving force for group formation in this species. Huddling was avoided-except for conditions of severe cold load-in years of full mast seeding, which is associated with reproduction and high foraging activity. Almost all females remained solitary during reproduction and lactation. Hence, entire populations of dormice switched between predominantly solitary lives in reproductive years to social behaviour in non-reproductive years. Non-social behaviour pointed to costs of huddling in terms of competition for local food resources even when food is generally abundant. The impact of competition was mitigated by a sex ratio that was biased towards males, which avoids sharing of food resources with related females that have extremely high energy demands during lactation. Importantly, dormice preferentially huddled in male-biased groups with litter mates from previous years. The fraction of related individuals increased with group size. Hence, group composition partly offsets the costs of shared food resources via indirect fitness benefits.

RevDate: 2020-03-13

Cleve JV (2020)

Building a synthetic basis for kin selection and evolutionary game theory using population genetics.

Theoretical population biology pii:S0040-5809(20)30015-0 [Epub ahead of print].

RevDate: 2020-03-09

Lehtonen J (2020)

The Price equation and the unity of social evolution theory.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 375(1797):20190362.

The Price equation has been entangled with social evolution theory from the start. It has been used to derive the most general versions of kin selection theory, and Price himself produced a multilevel equation that provides an alternative formulation of social evolution theory, dividing selection into components between and within groups. In this sense, the Price equation forms a basis for both kin and group selection, so often pitted against each other in the literature. Contextual analysis and the neighbour approach are prominent alternatives for analysing group selection. I discuss these four approaches to social evolution theory and their connections to the Price equation, focusing on their similarities and common mathematical structure. Despite different notations and modelling traditions, all four approaches are ultimately linked by a common set of mathematical components, revealing their underlying unity in a transparent way. The Price equation can similarly be used in the derivation of streamlined, weak selection social evolution modelling methods. These weak selection models are practical and powerful methods for constructing models in evolutionary and behavioural ecology; they can clarify the causal structure of models, and can be easily converted between the four social evolution approaches just like their regression counterparts. This article is part of the theme issue 'Fifty years of the Price equation'.

RevDate: 2020-03-03

Criscione CD, van Paridon BJ, Gilleard JS, et al (2020)

Clonemate cotransmission supports a role for kin selection in a puppeteer parasite.

Proceedings of the National Academy of Sciences of the United States of America pii:1922272117 [Epub ahead of print].

Host manipulation by parasites is a fascinating evolutionary outcome, but adaptive scenarios that often accompany even iconic examples in this popular field of study are speculative. Kin selection has been invoked as a means of explaining the evolution of an altruistic-based, host-manipulating behavior caused by larvae of the lancet fluke Dicrocoelium dendriticum in ants. Specifically, cotransmission of larval clonemates from a snail first host to an ant second host is presumed to lead to a puppeteer parasite in the ant's brain that has clonemates in the ant abdomen. Clonal relatedness between the actor (brain fluke) and recipients (abdomen flukes) enables kin selection of the parasite's host-manipulating trait, which facilitates transmission of the recipients to the final host. However, the hypothesis that asexual reproduction in the snail leads to a high abundance of clonemates in the same ant is untested. Clonal relationships between the manipulator in the brain and the nonmanipulators in the abdomen are also untested. We provide empirical data on the lancet fluke's clonal diversity within its ant host. In stark contrast to other trematodes, which do not exhibit the same host-manipulating behavioral trait, the lancet fluke has a high abundance of clonemates. Moreover, our data support existing theory that indicates that the altruistic behavior can evolve even in the presence of multiple clones within the same ant host. Importantly, our analyses conclusively show clonemate cotransmission into ants, and, as such, we find support for kin selection to drive the evolution and maintenance of this iconic host manipulation.

RevDate: 2020-03-02

Kaundal S, Deep A, Kaur G, et al (2020)

Molecular and Biochemical Characterization of YeeF/YezG, a Polymorphic Toxin-Immunity Protein Pair From Bacillus subtilis.

Frontiers in microbiology, 11:95.

Polymorphic toxins are important and widespread elements of bacterial warfare that help in restricting the growth of competitors, aiding kin selection, and shaping the bacterial communities. Although widespread, polymorphic toxin systems (PTS) have been extensively studied in Gram-negative bacteria, there are limited studies describing PTS in Gram-positive bacteria. The present study characterizes YeeF/YezG, a predicted member of a PF04740 family of the polymorphic toxin-immunity system from a Gram-positive bacteria Bacillus subtilis. The expression of the C-terminal toxic domain of YeeF (YeeF-CT) causes growth inhibition and gross morphological changes in Escherichia coli. The observed toxic effects are neutralized by the co-expression of yezG, a gene present downstream of yeeF, confirming YeeF-CT/YezG as a toxin/immunity protein pair. Biochemical and in vivo studies reveal that YeeF-CT causes toxicity due to its non-specific metal-dependent DNase activity. This is different from the previously reported RNase activity from the three B. subtilis toxins belonging to PF04740 family. Isothermal titration calorimetry (ITC) data analysis suggests that YeeF-CT binds YezG with a dissociation constant in the nanomolar range. Analytical ultracentrifugation studies revealed that YeeF-CT forms a homodimer and binds with two molecules of monomeric YezG immunity protein to form a 2:2 stochiometric heterotetrameric complex. Biolayer interferometry and electrophoretic mobility shift assays show that YeeF-CT/YezG/DNA forms a stable ternary complex implicating that YezG is an exosite inhibitor of YeeF-CT. This study extends the molecular targets of the toxins in the PF04740 family and thus, this family of toxins can be broadly classified as nucleases harboring either DNases or RNases activities.

RevDate: 2020-02-28

Stockmaier S, Bolnick DI, Page RA, et al (2020)

Sickness effects on social interactions depend on the type of behaviour and relationship.

The Journal of animal ecology [Epub ahead of print].

(1) Infections can change social behaviour in multiple ways, with profound impacts on pathogen transmission. However, these impacts might depend on the type of behaviour, how sociality as a biological trait is defined (e.g. network degree versus mean edge strength), and the type of social relationship between the interacting individuals. (2) We used the highly social common vampire bat (Desmodus rotundus) to test how an immune challenge by lipopolysaccharide (LPS) injections affects two different social behaviors and three alternate measures of sociality, and whether the LPS effect differs by kinship relationship. (3) Effects of sickness should be lower for social behaviours that bestow greater benefits to inclusive fitness, such as food sharing. As predicted, immune-challenged bats experienced a greater reduction in allogrooming received than food sharing received. (4) Sickness effects might also depend on how a social interaction is defined (e.g. the number of grooming partners versus the duration of grooming events). We predicted that sickness would impact both the number and duration of social encounters, but we only detected a decrease in the number of grooming partners. (5) Finally, sickness effects might vary with social relationship type. We predicted that sickness effects should be smaller for interactions among close kin. As expected, the immune-challenge had smaller effects on mother-offspring interactions. (6) In conclusion, our results highlight the need to explicitly consider how the effects of sickness on social network structure can differ depending on the "who, what, and how" of social interactions, because these factors are likely to influence how sickness behaviour alters pathogen transmission.

RevDate: 2020-02-26

Lobmaier JS, Probst F, Fischbacher U, et al (2020)

Pleasant body odours, but not genetic similarity, influence trustworthiness in a modified trust game.

Scientific reports, 10(1):3388 pii:10.1038/s41598-020-60407-6.

Identifying trustworthy partners is an important adaptive challenge for establishing mutually cooperative relationships. Previous studies have demonstrated a marked relationship between a person's attractiveness and his apparent trustworthiness (beauty premium). Kin selection theory, however, suggests that cues to kinship enhance trustworthiness. Here we directly tested predictions of the beauty premium and kin selection theory by using body odours as cues to trustworthiness. Body odours reportedly portray information about an individuals' genotype at the human leucocyte antigen system (HLA) and thus olfactory cues in body odours serve as a promising means for kin recognition. Ninety men played trust games in which they divided uneven sums of monetary units between two male trustees represented by their body odour and rated each body odour for pleasantness. Half of the odours came from HLA-similar men (suggesting closer kin) and half from HLA dissimilar men (suggesting non-kin). We found that the amount of money the players transferred was not related to HLA-similarity, but to the pleasantness of the trustee's body odour. By showing that people with more pleasant body odours are trusted more than people with unpleasant body odour we provide evidence for a "beauty-premium" that overrides any putative effect of kin.

RevDate: 2020-02-25

Poirotte C, MJE Charpentier (2020)

Unconditional care from close maternal kin in the face of parasites.

Biology letters, 16(2):20190869.

Several species mitigate relationships according to their conspecifics' parasite status. Yet, this defence strategy comes with the costs of depriving individuals from valuable social bonds. Animals therefore face a trade-off between the costs of pathogen exposure and the benefits of social relationships. According to the models of social evolution, social bonds are highly kin-biased. However, whether kinship mitigates social avoidance of contagious individuals has never been tested so far. Here, we build on previous research to demonstrate that mandrills (Mandrillus sphinx) modulate social avoidance of contagious individuals according to kinship: individuals do not avoid grooming their close maternal kin when contagious (parasitized with oro-faecally transmitted protozoa), although they do for more distant or non-kin. While individuals' parasite status has seldom been considered as a trait impacting social relationships in animals, this study goes a step beyond by showing that kinship balances the effect of health status on social behaviour in a non-human primate.

RevDate: 2020-02-17

Kappeler PM, L Pozzi (2019)

Evolutionary transitions toward pair living in nonhuman primates as stepping stones toward more complex societies.

Science advances, 5(12):eaay1276 pii:aay1276.

Nonhuman primate societies vary tremendously in size and composition, but how and why evolutionary transitions among different states occurred remains highly controversial. In particular, how many times pair living evolved and the social states of the ancestors of pair- and group-living species remains contentious. We examined evolutionary transitions in primate social evolution by using new, independent categorizations of sociality and different phylogenetic hypotheses with a vastly expanded dataset. Using Bayesian phylogenetic comparative methods, we consistently found the strongest support for a model that invokes frequent transitions between solitary ancestors and pair-living descendants, with the latter giving rise to group-living species. This result was robust to systematic variation in social classification, sample size, and phylogeny. Our analyses therefore indicate that pair living was a stepping stone in the evolution of structurally more complex primate societies, a result that bolsters the role of kin selection in social evolution.

RevDate: 2020-02-14

Patel M, West SA, JM Biernaskie (2020)

Kin discrimination, negative relatedness, and how to distinguish between selfishness and spite.

Evolution letters, 4(1):65-72 pii:EVL3150.

Spiteful behaviors occur when an actor harms its own fitness to inflict harm on the fitness of others. Several papers have predicted that spite can be favored in sufficiently small populations, even when the harming behavior is directed indiscriminately at others. However, it is not clear that truly spiteful behavior could be favored without the harm being directed at a subset of social partners with relatively low genetic similarity to the actor (kin discrimination, causing a negative relatedness between actor and harmed recipient). Using mathematical models, we show that (1) the evolution of spite requires kin discrimination; (2) previous models suggesting indiscriminate spite involve scenarios where the actor gains a direct feedback benefit from harming others, and so the harming is selfish rather than spiteful; (3) extreme selfishness can be favored in small populations (or, more generally, under local competition) because this is where the direct feedback benefit of harming is greatest.

RevDate: 2020-01-30
CmpDate: 2020-01-30

Butynski TM (1982)

Harem-male replacement and infanticide in the blue monkey (Cercopithecus mitus stuhlmanni) in the Kibale Forest, Uganda.

American journal of primatology, 3(1-4):1-22.

This paper (1) describes the first observations of male replacement and infanticide in the blue monkey (Cercopithecus mitis stuhlmanni), (2) examines these observations in light of those hypotheses put forth to explain infanticide, and (3) presents two basic models through which additional hypotheses are developed. Five groups of blue monkeys were observed for 2,724 hr in the Kibale Forest, Uganda. The pattern of infanticide in the blue monkey was strikingly similar to that reported for other species of primates living in one-male bisexual groups. Data concerning infanticide in the blue monkey do not support the hypothesis that infanticide is a maladaptive behavioral pathology. The data indirectly support the hypothesis that infanticide is part of a flexible, adaptive reproductive strategy of new harem-males. According to Model I, two of the hypothese for explaining how infanticide may be adaptive to the perpetrator are not mutually exclusive. Model II suggests that the rate of infanticide is directly related to competition among males for females and indirectly related to tenure length of harem-males. Models I and II underscore the importance of understanding what variables determine tenure length in haremmales. It is cocluded that length of male tenure is most likely a critical determinant of inclusive fitness not only for males but also for females.

RevDate: 2020-01-22

Montazeaud G, Rousset F, Fort F, et al (2020)

Farming plant cooperation in crops.

Proceedings. Biological sciences, 287(1919):20191290.

Selection of the fittest can promote individual competitiveness but often results in the erosion of group performance. Recently, several authors revisited this idea in crop production and proposed new practices based on selection for cooperative phenotypes, i.e. phenotypes that increase crop yield through decreased competitiveness. These recommendations, however, remain difficult to evaluate without a formal description of crop evolutionary dynamics under different selection strategies. Here, we develop a theoretical framework to investigate the evolution of cooperation-related traits in crops, using plant height as a case study. Our model is tailored to realistic agricultural practices and shows that combining high plant density, high relatedness and selection among groups favours the evolution of shorter plants that maximize grain yield. Our model allows us to revisit past and current breeding practices in light of kin selection theory, and yields practical recommendations to increase cooperation among crops and promote sustainable agriculture.

RevDate: 2020-01-27

Komatsu H, Kubota H, Tanaka N, et al (2020)

Designing information provision to serve as a reminder of altruistic benefits: A case study of the risks of air pollution caused by industrialization.

PloS one, 15(1):e0227024.

A well-known phenomenon is that humans perceive risks to threaten future generations as more dangerous in many cases. However, this tendency could be changed depending on certain conditions and could potentially be explained by the evolution of altruism. Our multi-agent simulation model, which was constructed to identify attributes contributing to subjective assessment of a risk source based on kin selection theory, showed that support from relatives can affect the agents' subjective risk assessment. We utilize this insight, which has never been explored in the context of nudge, to show that real-world messages reminding respondents that they are supported by their relatives can moderate the perception of a risk source as extremely dangerous. A randomized control trial based on an internet questionnaire survey was conducted to identify the intervention effect of such messages, using air pollution caused by industrialization as the risk source for the case study. Our analysis suggests that messages moderate extreme attitudes. Presentation of additional visual information can boost the sense of familial support and increase the effect of a message compared with a message comprising only textual information. The attributes and personality traits of the respondents who are responsive to the intervention message are also discussed.

RevDate: 2020-01-21

Brucks D, AMP von Bayern (2020)

Parrots Voluntarily Help Each Other to Obtain Food Rewards.

Current biology : CB, 30(2):292-297.e5.

Helping others to obtain benefits, even at a cost to oneself, poses an evolutionary puzzle [1]. While kin selection explains such "selfless" acts among relatives, only reciprocity (paying back received favors) entails fitness benefits for unrelated individuals [2]. So far, experimental evidence for both prosocial helping (providing voluntary assistance for achieving an action-based goal) and reciprocity has been reported in a few mammals but no avian species [3]. In order to gain insights into the evolutionary origins of these behaviors, the capacity of non-mammalian species for prosociality and for reciprocity needs to be investigated. We tested two parrot species in an instrumental-helping paradigm involving "token transfer." Here, actors could provide tokens to their neighbor, who could exchange them with an experimenter for food. To verify whether the parrots understood the task's contingencies, we systematically varied the presence of a partner and the possibility for exchange. We found that African grey parrots voluntarily and spontaneously transferred tokens to conspecific partners, whereas significantly fewer transfers occurred in the control conditions. Transfers were affected by the strength of the dyads' affiliation and partially by the receivers' attention-getting behaviors. Furthermore, the birds reciprocated the help once the roles were reversed. Blue-headed macaws, in contrast, transferred hardly any tokens. Species differences in social tolerance might explain this discrepancy. These findings show that instrumental helping based on a prosocial attitude, accompanied but potentially not sustained by reciprocity, is present in parrots, suggesting that this capacity evolved convergently in this avian group and mammals.

RevDate: 2020-01-03

Chaves ÓM, Martins V, Camaratta D, et al (2020)

Successful adoption of an orphan infant in a wild group of brown howler monkeys.

Primates; journal of primatology pii:10.1007/s10329-019-00785-2 [Epub ahead of print].

The rarity of infant adoption in wild primates compromises our understanding of its consequences for the participating individuals. We report the first case of successful infant adoption in a wild group of brown howler monkeys (Alouatta guariba clamitans). We evaluated the potential costs of the behavior for the adoptive mother by comparing her activity budget and diet before and after the adoption. On 18 June 2013, a domestic dog killed the mother of a 2-month-old male infant (Victorio) as she attempted to cross a canopy gap. Victorio was immediately rescued from her belly by a researcher and released in a climber near another infant-carrying female (Sofia, his likely grandmother). Sofia recovered him 2 min later. She carried and breastfed both infants during the next 4 weeks, when her own infant disappeared. We monitored Victorio until he reached adulthood in March 2018. Sofia fed more (mainly on immature leaves) when she nursed only Victorio than when nursing only her own or both infants. Assuming that the disappearance of Sofia's own infant was unrelated to the adoption of Victorio, we conclude that his successful adoption may contribute to Sofia's inclusive fitness if he sires his own infants.

RevDate: 2020-01-08

Martinig AR, McAdam AG, Dantzer B, et al (2019)

The new kid on the block: immigrant males win big whereas females pay fitness cost after dispersal.

Dispersal is nearly universal; yet, which sex tends to disperse more and their success thereafter depends on the fitness consequences of dispersal. We asked if lifetime fitness differed between residents and immigrants (successful between-population dispersers) and their offspring using 29 years of monitoring from North American red squirrels (Tamiasciurus hudsonicus) in Canada. Compared to residents, immigrant females had 23% lower lifetime breeding success (LBS), while immigrant males had 29% higher LBS. Male immigration and female residency were favoured. Offspring born to immigrants had 15-43% lower LBS than offspring born to residents. We conclude that immigration benefitted males, but not females, which appeared to be making the best of a bad lot. Our results are in line with male-biased dispersal being driven by local mate competition and local resource enhancement, while the intergenerational cost to immigration is a new complication in explaining the drivers of sex-biased dispersal.

RevDate: 2020-01-01

Nattrass S, Croft DP, Ellis S, et al (2019)

Postreproductive killer whale grandmothers improve the survival of their grandoffspring.

Proceedings of the National Academy of Sciences of the United States of America [Epub ahead of print].

Understanding why females of some mammalian species cease ovulation prior to the end of life is a long-standing interdisciplinary and evolutionary challenge. In humans and some species of toothed whales, females can live for decades after stopping reproduction. This unusual life history trait is thought to have evolved, in part, due to the inclusive fitness benefits that postreproductive females gain by helping kin. In humans, grandmothers gain inclusive fitness benefits by increasing their number of surviving grandoffspring, referred to as the grandmother effect. Among toothed whales, the grandmother effect has not been rigorously tested. Here, we test for the grandmother effect in killer whales, by quantifying grandoffspring survival with living or recently deceased reproductive and postreproductive grandmothers, and show that postreproductive grandmothers provide significant survival benefits to their grandoffspring above that provided by reproductive grandmothers. This provides evidence of the grandmother effect in a nonhuman menopausal species. By stopping reproduction, grandmothers avoid reproductive conflict with their daughters, and offer increased benefits to their grandoffspring. The benefits postreproductive grandmothers provide to their grandoffspring are shown to be most important in difficult times where the salmon abundance is low to moderate. The postreproductive grandmother effect we report, together with the known costs of late-life reproduction in killer whales, can help explain the long postreproductive life spans of resident killer whales.

RevDate: 2019-12-30

Thomas F, Giraudeau M, Renaud F, et al (2019)

Can postfertile life stages evolve as an anticancer mechanism?.

PLoS biology, 17(12):e3000565.

Why a postfertile stage has evolved in females of some species has puzzled evolutionary biologists for over 50 years. We propose that existing adaptive explanations have underestimated in their formulation an important parameter operating both at the specific and the individual levels: the balance between cancer risks and cancer defenses. During their life, most multicellular organisms naturally accumulate oncogenic processes in their body. In parallel, reproduction, notably the pregnancy process in mammals, exacerbates the progression of existing tumors in females. When, for various ecological or evolutionary reasons, anticancer defenses are too weak, given cancer risk, older females could not pursue their reproduction without triggering fatal metastatic cancers, nor even maintain a normal reproductive physiology if the latter also promotes the growth of existing oncogenic processes, e.g., hormone-dependent malignancies. At least until stronger anticancer defenses are selected for in these species, females could achieve higher inclusive fitness by ceasing their reproduction and/or going through menopause (assuming that these traits are easier to select than anticancer defenses), thereby limiting the risk of premature death due to metastatic cancers. Because relatively few species experience such an evolutionary mismatch between anticancer defenses and cancer risks, the evolution of prolonged life after reproduction could also be a rare, potentially transient, anticancer adaptation in the animal kingdom.

RevDate: 2020-01-15

Gow EA, Arcese P, Dagenais D, et al (2019)

Testing predictions of inclusive fitness theory in inbreeding relatives with biparental care.

Proceedings. Biological sciences, 286(1916):20191933.

Inclusive fitness theory predicts that parental care will vary with relatedness between potentially caring parents and offspring, potentially shaping mating system evolution. Systems with extra-pair paternity (EPP), and hence variable parent-brood relatedness, provide valuable opportunities to test this prediction. However, existing theoretical and empirical studies assume that a focal male is either an offspring's father with no inbreeding, or is completely unrelated. We highlight that this simple dichotomy does not hold given reproductive interactions among relatives, complicating the effect of EPP on parent-brood relatedness yet providing new opportunities to test inclusive fitness theory. Accordingly, we tested hierarchical hypotheses relating parental feeding rate to parent-brood relatedness, parent kinship and inbreeding, using song sparrows (Melospiza melodia) experiencing natural variation in relatedness. As predicted, male and female feeding rates increased with relatedness to a dependent brood, even controlling for brood size. Male feeding rate tended to decrease as paternity loss increased, and increased with increasing kinship and hence inbreeding between socially paired mates. We thereby demonstrate that variation in a key component of parental care concurs with subtle predictions from inclusive fitness theory. We additionally highlight that such effects can depend on the underlying social mating system, potentially generating status-specific costs of extra-pair reproduction.

RevDate: 2019-12-18

Fumagalli SE, SH Rice (2019)

Stochasticity and non-additivity expose hidden evolutionary pathways to cooperation.

PloS one, 14(12):e0225517.

Cooperation is widespread across the tree of life, with examples ranging from vertebrates to lichens to multispecies biofilms. The initial evolution of such cooperation is likely to involve interactions that produce non-additive fitness effects among small groups of individuals in local populations. However, most models for the evolution of cooperation have focused on genealogically related individuals, assume that the factors influencing individual fitness are deterministic, that populations are very large, and that the benefits of cooperation increase linearly with the number of cooperative interactions. Here we show that stochasticity and non-additive interactions can facilitate the evolution of cooperation in small local groups. We derive a generalized model for the evolution of cooperation and show that if cooperation reduces the variance in individual fitness (separate from its effect on average fitness), this can aid in the evolution of cooperation through directional stochastic effects. In addition, we show that the potential for the evolution of cooperation is influenced by non-additivity in benefits with cooperation being more likely to evolve when the marginal benefit of a cooperative act increases with the number of such acts. Our model compliments traditional cooperation models (kin selection, reciprocal cooperation, green beard effect, etc.) and applies to a broad range of cooperative interactions seen in nature.

RevDate: 2020-01-08

Clech L, Hazel A, MA Gibson (2019)

Does Kin-Selection Theory Help to Explain Support Networks among Farmers in South-Central Ethiopia?.

Human nature (Hawthorne, N.Y.), 30(4):422-447.

Social support networks play a key role in human livelihood security, especially in vulnerable communities. Here we explore how evolutionary ideas of kin selection and intrahousehold resource competition can explain individual variation in daily support network size and composition in a south-central Ethiopian agricultural community. We consider both domestic and agricultural help across two generations with different wealth-transfer norms that yield different contexts for sibling competition. For farmers who inherited land rights from family, firstborns were more likely to report daily support from parents and to have larger nonparental kin networks (n = 180). Compared with other farmers, firstborns were also more likely to reciprocate their parents' support, and to help nonparental kin without reciprocity. For farmers who received land rights from the government (n = 151), middle-born farmers reported more nonparental kin in their support networks compared with other farmers; nonreciprocal interactions were particularly common in both directions. This suggests a diversification of adult support networks to nonparental kin, possibly in response to a long-term parental investment disadvantage of being middle-born sons. In all instances, regardless of inheritance, lastborn farmers were the most disadvantaged in terms of kin support. Overall, we found that nonreciprocal interactions among farmers followed kin selection predictions. Direct reciprocity explained a substantial part of the support received from kin, suggesting the importance of the combined effects of kin selection and reciprocity for investment from kin.

RevDate: 2020-01-08

Boesch L, R Berger (2019)

Explaining Fairness : Results from an Experiment in Guinea.

Human nature (Hawthorne, N.Y.), 30(4):398-421.

Fairness is undoubtedly an essential normative concept in humans and promotes cooperation in human societies. The fact that fairness exists is puzzling, however, because it works against the short-term interest of individuals. Theories of genetic evolution, cultural evolution, and gene-culture coevolution identify plausible mechanisms for the evolution of fairness in humans. Such mechanisms include kin selection, the support of group-beneficial moral norms through ethnic markers, free partner choice with equal outside options, and free partner choice with reputation as well as spite in small populations. Here, we present the results of a common-pool resource game experiment on sharing. Based on data from 37 multiethnic villages in a subsistence agricultural population in Foutah Djallon, Guinea, we show that fair behavior in our experiment increased with increasing ethnic homogeneity and market integration. Group size and kinship had the opposite effect. Overall, fair behavior was not conditional on reputation. Instead, the ability of the different village populations to support individuals' fairness in situations lacking the opportunity to build a positive reputation varied significantly. Our results suggest that evolutionary theory provides a useful framework for the analysis of fairness in humans.

RevDate: 2019-12-31

Winnicki SK, Munguía SM, Williams EJ, et al (2019)

Social interactions do not drive territory aggregation in a grassland songbird.

Ecology [Epub ahead of print].

Understanding the drivers of animal distributions is a fundamental goal of ecology and informs habitat management. The costs and benefits of colonial aggregations in animals are well established, but the factors leading to aggregation in territorial animals remain unclear. Territorial animals might aggregate to facilitate social behavior such as (1) group defense from predators and/or parasites, (2) cooperative care of offspring, (3) extra-pair mating, and/or (4) mitigating costs of extra-pair mating through kin selection. Using experimental and observational methods, we tested predictions of all four hypotheses in a tallgrass prairie in northeast Kansas, United States. Grasshopper Sparrow (Ammodramus savannarum) males formed clumps of territories in some parts of the site while leaving other apparently suitable areas unoccupied. Despite substantial sampling effort (653 territories and 223 nests), we found no support for any hypothesized social driver of aggregation, nor evidence that aggregation increases nest success. Our results run counter to previous evidence that conspecific interactions shape territory distributions. These results suggest one of the following alternatives: (1) the benefits of aggregation accrue to different life-history stages, or (2) the benefits of territory aggregation may be too small to detect in short-term studies and/or the consequences of aggregation are sufficiently temporally and spatially variable that they do not always appear to be locally adaptive, perhaps exacerbated by changing landscape contexts and declining population sizes.

RevDate: 2019-11-06

Paternotte C (2019)

Social evolution and the individual-as-maximising-agent analogy.

Studies in history and philosophy of biological and biomedical sciences pii:S1369-8486(19)30113-X [Epub ahead of print].

Does natural selection tend to maximise something? Does it produce individuals who act as if they maximised something? These questions have long occupied evolutionary theorists, and have proven especially tricky in the case of social evolution, which is known for leading to apparently suboptimal states. This paper investigates recent results about maximising analogies - especially regarding whether individuals should be considered as if they maximised their inclusive fitness - and compares the fruitfulness of global and local approaches. I assess Okasha & Martens's recent local approach to the individual-as-maximising-agent analogy and its robustness with respect to interactive situations. I then defend the relative merits of a comparable global approach, arguing that it is conceptually on a par and heuristically advantageous.

RevDate: 2020-01-08

Keaney TA, Wong HWS, Dowling DK, et al (2019)

Mother's curse and indirect genetic effects: Do males matter to mitochondrial genome evolution?.

Journal of evolutionary biology [Epub ahead of print].

Maternal inheritance of mitochondrial DNA (mtDNA) was originally thought to prevent any response to selection on male phenotypic variation attributable to mtDNA, resulting in a male-biased mtDNA mutation load ("mother's curse"). However, the theory underpinning this claim implicitly assumes that a male's mtDNA has no effect on the fitness of females he comes into contact with. If such "mitochondrially encoded indirect genetics effects" (mtIGEs) do in fact exist, and there is relatedness between the mitochondrial genomes of interacting males and females, male mtDNA-encoded traits can undergo adaptation after all. We tested this possibility using strains of Drosophila melanogaster that differ in their mtDNA. Our experiments indicate that female fitness is influenced by the mtDNA carried by males that the females encounter, which could plausibly allow the mitochondrial genome to evolve via kin selection. We argue that mtIGEs are probably common, and that this might ameliorate or exacerbate mother's curse.

RevDate: 2019-10-24

Levin SR, Caro SM, Griffin AS, et al (2019)

Honest signaling and the double counting of inclusive fitness.

Evolution letters, 3(5):428-433.

Inclusive fitness requires a careful accounting of all the fitness effects of a particular behavior. Verbal arguments can potentially exaggerate the inclusive fitness consequences of a behavior by including the fitness of relatives that was not caused by that behavior, leading to error. We show how this "double-counting" error can arise, with a recent example from the signaling literature. In particular, we examine the recent debate over whether parental divorce increases parent-offspring conflict, selecting for less honest signaling. We found that, when all the inclusive fitness consequences are accounted for, parental divorce increases conflict between siblings, in a way that they can select for less honest signaling. This prediction is consistent with the empirical data. More generally, our results illustrate how verbal arguments can be misleading, emphasizing the advantage of formal mathematical models.

RevDate: 2019-11-25

Swedell L, T Plummer (2019)

Social evolution in Plio-Pleistocene hominins: Insights from hamadryas baboons and paleoecology.

Journal of human evolution, 137:102667.

Reconstructions of hominin evolution have long benefited from comparisons with nonhuman primates, especially baboons and chimpanzees. The hamadryas baboon (Papio hamadryas) is arguably one of the best such models, as it exhibits both the male kin bonding and the cross-sex pair bonding thought to have been important in hominin evolution. Here we link processes of behavioral evolution in hamadryas baboons with those in a Plio-Pleistocene hominin, provisionally identified as Homo erectus (sensu lato) - a pivotal species in that its larger body and brain size and wider ranging patterns increased female costs of reproduction, increasing the importance of sociality. The combination of these higher costs of reproduction and shifts in diet and food acquisition have previously been argued to have been alleviated either via strengthening of male-female bonds (involving male provisioning and the evolution of monogamy) or via the assistance of older, post-reproductive females (leading to post-reproductive longevity in females, i.e., the grandmother hypothesis). We suggest that both arrangements could have been present in Plio-Pleistocene hominins if they lived in multilevel societies. Here we expand on our earlier scenario with two sets of recent data in support of it, (1) archaeological data from the 2 million year old Oldowan site of Kanjera South, Kenya and other sites that are suggestive of tool dependent foraging on nutrient dense resources (animal carcasses and plant underground storage organs), cooperation, and food sharing; and (2) a pattern of genetic variation in hamadryas baboons that suggests the operation of kin selection among both males and females at multiple levels of society. Taken together, these two sets of data strengthen our model and support the idea of a complex society linked by male-male, male-female, and female-female bonds at multiple levels of social organization in Plio-Pleistocene hominins.

RevDate: 2019-10-23

Nonacs P (2019)

Reproductive skew in cooperative breeding: Environmental variability, antagonistic selection, choice, and control.

Ecology and evolution, 9(18):10163-10175.

A multitude of factors may determine reproductive skew among cooperative breeders. One explanation, derived from inclusive fitness theory, is that groups can partition reproduction such that subordinates do at least as well as noncooperative solitary individuals. The majority of recent data, however, fails to support this prediction; possibly because inclusive fitness models cannot easily incorporate multiple factors simultaneously to predict skew. Notable omissions are antagonistic selection (across generations, genes will be in both dominant and subordinate bodies), constraints on the number of sites suitable for successful reproduction, choice in which group an individual might join, and within-group control or suppression of competition. All of these factors and more are explored through agent-based evolutionary simulations. The results suggest the primary drivers for the initial evolution of cooperative breeding may be a combination of limited suitable sites, choice across those sites, and parental manipulation of offspring into helping roles. Antagonistic selection may be important when subordinates are more frequent than dominants. Kinship matters, but its main effect may be in offspring being available for manipulation while unrelated individuals are not. The greater flexibility of evolutionary simulations allows the incorporation of species-specific life histories and ecological constraints to better predict sociobiology.

RevDate: 2019-10-23

Deng K, Liu W, DH Wang (2019)

Relatedness and spatial distance modulate intergroup interactions: experimental evidence from a social rodent.

Current zoology, 65(5):527-534.

Kin selection theory predicts that individuals should generally behave less aggressively or more amicably towards relatives than nonkin. However, how individuals treat conspecifics depends on genetic relatedness but also on the ecological context, which influences the benefits and costs of their interactions. In this study, we used microsatellite DNA markers and behavioral tests to examine the influence of kinship and proximity on the social behavior of Mongolian gerbils Meriones unguiculatus living in different social groups, and whether these effects varied with sex and season. We recorded the duration of 4 behavioral categories (investigative, neutral, amicable, and agonistic) during a 10-min pairwise test. We found that genetic relatedness had significant effects on the duration of investigative, neutral, and amicable behavior, but not on agonistic behavior. We also found significant interaction effects of relatedness and distance between burrow systems (i.e., spatial distance) on investigative, neutral, and amicable behavior, which suggests that the effects of kinship on social behavior were restricted by spatial proximity. The interaction effect between sex and relatedness on amicable behavior showed that male gerbils became more intimate with individuals of the same sex that had higher pairwise relatedness than females. Furthermore, both male and female gerbils enhanced their aggression during the food-hoarding season, but the intensity of these changes was significantly higher in females. Overall, our results suggest that the effects of kinship and spatial proximity on social behavior exhibit sexual or seasonal patterns, thereby implying ecological context-dependent responses to out-group individuals in Mongolian gerbils.

RevDate: 2019-10-23

Freeman AR, Wood TJ, Bairos-Novak KR, et al (2019)

Gone girl: Richardson's ground squirrel offspring and neighbours are resilient to female removal.

Royal Society open science, 6(9):190904.

Within matrilineal societies, the presence of mothers and female kin can greatly enhance survival and reproductive success owing to kin-biased alarm calling, cooperation in territory defence, protection from infanticidal conspecifics, joint care of young and enhanced access to resources. The removal of mothers by predators or disease is expected to increase the stress experienced by offspring via activation of their hypothalamic-pituitary-adrenal axis, increasing circulating glucocorticoids and reducing offspring survival and reproductive success. Yet, few studies have removed mothers in the post-weaning period to examine the assumed physiological and fitness consequences associated with these mortality events. We examined how the loss of a mother affects juvenile Richardson's ground squirrels' (Urocitellus richardsonii) faecal glucocorticoid metabolites and their survival. Given that neighbours are often close kin, we further hypothesized that conspecific removal would similarly diminish the fitness of neighbouring individuals. Upon removing the mother, we detected no impact on offspring or neighbouring conspecific faecal glucocorticoid metabolites in the removal year, or on overwinter survival in the following year. Furthermore, no impact on neighbour reproductive success was detected. Given the high predation rates of ground squirrels in wild populations, resilience to a changing social environment would prove adaptive for both surviving kin and non-kin.

RevDate: 2020-01-19

Hervey SD, Barnas AF, Stechmann TJ, et al (2019)

Kin grouping is insufficient to explain the inclusive fitness gains of conspecific brood parasitism in the common eider.

Molecular ecology, 28(21):4825-4838.

Conspecific brood parasitism allows females to exploit other females' nests and enhance their reproductive output. Here, we test a recent theoretical model of how host females gain inclusive fitness from brood parasitism. High levels of relatedness between host and parasitizer can be maintained either by: (a) kin recognizing and parasitizing each other as a form of cooperative breeding or (b) natal philopatry and nest site fidelity facilitating the formation of kin groups, thereby increasing the probability of parasitism between relatives nesting in close proximity. To address these two hypotheses we genotyped feathers and hatch membranes of common eiders (Somateria mollissima) from western Hudson Bay, Canada, using a noninvasive sampling methodology. We found that most instances of brood parasitism do result in inclusive fitness gains. Furthermore, females with failed nests moved an average of 492 m from their previous year's nest site, while successful females only moved an average of 13 m. Therefore, we observed host-parasite relatedness can occur at levels higher than would be expected by chance even in the absence of kin grouping, suggesting that closely related females nesting near one another is not essential to maintain high host-parasitizer relatedness. In addition, kin grouping is only a transient phenomenon that cannot occur every year due to the propensity for females of failed nests to nest farther away from their nest site in subsequent years than females with successful nests, which provides support for kin recognition as a more likely mechanism to maintain high host-parasitizer relatedness over time.

RevDate: 2019-09-26

Fréville H, Roumet P, Rode NO, et al (2019)

Preferential helping to relatives: A potential mechanism responsible for lower yield of crop variety mixtures?.

Evolutionary applications, 12(9):1837-1849 pii:EVA12842.

Variety mixtures, the cultivation of different genotypes within a field, have been proposed as a way to increase within-crop diversity, allowing the development of more sustainable agricultural systems with reduced environmental costs. Although mixtures have often been shown to over-yield the average of component varieties in pure stands, decreased yields in mixtures have also been documented. Kin selection may explain such pattern, whenever plants direct helping behaviors preferentially toward relatives and thus experience stronger competition when grown with less related neighbors, lowering seed production of mixtures. Using varieties of durum wheat originating from traditional Moroccan agrosystems, we designed a greenhouse experiment to address whether plants reduced competition for light by limiting stem elongation when growing with kin and whether such phenotypic response resulted in higher yield of kin groups. Seeds were sown in groups of siblings and nonkin, each group containing a focal plant surrounded by four neighbors. At the group level, mean plant height and yield did not depend upon relatedness among competing plants. At the individual level, plant height was not affected by genetic relatedness to neighbors, after accounting for direct genetic effects that might induce among-genotype differences in the ability to capture resources that do not depend on relatedness. Moreover, in contrast to our predictions, shorter plants had lower inclusive fitness. Phenotypic plasticity in height was very limited in response to neighbor genotypes. This suggests that human selection in crops may have attenuated shade-avoidance responses to competition for light. Future research on preferential helping to relatives in crops might thus target social traits that drive competition for other resources than light. Overall, our study illustrates the relevance of tackling agricultural issues from an evolutionary standpoint and calls for extending such approaches to a larger set of crop species.

RevDate: 2019-09-19

Tanskanen AO, Danielsbacka M, Coall DA, et al (2019)

Transition to Grandparenthood and Subjective Well-Being in Older Europeans: A Within-Person Investigation Using Longitudinal Data.

Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior, 17(3):1474704919875948.

The transition to grandparenthood, that is the birth of the first grandchild, is often assumed to increase the subjective well-being of older adults; however, prior studies are scarce and have provided mixed results. Investigation of the associations between grandparenthood and subjective well-being, measured by self-rated life satisfaction, quality of life scores, and depressive symptoms, used the longitudinal Survey of Health, Ageing and Retirement in Europe from 13 countries, including follow-up waves between 2006 and 2015 (n = 64,940 person-observations from 38,456 unique persons of whom 18,207 had two or more measurement times). Both between-person and within-person (or fixed-effect) regression models were executed, where between-person associations represent results across individuals, that is, between grandparents and non-grandparents; within-person associations represent an individual's variation over time, that is, they consider whether the transition to grandparenthood increases or decreases subjective well-being. According to the between-person models, both grandmothers and grandfathers reported higher rate of life satisfaction and quality of life than non-grandparents. Moreover, grandmothers reported fewer depressive symptoms than women without grandchildren. The within-person models indicated that entry into grandmotherhood was associated with both improved quality of life scores and improved life satisfaction. These findings are discussed with reference to inclusive fitness theory, parental investment theory, and the grandmother hypothesis.

RevDate: 2019-09-24

Kalske A, Shiojiri K, Uesugi A, et al (2019)

Insect Herbivory Selects for Volatile-Mediated Plant-Plant Communication.

Current biology : CB, 29(18):3128-3133.e3.

Plant volatile organic compounds (VOCs) are major vehicles of information transfer between organisms and mediate many ecological interactions [1-3]. Altering VOC emission in response to herbivore damage has been hypothesized to be adaptive, as it can deter subsequent herbivores [4], attract natural enemies of herbivores [5], or transmit information about attacks between distant parts of the same plant [6-9]. Neighboring plants may also respond to these VOC cues by priming their own defenses against oncoming herbivory, thereby reducing future damage [10-12]. However, under which conditions such information sharing provides fitness benefits to emitter plants, and, therefore, whether selection by herbivores affects the evolution of such VOC signaling, is still unclear [13]. Here, we test the predictions of two alternative hypotheses, the kin selection and mutual benefits hypotheses [14], to uncover the selective environment that may favor information sharing in plants. Measuring the response to natural selection in Solidago altissima, we found strong effects of herbivory on the way plants communicated with neighbors. Plants from populations that experienced selection by insect herbivory induced resistance in all neighboring conspecifics by airborne cues, whereas those from populations experiencing herbivore exclusion induced resistance only in neighbors of the same genotype. Furthermore, the information-sharing plants converged on a common, airborne VOC signal upon damage. We demonstrate that herbivory can drive the evolution of plant-plant communication via induction of airborne cues and suggest plants as a model system for understanding information sharing and communication among organisms in general.

RevDate: 2020-01-27

Berg EC, Lind MI, Monahan S, et al (2019)

Kin but less than kind: within-group male relatedness does not increase female fitness in seed beetles.

Proceedings. Biological sciences, 286(1910):20191664.

Theory maintains within-group male relatedness can mediate sexual conflict by reducing male-male competition and collateral harm to females. We tested whether male relatedness can lessen female harm in the seed beetle Callosobruchus maculatus. Male relatedness did not influence female lifetime reproductive success or individual fitness across two different ecologically relevant scenarios of mating competition. However, male relatedness marginally improved female survival. Because male relatedness improved female survival in late life when C. maculatus females are no longer producing offspring, our results do not provide support for the role of within-group male relatedness in mediating sexual conflict. The fact that male relatedness improves the post-reproductive part of the female life cycle strongly suggests that the effect is non-adaptive. We discuss adaptive and non-adaptive mechanisms that could result in reduced female harm in this and previous studies, and suggest that cognitive error is a likely explanation.

RevDate: 2019-09-06

Smith AL, Atwater DZ, RM Callaway (2019)

Early Sibling Conflict May Ultimately Benefit the Family.

The American naturalist, 194(4):482-487.

Relatives often interact differently with each other than with nonrelatives, and whether kin cooperate or compete has important consequences for the evolution of mating systems, seed size, dispersal, and competition. Previous research found that the larger of the size dimorphic seeds produced by the annual plant Aegilops triuncialis suppressed germination of their smaller sibs by 25%-60%. Here, we found evidence for kin recognition and sibling rivalry later in life among Aegilops seedlings that places seed-seed interactions in a broader context. In experiments with size dimorphic seeds, seedlings reduced the growth of sibling seedlings by ∼40% but that of nonsibling seedlings by ∼25%. These sequential antagonistic interactions between seeds and then seedlings provide insight into conflict and cooperation among kin. Kin-based conflict among seeds may maintain dormancy for some seeds until the coast is clear of more competitive siblings. If so, biotically induced seed dormancy may be a unique form of cooperation, which increases the inclusive fitness of maternal plants and offspring by minimizing competition among kin.

RevDate: 2019-12-17
CmpDate: 2019-12-17

Madgwick PG, Belcher LJ, JB Wolf (2019)

Greenbeard Genes: Theory and Reality.

Trends in ecology & evolution, 34(12):1092-1103.

Greenbeard genes were proposed as a cartoonish thought experiment to explain why altruism can be a selfish strategy from the perspective of genes. The likelihood of finding a real greenbeard gene in nature was thought to be remote because they were believed to require a set of improbable properties. Yet, despite this expectation, there is an ongoing explosion in claimed discoveries of greenbeard genes. Bringing together the latest theory and experimental findings, we argue that there is a need to dispose of the cartoon presentation of a greenbeard to refocus their burgeoning empirical study on the more fundamental concept that the thought experiment was designed to illustrate.

RevDate: 2019-12-17
CmpDate: 2019-12-10

Martens J (2019)

Hamilton meets causal decision theory.

Studies in history and philosophy of biological and biomedical sciences, 77:101187.

In this paper, I contrast two mathematically equivalent ways of modeling the evolution of altruism, namely the classical inclusive fitness approach and a more recent, "direct fitness" approach. Though both are usually considered by evolutionists as mere different ways of representing the same causal process (i.e. that of kin selection), I argue that this consensus is misleading, for there is a fundamental ambiguity concerning the causal interpretation of the DF approach. Drawing on an analogy between the structure of inclusive fitness theory and that of causal decision theory (Stalnaker, 1972), I show that only the inclusive fitness framework can provide us with a proper, and unambiguous causal partition of the relevant variables involved in the evolution of altruism.

RevDate: 2019-09-01

Vostinar AE, Goldsby HJ, C Ofria (2019)

Suicidal selection: Programmed cell death can evolve in unicellular organisms due solely to kin selection.

Ecology and evolution, 9(16):9129-9136 pii:ECE35460.

Abstract: Unicellular organisms can engage in a process by which a cell purposefully destroys itself, termed programmed cell death (PCD). While it is clear that the death of specific cells within a multicellular organism could increase inclusive fitness (e.g., during development), the origin of PCD in unicellular organisms is less obvious. Kin selection has been shown to help maintain instances of PCD in existing populations of unicellular organisms; however, competing hypotheses exist about whether additional factors are necessary to explain its origin. Those factors could include an environmental shift that causes latent PCD to be expressed, PCD hitchhiking on a large beneficial mutation, and PCD being simply a common pathology. Here, we present results using an artificial life model to demonstrate that kin selection can, in fact, be sufficient to give rise to PCD in unicellular organisms. Furthermore, when benefits to kin are direct-that is, resources provided to nearby kin-PCD is more beneficial than when benefits are indirect-that is, nonkin are injured, thus increasing the relative amount of resources for kin. Finally, when considering how strict organisms are in determining kin or nonkin (in terms of mutations), direct benefits are viable in a narrower range than indirect benefits.

Open Research Badges: This article has been awarded Open Data and Open Materials Badges. All materials and data are publicly accessible via the Open Science Framework at

RevDate: 2020-01-08

Khodaei L, TAF Long (2019)

Kin recognition and co-operative foraging in Drosophila melanogaster larvae.

Journal of evolutionary biology, 32(12):1352-1361.

A long-standing goal for biologists and social scientists is to understand the factors that lead to the evolution and maintenance of co-operative behaviour between conspecifics. To that end, the fruit fly, Drosophila melanogaster, is becoming an increasingly popular model species to study sociality; however, most of the research to date has focused on adult behaviours. In this study, we set out to examine group-feeding behaviour by larvae and to determine whether the degree of relatedness between individuals mediates the expression co-operation. In a series of assays, we manipulated the average degree of relatedness in groups of third-instar larvae that were faced with resource scarcity, and measured the size, frequency and composition of feeding clusters, as well as the fitness benefits associated with co-operation. Our results suggest that larval D. melanogaster are capable of kin recognition (something that has not been previously described in this species), as clusters were more numerous, larger and involved more larvae, when more closely related kin were present in the social environment. These findings are discussed in the context of the correlated fitness-associated benefits of co-operation, the potential mechanisms by which individuals may recognize kin, and how that kinship may play an important role in facilitating the manifestation of this co-operative behaviour.

RevDate: 2019-09-23
CmpDate: 2019-09-23

Cayuela H, Boualit L, Laporte M, et al (2019)

Kin-dependent dispersal influences relatedness and genetic structuring in a lek system.

Oecologia, 191(1):97-112.

Kin selection and dispersal play a critical role in the evolution of cooperative breeding systems. Limited dispersal increases relatedness in spatially structured populations (population viscosity), with the result that neighbours tend to be genealogical relatives. Yet the increase in neighbours' fitness-related performance through altruistic interaction may also result in habitat saturation and thus exacerbate local competition between kin. Our goal was to detect the footprint of kin selection and competition by examining the spatial structure of relatedness and by comparing non-effective and effective dispersal in a population of a lekking bird, Tetrao urogallus. For this purpose, we analysed capture-recapture and genetic data collected over a 6-year period on a spatially structured population of T. urogallus in France. Our findings revealed a strong spatial structure of relatedness in males. They also indicated that the population viscosity could allow male cooperation through two non-exclusive mechanisms. First, at their first lek attendance, males aggregate in a lek composed of relatives. Second, the distance corresponding to non-effective dispersal dramatically outweighed effective dispersal distance, which suggests that dispersers incur high post-settlement costs. These two mechanisms result in strong population genetic structuring in males. In females, our findings revealed a lower level of spatial structure of relatedness and genetic structure in respect to males. Additionally, non-effective dispersal and effective dispersal distances in females were highly similar, which suggests limited post-settlement costs. These results indicate that kin-dependent dispersal decisions and costs have a genetic footprint in wild populations and are factors that may be involved in the evolution of cooperative courtship.

RevDate: 2019-11-19

Page AE, Thomas MG, Smith D, et al (2019)

Testing adaptive hypotheses of alloparenting in Agta foragers.

Nature human behaviour, 3(11):1154-1163.

Human children are frequently cared for by non-parental caregivers (alloparents), yet few studies have conducted systematic alternative hypothesis tests of why alloparents help. Here we explore whether predictions from kin selection, reciprocity, learning-to-mother and costly signalling hypotheses explain non-parental childcare among Agta hunter-gatherers from the Philippines. To test these hypotheses, we used high-resolution proximity data from 1,701 child-alloparent dyads. Our results indicated that reciprocity and relatedness were positively associated with the number of interactions with a child (our proxy for childcare). Need appeared more influential in close kin, suggesting indirect benefits, while reciprocity proved to be a stronger influence in non-kin, pointing to direct benefits. However, despite shared genes, close and distant kin interactions were also contingent on reciprocity. Compared with other apes, humans are unique in rapidly producing energetically demanding offspring. Our results suggest that the support that mothers require is met through support based on kinship and reciprocity.

RevDate: 2019-08-08

Schriver J, Perunovic WQE, Brymer K, et al (2019)

Do Relatives With Greater Reproductive Potential Get Help First?: A Test of the Inclusive Fitness Explanation of Kin Altruism.

Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior, 17(3):1474704919867094.

According to inclusive fitness theory, people are more willing to help those they are genetically related to because relatives share a kin altruism gene and are able to pass it along. We tested this theory by examining the effect of reproductive potential on altruism. Participants read hypothetical scenarios and chose between cousins (Studies 1 and 2) and cousins and friends (Study 3) to help with mundane chores or a life-or-death rescue. In life-or-death situations, participants were more willing to help a cousin preparing to conceive rather than adopt a child (Study 1) and a cousin with high rather than low chance of reproducing (Studies 2 and 3). Patterns in the mundane condition were less consistent. Emotional closeness also contributed to helping intentions (Studies 1 and 2). By experimentally manipulating reproductive potential while controlling for genetic relatedness and emotional closeness, we provide a demonstration of the direct causal effects of reproductive potential on helping intentions, supporting the inclusive fitness explanation of kin altruism.

RevDate: 2019-08-16

Berkowic D, S Markman (2019)

Weighing density and kinship: Aggressive behavior and time allocation in fire salamander (Salamandra infraimmaculata).

PloS one, 14(8):e0220499 pii:PONE-D-18-24785.

Kin-biased behavior (that is responding differentially to kin and non-kin) is thought to be adaptive in many social interactions. One example of this kin bias is behaving less aggressively toward a relative than a non-relative, a behavior which yields inclusive fitness benefits. However, data are lacking about the ability of animals to weigh their preference for kinship and the density of conspecifics simultaneously and to respond accordingly. Fire salamanders (Salamandra infraimmaculata) larviposit in high densities in ponds. Thus, larvae of different females confront competition and predation by other larvae. We studied whether larvae prefer their kin over particular density or vice versa. We experimentally used a transparent glass aquarium with inner chambers to test the responses of a focal larva toward its siblings and non-siblings. Specifically, we quantified the time a focal larva spent near its siblings or non-siblings, presented in varying densities, and the aggression level it demonstrated. We found that focal larvae spent more time near non-siblings if non-sibling and sibling groups were of equal density. The focal larvae were also more aggressive toward non-siblings. The results may be explained by the cannibalistic nature of these larvae: high density may provide more opportunities for food, especially when non-siblings are present. Further explanations for these findings may include other advantages of staying in a larger group and/or the stronger olfactory and visual stimulation offered by groups compared to a single individual. These findings suggest that larvae make differential responses toward conspecifics depending simultaneously on the level of relatedness and the density of the group. Such responses have important implications for social-aggregation decisions and may especially affect the fitness of cannibalistic species.

RevDate: 2019-07-30

Spivak M, Goblirsch M, M Simone-Finstrom (2019)

Social-medication in bees: the line between individual and social regulation.

Current opinion in insect science, 33:49-55.

We use the term social-medication to describe the deliberate consumption or use of plant compounds by social insects that are detrimental to a pathogen or parasite at the colony level, result in increased inclusive fitness to the colony, and have potential costs either at the individual or colony level in the absence of parasite infection. These criteria for social-medication differ from those for self-medication in that inclusive fitness costs and benefits are distinguished from individual costs and benefits. The consumption of pollen and nectar may be considered a form of social immunity if they help fight infection, resulting in a demonstrated increase in colony health and survival. However, the dietary use of pollen and nectar per se is likely not a form of social-medication unless there is a detriment or cost to their consumption in the absence of parasite infection, such as when they contain phytochemicals that are toxic at certain doses. We provide examples among social bees (bumblebees, stingless bees and honey bees) in which the consumption or use of plant compounds have a demonstrated role in parasite defense and health of the colony. We indicate where more work is needed to distinguish between prophylactic and therapeutic effects of these compounds, and whether the effects are observed at the individual or colony level.

RevDate: 2019-11-20
CmpDate: 2019-11-20

Birch J (2019)

Inclusive fitness as a criterion for improvement.

Studies in history and philosophy of biological and biomedical sciences, 76:101186.

I distinguish two roles for a fitness concept in the context of explaining cumulative adaptive evolution: fitness as a predictor of gene frequency change, and fitness as a criterion for phenotypic improvement. Critics of inclusive fitness argue, correctly, that it is not an ideal fitness concept for the purpose of predicting gene-frequency change, since it relies on assumptions about the causal structure of social interaction that are unlikely to be exactly true in real populations, and that hold as approximations only given a specific type of weak selection. However, Hamilton took this type of weak selection, on independent grounds, to be responsible for cumulative assembly of complex adaptations. In this special context, I argue that inclusive fitness is distinctively valuable as a criterion for improvement and a standard for optimality. Yet to call inclusive fitness a criterion for improvement and a standard for optimality is not to make any claim about the frequency with which inclusive fitness optimization actually occurs in nature. This is an empirical question that cannot be settled by theory alone. I close with some reflections on the place of inclusive fitness in the long running clash between 'causalist' and 'statisticalist' conceptions of fitness.

RevDate: 2019-11-20
CmpDate: 2019-11-20

Huneman P (2019)

Revisiting darwinian teleology: A case for inclusive fitness as design explanation.

Studies in history and philosophy of biological and biomedical sciences, 76:101188.

This paper elaborates a general framework to make sense of teleological explanations in Darwinian evolutionary biology. It relies on an attempt to tie natural selection to a sense of optimization. First, after assessing the objections made by any attempt to view selection as a maximising process within population genetics, it understands Grafen's Formal Darwinism (FD) as a conceptual link established between population genetics and behavioral ecology's adaptationist framework (without any empirical commitments). Thus I suggest that this provides a way to make sense of teleological explanations in biology under their various modes. Then the paper criticizes two major ways of accounting for teleology: a Darwinian one, the etiological view of biological functions, and a non-Darwinian one, here labeled "intrinsic teleology" view, which covers several subtypes of accounts, including plasticity-oriented conceptions of evolution or organizational views of function. The former is centered on traits while the latter is centered on organisms; this is shown to imply that both accounts are unable to provide a systematic understanding of biological teleology. Finally the paper argues that viewing teleology as maximization of inclusive fitness along the FD lines as understood here allows one to make sense of both the design of organisms and the individual traits as adaptions. Such notion is thereby claimed to be the proper meaning of teleology in evolutionary biology, since it avoids the opposed pitfalls of etiological views and intrinsic-teleology view, while accounting for the same features as they do.

RevDate: 2020-01-08

Mullon C, L Lehmann (2019)

An evolutionary quantitative genetics model for phenotypic (co)variances under limited dispersal, with an application to socially synergistic traits.

Evolution; international journal of organic evolution, 73(9):1695-1728.

Darwinian evolution consists of the gradual transformation of heritable traits due to natural selection and the input of random variation by mutation. Here, we use a quantitative genetics approach to investigate the coevolution of multiple quantitative traits under selection, mutation, and limited dispersal. We track the dynamics of trait means and of variance-covariances between traits that experience frequency-dependent selection. Assuming a multivariate-normal trait distribution, we recover classical dynamics of quantitative genetics, as well as stability and evolutionary branching conditions of invasion analyses, except that due to limited dispersal, selection depends on indirect fitness effects and relatedness. In particular, correlational selection that associates different traits within-individuals depends on the fitness effects of such associations between-individuals. We find that these kin selection effects can be as relevant as pleiotropy for the evolution of correlation between traits. We illustrate this with an example of the coevolution of two social traits whose association within-individuals is costly but synergistically beneficial between-individuals. As dispersal becomes limited and relatedness increases, associations between-traits between-individuals become increasingly targeted by correlational selection. Consequently, the trait distribution goes from being bimodal with a negative correlation under panmixia to unimodal with a positive correlation under limited dispersal.

RevDate: 2019-09-27
CmpDate: 2019-09-27

Garay J, Garay BM, Varga Z, et al (2019)

To save or not to save your family member's life? Evolutionary stability of self-sacrificing life history strategy in monogamous sexual populations.

BMC evolutionary biology, 19(1):147 pii:10.1186/s12862-019-1478-0.

BACKGROUND: For the understanding of human nature, the evolutionary roots of human moral behaviour are a key precondition. Our question is as follows: Can the altruistic moral rule "Risk your life to save your family members, if you want them to save your life" be evolutionary stable? There are three research approaches to investigate this problem: kin selection, group selection and population genetics modelling. The present study is strictly based on the last approach.

RESULTS: We consider monogamous and exogamous families, where at an autosomal locus, dominant-recessive alleles determine the phenotypes in a sexual population. Since all individuals' survival rate is determined by their altruistic family members, we introduce a new population genetics model based on the mating table approach and adapt the verbal definition of evolutionary stability to genotypes. In general, when the resident is recessive, a homozygote is an evolutionarily stable genotype (ESG), if the number of survivors of the resident genotype of the resident homozygote family is greater than that of non-resident heterozygote survivors of the family of the resident homozygote and mutant heterozygote genotypes. Using the introduced genotype dynamics we proved that in the recessive case ESG implies local stability of the altruistic genotype. We apply our general ESG conditions for self-sacrificing life history strategy when the number of new-born offspring does not depend on interactions within the family and the interactions are additive. We find that in this case our ESG conditions give back Hamilton's rule for evolutionary stability of the self-sacrificing life history strategy.

CONCLUSIONS: In spite of the fact that the kidney transplantations was not a selection factor during the earlier human evolution, nowadays "self-sacrificing" can be observed in the live donor kidney transplantations, when the donor is one of the family members. It seems that selection for self-sacrificing in family produced an innate moral tendency in modulating social cognition in human brain.

RevDate: 2019-07-19

Woodford P (2019)

Evaluating inclusive fitness.

Royal Society open science, 6(6):190644 pii:rsos190644.

RevDate: 2020-01-13

Koster J, Lukas D, Nolin D, et al (2019)

Kinship ties across the lifespan in human communities.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1780):20180069.

A hypothesis for the evolution of long post-reproductive lifespans in the human lineage involves asymmetries in relatedness between young immigrant females and the older females in their new groups. In these circumstances, inter-generational reproductive conflicts between younger and older females are predicted to resolve in favour of the younger females, who realize fewer inclusive fitness benefits from ceding reproduction to others. This conceptual model anticipates that immigrants to a community initially have few kin ties to others in the group, gradually showing greater relatedness to group members as they have descendants who remain with them in the group. We examine this prediction in a cross-cultural sample of communities, which vary in their sex-biased dispersal patterns and other aspects of social organization. Drawing on genealogical and demographic data, the analysis provides general but not comprehensive support for the prediction that average relatedness of immigrants to other group members increases as they age. In rare cases, natal members of the community also exhibit age-related increases in relatedness. We also find large variation in the proportion of female group members who are immigrants, beyond simple traditional considerations of patrilocality or matrilocality, which raises questions about the circumstances under which this hypothesis of female competition are met. We consider possible explanations for these heterogenous results, and we address methodological considerations that merit increased attention for research on kinship and reproductive conflict in human societies. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.

RevDate: 2020-01-13

Lynch EC, Lummaa V, Htut W, et al (2019)

Evolutionary significance of maternal kinship in a long-lived mammal.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1780):20180067.

Preferential treatment of kin is widespread across social species and is considered a central prerequisite to the evolution of cooperation through kin selection. Though it is well known that, among most social mammals, females will remain within their natal group and often bias social behaviour towards female maternal kin, less is known about the fitness consequences of these relationships. We test the fitness benefits of living with maternal sisters, measured by age-specific female reproduction, using an unusually large database of a semi-captive Asian elephant (Elephas maximus) population. This study system is particularly valuable to an exploration of reproductive trends in a long-lived mammal, because it includes life-history data that span multiple generations, enabling a study of the effects of kinship across a female's lifespan. We find that living near a sister significantly increased the likelihood of annual reproduction among young female elephants, and this effect was strongest when living near a sister 0-5 years younger. Our results show that fitness benefits gained from relationships with kin are age-specific, establish the basis necessary for the formation and maintenance of close social relationships with female kin, and highlight the adaptive importance of matriliny in a long-lived mammal. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.

RevDate: 2020-01-13

Holekamp KE, MA Sawdy (2019)

The evolution of matrilineal social systems in fissiped carnivores.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1780):20180065.

We review matrilineal relationships in the societies of fissiped mammalian carnivores, focusing on how the most complex of these may have evolved from simpler systems. Although competition for food is very intense at the trophic level occupied by most carnivores, and although most species of extant fissiped carnivores therefore lead solitary lives, some species show at least rudimentary clustering of maternal kin and matrilineal resource-sharing or transmission of critical resources between generations. The resources shared or transmitted range from individual food items and territories to entire networks of potential allies. The greatest elaboration of matrilineal relationships has occurred in two large carnivores, lions and spotted hyenas, which occur sympatrically throughout much of Africa. The societies of both these species apparently evolved in response to a shared suite of ecological conditions. The highly matrilineal societies of spotted hyenas are unique among carnivores and closely resemble the societies of many cercopithecine primates. The conditions favouring the evolution of matrilineal societies in carnivores include male-biased dispersal, female philopatry, the need for assistance in protecting or provisioning offspring, reliance on large or abundant prey, particularly in open habitat, high population density and kin-structured cooperative interactions that have strong positive effects on fitness. This article is part of the theme issue 'The evolution of female-biased kinship in humans and other mammals'.

RevDate: 2019-07-12

Ross L, Davies NG, A Gardner (2019)

How to make a haploid male.

Evolution letters, 3(2):173-184 pii:EVL3107.

Haplodiploidy has evolved repeatedly among invertebrates, and appears to be associated with inbreeding. Evolutionary biologists have long debated the possible benefits for females in diplodiploid species to produce haploid sons-beginning their population's transition to haplodiploidy-and whether inbreeding promotes or inhibits this transition. However, little attention has been given to what makes a haploid individual male rather than female, and whether the mechanism of sex determination may modulate the costs and benefits of male haploidy. We remedy this by performing a theoretical analysis of the origin and invasion of male haploidy across the full range of sex-determination mechanisms and sib-mating rates. We find that male haploidy is facilitated by three different mechanisms of sex determination-all involving male heterogamety-and impeded by the others. We also find that inbreeding does not pose an obvious evolutionary barrier, on account of a previously neglected sex-ratio effect whereby the production of haploid sons leads to an abundance of granddaughters that is advantageous in the context of inbreeding. We find empirical support for these predictions in a survey of sex determination and inbreeding across haplodiploids and their sister taxa.

RevDate: 2019-07-05

Ng YL (2019)

Active and Passive Facebook Use and Associated Costly Off-line Helping Behavior.

Psychological reports [Epub ahead of print].

RevDate: 2019-11-19

Leeks A, Dos Santos M, SA West (2019)

Transmission, relatedness, and the evolution of cooperative symbionts.

Journal of evolutionary biology, 32(10):1036-1045.

Cooperative interactions between species, termed mutualisms, play a key role in shaping natural ecosystems, economically important agricultural systems, and in influencing human health. Across different mutualisms, there is significant variation in the benefit that hosts receive from their symbionts. Empirical data suggest that transmission mode can help explain this variation: vertical transmission, where symbionts infect their host's offspring, leads to symbionts that provide greater benefits to their hosts than horizontal transmission, where symbionts leave their host and infect other hosts in the population. However, two different theoretical explanations have been given for this pattern: firstly, vertical transmission aligns the fitness interests of hosts and their symbionts; secondly, vertical transmission leads to increased relatedness between symbionts sharing a host, favouring cooperation between symbionts. We used a combination of analytical models and dynamic simulations to tease these factors apart, in order to compare their separate influences and see how they interact. We found that relatedness between symbionts sharing a host, rather than transmission mode per se, was the most important factor driving symbiont cooperation. Transmission mode mattered mainly because it determined relatedness. We also found evolutionary branching throughout much of our simulation, suggesting that a combination of transmission mode and multiplicity of infections could lead to the stable coexistence of different symbiont strategies.

RevDate: 2019-09-01

Bourke AF (2019)

Inclusive fitness and the major transitions in evolution.

Current opinion in insect science, 34:61-67.

Inclusive fitness theory is the leading framework for explaining the major transitions in evolution, whereby free-living subunits (e.g. cells, organisms) have cooperated to form new, higher-level units (e.g. organisms, eusocial societies). The theory has attracted considerable controversy. From a brief survey of the controversy's present status, I conclude that inclusive fitness theory continues to provide both a concept and a principled modelling tool of value for understanding social evolution, including major transitions. Turning to new developments in the study of major transitions, I describe work defining the point of occurrence of major transitions and, from inclusive fitness theory, the required conditions. I also suggest that it remains important to understand the evolution of individuality that occurs beyond such thresholds.

RevDate: 2019-12-24

Fromhage L, MD Jennions (2019)

The strategic reference gene: an organismal theory of inclusive fitness.

Proceedings. Biological sciences, 286(1904):20190459.

How to define and use the concept of inclusive fitness is a contentious topic in evolutionary theory. Inclusive fitness can be used to calculate selection on a focal gene, but it is also applied to whole organisms. Individuals are then predicted to appear designed as if to maximize their inclusive fitness, provided that certain conditions are met (formally when interactions between individuals are 'additive'). Here we argue that applying the concept of inclusive fitness to organisms is justified under far broader conditions than previously shown, but only if it is appropriately defined. Specifically, we propose that organisms should maximize the sum of their offspring (including any accrued due to the behaviour/phenotype of relatives), plus any effects on their relatives' offspring production, weighted by relatedness. By contrast, most theoreticians have argued that a focal individual's inclusive fitness should exclude any offspring accrued due to the behaviour of relatives. Our approach is based on the notion that long-term evolution follows the genome's 'majority interest' of building coherent bodies that are efficient 'vehicles' for gene propagation. A gene favoured by selection that reduces the propagation of unlinked genes at other loci (e.g. meiotic segregation distorters that lower sperm production) is eventually neutralized by counter-selection throughout the rest of the genome. Most phenotypes will therefore appear as if designed to maximize the propagation of any given gene in a focal individual and its relatives.

RevDate: 2019-06-10

Rautiala P, Helanterä H, M Puurtinen (2019)

Extended haplodiploidy hypothesis.

Evolution letters, 3(3):263-270 pii:EVL3119.

Evolution of altruistic behavior was a hurdle for the logic of Darwinian evolution. Soon after Hamilton formalized the concept of inclusive fitness, which explains how altruism can evolve, he suggested that the high sororal relatedness brought by haplodiploidy could be why Hymenopterans have a high prevalence in eusocial species, and why helpers in Hymenoptera are always female. Later it was noted that in order to capitalize on the high sororal relatedness, helpers would need to direct help toward sisters, and this would bias the population sex ratio. Under a 1:3 males:females sex ratio, the inclusive fitness valuation a female places on her sister, brother, and an own offspring are equal-apparently removing the benefit of helping over independent reproduction. Based on this argumentation, haplodiploidy hypothesis has been considered a red herring. However, here we show that when population sex ratio, cost of altruism, and population growth rate are considered together, haplodiploidy does promote female helping even with female-biased sex ratio, due the lowered cost of altruism in such populations. Our analysis highlights the need to re-evaluate the role of haplodiploidy in the evolution of helping, and the importance of fully exploring the model assumptions when comparing interactions of population sex ratios and social behaviors.

RevDate: 2019-12-17
CmpDate: 2019-12-11

Lenárt P, Zlámal F, Kukla L, et al (2019)

Sibling relatedness rather than father absence predicts earlier age at menarche in ELSPAC cohort.

Biology letters, 15(6):20190091.

Many studies during the past 50 years have found an association between father absence and earlier menarche. In connection with these findings, several evolutionary theories assume that father absence is a causal factor accelerating reproductive development. However, a recent study analysing data from the Avon Longitudinal Study of Parents and Children (ALSPAC) found that father absence does not predict age at menarche when adjusted for sibling relatedness. In this study, we have replicated these results in the Czech section of the European Longitudinal Study of Pregnancy and Childhood (ELSPAC), which used the same questionnaires as ALSPAC to study a geographically distinct population. Our results support the conclusion that sibling relatedness rather than father absence predicts age at menarche. Furthermore, our results show that age at menarche in 1990s UK and Czech cohorts is very similar despite socioeconomic differences between the two countries.

RevDate: 2019-11-20

Ostrowski EA (2019)

Enforcing Cooperation in the Social Amoebae.

Current biology : CB, 29(11):R474-R484.

Cooperation has been essential to the evolution of biological complexity, but many societies struggle to overcome internal conflicts and divisions. Dictyostelium discoideum, or the social amoeba, has been a useful model system for exploring these conflicts and how they can be resolved. When starved, these cells communicate, gather into groups, and build themselves into a multicellular fruiting body. Some cells altruistically die to form the rigid stalk, while the remainder sit atop the stalk, become spores, and disperse. Evolutionary theory predicts that conflict will arise over which cells die to form the stalk and which cells become spores and survive. The power of the social amoeba lies in the ability to explore how cooperation and conflict work across multiple levels, ranging from proximate mechanisms (how does it work?) to ultimate evolutionary answers (why does it work?). Recent studies point to solutions to the problem of ensuring fairness, such as the ability to suppress selfishness and to recognize and avoid unrelated individuals. This work confirms a central role for kin selection, but also suggests new explanations for how social amoebae might enforce cooperation. New approaches based on genomics are also enabling researchers to decipher for the first time the evolutionary history of cooperation and conflict and to determine its role in shaping the biology of multicellular organisms.

RevDate: 2019-11-20

Apicella CL, JB Silk (2019)

The evolution of human cooperation.

Current biology : CB, 29(11):R447-R450.

Darwin viewed cooperation as a perplexing challenge to his theory of natural selection. Natural selection generally favors the evolution of behaviors that enhance the fitness of individuals. Cooperative behavior, which increases the fitness of a recipient at the expense of the donor, contradicts this logic. William D. Hamilton helped to solve the puzzle when he showed that cooperation can evolve if cooperators direct benefits selectively to other cooperators (i.e. assortment). Kinship, group selection and the previous behavior of social partners all provide mechanisms for assortment (Figure 1), and kin selection and reciprocal altruism are the foundation of the kinds of cooperative behavior observed in many animals. Humans also bias cooperation in favor of kin and reciprocating partners, but the scope, scale, and variability of human cooperation greatly exceed that of other animals. Here, we introduce derived features of human cooperation in the context in which they originally evolved, and discuss the processes that may have shaped the evolution of our remarkable capacity for cooperation. We argue that culturally-evolved norms that specify how people should behave provide an evolutionarily novel mechanism for assortment, and play an important role in sustaining derived properties of cooperation in human groups.

RevDate: 2019-11-20

Kay T, Lehmann L, L Keller (2019)

Kin selection and altruism.

Current biology : CB, 29(11):R438-R442.

Natural selection is predicated on the 'struggle for existence': life is short, cruel and, whether through predation, disease or starvation, often ends traumatically. It would seem that in such a dog-eat-dog world, organisms ought to act selfishly, and avoid reducing their fitness (expected survival and reproductive success) by expending time and energy helping others. Put another way, alleles that increase the probability of altruism - a behavior whose expression increases the fitness of recipients while decreasing that of the actor - should decrease in frequency across generations and ultimately disappear.

RevDate: 2019-11-20

Birch J (2019)

Are kin and group selection rivals or friends?.

Current biology : CB, 29(11):R433-R438.

Kin selection and group selection were once seen as competing explanatory hypotheses but now tend to be seen as equivalent ways of describing the same basic idea. Yet this 'equivalence thesis' seems not to have brought proponents of kin selection and group selection any closer together. This may be because the equivalence thesis merely shows the equivalence of two statistical formalisms without saying anything about causality. W.D. Hamilton was the first to derive an equivalence result of this type. Yet Hamilton was aware of its limitations, and saw that, while illuminating, it papered over some biologically important distinctions. Attending to these distinctions leads to the concept of 'K-G space', which helps us see where the biological disagreements between proponents of kin selection and group selection really lie.

RevDate: 2019-12-22

Southon RJ, Bell EF, Graystock P, et al (2019)

High indirect fitness benefits for helpers across the nesting cycle in the tropical paper wasp Polistes canadensis.

Molecular ecology, 28(13):3271-3284.

Explaining the evolution of helping behaviour in the eusocial insects where nonreproductive ("worker") individuals help raise the offspring of other individuals ("queens") remains one of the most perplexing phenomena in the natural world. Polistes paper wasps are popular study models, as workers retain the ability to reproduce: such totipotency is likely representative of the early stages of social evolution. Polistes is thought to have originated in the tropics, where seasonal constraints on reproductive options are weak and social groups are effectively perennial. Yet, most Polistes research has focused on nontropical species, where seasonality causes family groups to disperse; cofoundresses forming new nests the following spring are often unrelated, leading to the suggestion that direct fitness through nest inheritance is key in the evolution of helping behaviour. Here, we present the first comprehensive genetic study of social structure across the perennial nesting cycle of a tropical Polistes-Polistes canadensis. Using both microsatellites and newly developed single nucleotide polymorphism markers, we show that adult cofoundresses are highly related and that brood production is monopolized by a single female across the nesting cycle. Nonreproductive cofoundresses in tropical Polistes therefore have the potential to gain high indirect fitness benefits as helpers from the outset of group formation, and these benefits persist through the nesting cycle. Direct fitness may have been less important in the origin of Polistes sociality than previously suggested. These findings stress the importance of studying a range of species with diverse life history and ecologies when considering the evolution of reproductive strategies.

RevDate: 2019-11-20

Hitchcock TJ, Paracchini S, A Gardner (2019)

Genomic Imprinting As a Window into Human Language Evolution.

BioEssays : news and reviews in molecular, cellular and developmental biology, 41(6):e1800212.

Humans spend large portions of their time and energy talking to one another, yet it remains unclear whether this activity is primarily selfish or altruistic. Here, it is shown how parent-of-origin specific gene expression-or "genomic imprinting"-may provide an answer to this question. First, it is shown why, regarding language, only altruistic or selfish scenarios are expected. Second, it is pointed out that an individual's maternal-origin and paternal-origin genes may have different evolutionary interests regarding investment into language, and that this intragenomic conflict may drive genomic imprinting which-as the direction of imprint depends upon whether investment into language is relatively selfish or altruistic-may be used to discriminate between these two possibilities. Third, predictions concerning the impact of various mutations and epimutations at imprinted loci on language pathologies are derived. In doing so, a framework is developed that highlights avenues for using intragenomic conflicts to investigate the evolutionary drivers of language.

RevDate: 2019-11-20

Shakhar K (2019)

The Inclusive Behavioral Immune System.

Frontiers in psychology, 10:1004.

Although living in social groups offers many advantages, it comes at a cost of increased transmissible disease. The behavioral immune system (BIS) is thought to have evolved as a first line of defense against such infections. It acts by minimizing the contact of yet uninfected hosts with potential pathogens. The BIS has been observed in a wide range of animals including insects, amphibians and mammals, but most research has focused on humans where the BIS is guided by complex cognitive and emotional processing. When researchers discuss the evolutionary origin of the BIS, they assess how it raises individual fitness. What would happen though if we shift our attention to the evolutionary unit of selection - the gene? Success would be measured as the change in the gene's prevalence in the entire population, and additional behaviors would come to our attention - those that benefit relatives, i.e., behaviors that raise inclusive fitness. One widely-recognized example of the inclusive BIS is social immunity, which is prevalent among eusocial organisms such as bees and ants. Their colonies engage in a collaborative protective behavior such as grooming and the removal of infected members from the nest. Another example may be sickness behavior, which includes the behavioral, cognitive and emotional symptoms that accompany infection, such as fatigue, and loss of appetite and social interest. My colleague and I recently suggested that sickness behavior has evolved because it reduces the direct and indirect contact between an infected host and its healthy kin - improving inclusive fitness. These additional behaviors are not carried out by the healthy individuals, but rather by whole communities in the first case, and by already infected individuals in the second. Since they step beyond the classical definition of BIS, it may be useful to broaden the term to the inclusive behavioral immune system.

RevDate: 2019-11-20

Duncan C, Gaynor D, Clutton-Brock T, et al (2019)

The Evolution of Indiscriminate Altruism in a Cooperatively Breeding Mammal.

The American naturalist, 193(6):841-851.

Kin selection theory suggests that altruistic behaviors can increase the fitness of altruists when recipients are genetic relatives. Although selection can favor the ability of organisms to preferentially cooperate with close kin, indiscriminately helping all group mates may yield comparable fitness returns if relatedness within groups is very high. Here, we show that meerkats (Suricata suricatta) are largely indiscriminate altruists who do not alter the amount of help provided to pups or group mates in response to their relatedness to them. We present a model showing that indiscriminate altruism may yield greater fitness payoffs than kin discrimination where most group members are close relatives and errors occur in the estimation of relatedness. The presence of errors in the estimation of relatedness provides a feasible explanation for associations between kin discriminative helping and group relatedness in eusocial and cooperatively breeding animals.

RevDate: 2019-07-17

Jänig S, Weiß BM, Birkemeyer C, et al (2019)

Comparative chemical analysis of body odor in great apes.

American journal of primatology, 81(6):e22976.

Olfaction is important across the animal kingdom for transferring information on, for example, species, sex, group membership, or reproductive parameters. Its relevance has been established in primates including humans, yet research on great apes still is fragmentary. Observational evidence indicates that great apes use their sense of smell in various contexts, but the information content of their body odor has not been analyzed. Our aim was therefore to compare the chemical composition of body odor in great ape species, namely Sumatran orangutans (Pongo abelii (Lesson, 1827), one adult male, five adult females, four nonadults), Western lowland gorillas (Gorilla gorilla gorilla (Savage, 1847), one adult male, two adult females, one nonadult), common chimpanzees (Pan troglodytes (Blumenbach, 1775), four adult males, nine adult females, four nonadults), and bonobos (Pan paniscus (Schwarz, 1929), two adult males, four adult females, two nonadults). We collected 195 samples (five per individual) of 39 captive individuals using cotton swabs and analyzed them using gas chromatography mass spectrometry. We compared the sample richness and intensity, similarity of chemical composition, and relative abundance of compounds. Results show that species, age, and potentially sex have an impact on the variance between odor profiles. Richness and intensity varied significantly between species (gorillas having the highest, bonobos the lowest richness and intensity), and with age (both increasing with age). Richness and intensity did not vary between sexes. Odor samples of the same species were more similar to each other than samples of different species. Among all compounds identified some were associated with age (N = 7), sex (N = 6), and species-related (N = 37) variance. Our study contributes to the basic understanding of olfactory communication in hominids by showing that the chemical composition of body odor varies across species and individuals, containing potentially important information for social communication.

RevDate: 2019-11-20

Geist KS, Strassmann JE, DC Queller (2019)

Family quarrels in seeds and rapid adaptive evolution in Arabidopsis.

Proceedings of the National Academy of Sciences of the United States of America, 116(19):9463-9468.

Evolutionary conflict can drive rapid adaptive evolution, sometimes called an arms race, because each party needs to respond continually to the adaptations of the other. Evidence for such arms races can sometimes be seen in morphology, in behavior, or in the genes underlying sexual interactions of host-pathogen interactions, but is rarely predicted a priori. Kin selection theory predicts that conflicts of interest should usually be reduced but not eliminated among genetic relatives, but there is little evidence as to whether conflict within families can drive rapid adaptation. Here we test multiple predictions about how conflict over the amount of resources an offspring receives from its parent would drive rapid molecular evolution in seed tissues of the flowering plant Arabidopsis As predicted, there is more adaptive evolution in genes expressed in Arabidopsis seeds than in other specialized organs, more in endosperms and maternal tissues than in embryos, and more in the specific subtissues involved in nutrient transfer. In the absence of credible alternative hypotheses, these results suggest that kin selection and conflict are important in plants, that the conflict includes not just the mother and offspring but also the triploid endosperm, and that, despite the conflict-reducing role of kinship, family members can engage in slow but steady tortoise-like arms races.

RevDate: 2019-10-10

Sbarra DA, Briskin JL, RB Slatcher (2019)

Smartphones and Close Relationships: The Case for an Evolutionary Mismatch.

Perspectives on psychological science : a journal of the Association for Psychological Science, 14(4):596-618.

This article introduces and outlines the case for an evolutionary mismatch between smartphones and the social behaviors that help form and maintain close social relationships. As psychological adaptations that enhance human survival and inclusive fitness, self-disclosure and responsiveness evolved in the context of small kin networks to facilitate social bonds, promote trust, and enhance cooperation. These adaptations are central to the development of attachment bonds, and attachment theory is a middle-level evolutionary theory that provides a robust account of the ways human bonding provides for reproductive and inclusive fitness. Evolutionary mismatches operate when modern contexts cue ancestral adaptations in a manner that does not provide for their adaptive benefits. We argue that smartphones and their affordances, although highly beneficial in many circumstances, cue humans' evolved needs for self-disclosure and responsiveness across broad virtual networks and, in turn, have the potential to undermine immediate interpersonal interactions. We review emerging evidence on the topic of technoference, which is defined as the ways in which smartphone use may interfere with or intrude into everyday social interactions. The article concludes with an empirical agenda for advancing the integrative study of smartphones, intimacy processes, and close relationships.

RevDate: 2019-07-11

Levin SR, A Grafen (2019)

Inclusive fitness is an indispensable approximation for understanding organismal design.

Evolution; international journal of organic evolution, 73(6):1066-1076.

For some decades most biologists interested in design have agreed that natural selection leads to organisms acting as if they are maximizing a quantity known as "inclusive fitness." This maximization principle has been criticized on the (uncontested) grounds that other quantities, such as offspring number, predict gene frequency changes accurately in a wider range of mathematical models. Here, we adopt a resolution offered by Birch, who accepts the technical difficulties of establishing inclusive fitness maximization in a fully general model, while concluding that inclusive fitness is still useful as an organizing framework. We set out in more detail why inclusive fitness is such a practical and powerful framework, and provide verbal and conceptual arguments for why social biology would be more or less impossible without it. We aim to help mathematicians understand why social biologists are content to use inclusive fitness despite its theoretical weaknesses. Here, we also offer biologists practical advice for avoiding potential pitfalls.

RevDate: 2019-11-08

Cotter SC, Pincheira-Donoso D, R Thorogood (2019)

Defences against brood parasites from a social immunity perspective.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1769):20180207.

Parasitic interactions are so ubiquitous that all multicellular organisms have evolved a system of defences to reduce their costs, whether the parasites they encounter are the classic parasites which feed on the individual, or brood parasites which usurp parental care. Many parallels have been drawn between defences deployed against both types of parasite, but typically, while defences against classic parasites have been selected to protect survival, those against brood parasites have been selected to protect the parent's inclusive fitness, suggesting that the selection pressures they impose are fundamentally different. However, there is another class of defences against classic parasites that have specifically been selected to protect an individual's inclusive fitness, known as social immunity. Social immune responses include the anti-parasite defences typically provided for others in kin-structured groups, such as the antifungal secretions produced by termite workers to protect the brood. Defences against brood parasites, therefore, are more closely aligned with social immune responses. Much like social immunity, host defences against brood parasitism are employed by a donor (a parent) for the benefit of one or more recipients (typically kin), and as with social defences against classic parasites, defences have therefore evolved to protect the donor's inclusive fitness, not the survival or ultimately the fitness of individual recipients This can lead to severe conflicts between the different parties, whose interests are not always aligned. Here, we consider defences against brood parasitism in the light of social immunity, at different stages of parasite encounter, addressing where conflicts occur and how they might be resolved. We finish with considering how this approach could help us to address longstanding questions in our understanding of brood parasitism. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.

RevDate: 2019-11-08

Gloag R, M Beekman (2019)

The brood parasite's guide to inclusive fitness theory.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1769):20180198.

Hamilton's theory of inclusive fitness provides a framework for understanding the evolution of social behaviour between kin, including parental and alloparental care. Brood parasitism is a reproductive tactic in which parasites exploit the care of other individuals of the same species (conspecific parasitism) or different species (interspecific parasitism) to rear their brood. Here, drawing from examples in birds and social insects, we identify two insights into brood parasitism that stem from inclusive fitness theory. First, the kin structure within nests, or between neighbouring nests, can create a niche space favouring the evolution of conspecific parasitism. For example, low average relatedness within social insect nests can increase selection for reproductive cheats. Likewise, high average relatedness between adjacent nests of some birds can increase a female's tolerance of parasitism by her neighbour. Second, intrabrood conflict will be high in parasitized broods, from the perspective of both parasite and host young, relative to unparasitized broods. We also discuss offspring recognition by hosts as an example of discrimination in a kin-selected social behaviour. We conclude that the inclusive fitness framework is instructive for understanding aspects of brood parasite and host evolution. In turn, brood parasites present some unique opportunities to test the predictions of inclusive fitness theory. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.

RevDate: 2019-11-13

Vitikainen EIK, Thompson FJ, Marshall HH, et al (2019)

Live long and prosper: durable benefits of early-life care in banded mongooses.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1770):20180114.

Kin selection theory defines the conditions for which altruism or 'helping' can be favoured by natural selection. Tests of this theory in cooperatively breeding animals have focused on the short-term benefits to the recipients of help, such as improved growth or survival to adulthood. However, research on early-life effects suggests that there may be more durable, lifelong fitness impacts to the recipients of help, which in theory should strengthen selection for helping. Here, we show in cooperatively breeding banded mongooses (Mungos mungo) that care received in the first 3 months of life has lifelong fitness benefits for both male and female recipients. In this species, adult helpers called 'escorts' form exclusive one-to-one caring relationships with specific pups (not their own offspring), allowing us to isolate the effects of being escorted on later reproduction and survival. Pups that were more closely escorted were heavier at sexual maturity, which was associated with higher lifetime reproductive success for both sexes. Moreover, for female offspring, lifetime reproductive success increased with the level of escorting received per se, over and above any effect on body mass. Our results suggest that early-life social care has durable benefits to offspring of both sexes in this species. Given the well-established developmental effects of early-life care in laboratory animals and humans, we suggest that similar effects are likely to be widespread in social animals more generally. We discuss some of the implications of durable fitness benefits for the evolution of intergenerational helping in cooperative animal societies, including humans. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

RevDate: 2019-11-13

Kuijper B, RA Johnstone (2019)

The evolution of early-life effects on social behaviour-why should social adversity carry over to the future?.

Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 374(1770):20180111.

Numerous studies have shown that social adversity in early life can have long-lasting consequences for social behaviour in adulthood, consequences that may in turn be propagated to future generations. Given these intergenerational effects, it is puzzling why natural selection might favour such sensitivity to an individual's early social environment. To address this question, we model the evolution of social sensitivity in the development of helping behaviours, showing that natural selection indeed favours individuals whose tendency to help others is dependent on early-life social experience. In organisms with non-overlapping generations, we find that natural selection can favour positive social feedbacks, in which individuals who received more help in early life are also more likely to help others in adulthood, while individuals who received no early-life help develop low tendencies to help others later in life. This positive social sensitivity is favoured because of an intergenerational relatedness feedback: patches with many helpers tend to be more productive, leading to higher relatedness within the local group, which in turn favours higher levels of help in the next generation. In organisms with overlapping generations, this positive feedback is less likely to occur, and those who received more help may instead be less likely to help others (negative social feedback). We conclude that early-life social influences can lead to strong between-individual differences in helping behaviour, which can take different forms dependent on the life history in question. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

RevDate: 2019-12-10
CmpDate: 2019-09-05

Schindler S, AN Radford (2018)

Factors influencing within-group conflict over defence against conspecific outsiders seeking breeding positions.

Proceedings. Biological sciences, 285(1893):20181669.

In social species, groups face a variety of threats from conspecific outsiders. Defensive actions are therefore common, but there is considerable variation in which individuals contribute and to what extent. There has been some theoretical exploration of this variation when the defence is of shared resources, but the relative contributions when a single intruder threatens a particular breeding position have received less attention. Defensive actions are costly, both for the individual and dependent young, and contributions are likely to differ depending on individual sex, rank and size, current breeding stage, infanticide risk and relatedness levels. Here, we model analytically the relative fitness benefits of different group members to engaging in defence against individual intruders and determine when within-group conflicts of interest might arise over these defensive contributions. Conflicts of interest between the challenged breeder and other group members depend on relatedness to the brood and the potential relatedness reduction if an intruder acquires breeding status. Conflicts are more likely to occur when there is a low chance of winning the contest, low infanticide rates, inefficient defence from helpers, a long remaining brood-dependency period and high external (non-contest-related) mortality. Our work can help explain variation in defensive actions against out-group threats.

RevDate: 2020-01-17
CmpDate: 2020-01-17

Faria GS, Varela SAM, A Gardner (2019)

The social evolution of sleep: sex differences, intragenomic conflicts and clinical pathologies.

Proceedings. Biological sciences, 286(1894):20182188.

Sleep appears to be essential for most animals, including humans. Accordingly, individuals who sacrifice sleep are expected to incur costs and so should only be evolutionarily favoured to do this when these costs are offset by other benefits. For instance, a social group might benefit from having some level of wakefulness during the sleeping period if this guards against possible threats. Alternatively, individuals might sacrifice sleep in order to gain an advantage over mate competitors. Here, we perform a theoretical analysis of the social evolutionary pressures that drive investment into sleep versus wakefulness. Specifically, we: investigate how relatedness between social partners may modulate sleeping strategies, depending upon whether sleep sacrifice is selfish or altruistic; determine the conditions under which the sexes are favoured to adopt different sleeping strategies; identify the potential for intragenomic conflict between maternal-origin versus paternal-origin genes regarding an individual's sleeping behaviour; translate this conflict into novel and readily testable predictions concerning patterns of gene expression; and explore the concomitant effects of different kinds of mutations, epimutations, and uniparental disomies in relation to sleep disorders and other clinical pathologies. Our aim is to provide a theoretical framework for future empirical data and stimulate further research on this neglected topic.

RevDate: 2019-10-23
CmpDate: 2019-10-23

Humphreys RK, GD Ruxton (2019)

Adaptive suicide: is a kin-selected driver of fatal behaviours likely?.

Biology letters, 15(2):20180823.

While several manipulated host behaviours are accepted as extended phenotypes of parasites, there remains debate over whether other altered behaviours in hosts following parasitic invasion represent cases of parasite manipulation, host defence or the pathology of infection. One particularly controversial subject is 'suicidal behaviour' in infected hosts. The host-suicide hypothesis proposes that host death benefits hosts doomed to reduced direct fitness by protecting kin from parasitism and therefore increasing inclusive fitness. However, adaptive suicide has been difficult to demonstrate conclusively as a host adaptation in studies on social or clonal insects, for whom high relatedness should enable greater inclusive fitness benefits. Following discussion of empirical and theoretical works from a behavioural ecology perspective, this review finds that the most persuasive evidence for selection of adaptive suicide comes from bacteria. Despite a focus on parasites, driven by the existing literature, the potential for the evolution of adaptive suicidal behaviour in hosts is also considered to apply to cases of infection by pathogens, provided that the disease has a severe effect on direct fitness and that suicidal behaviour can affect pathogen transmission dynamics. Suggestions are made for future research and a broadening of the possible implications for coevolution between parasites and hosts.

RevDate: 2019-11-20

Spring S, Lehner M, Huber L, et al (2019)

Oviposition and father presence reduce clutch cannibalism by female poison frogs.

Frontiers in zoology, 16:8 pii:304.

Background: The consumption of conspecific young by adult individuals is a common phenomenon across various animal taxa. Possible adaptive benefits of such behaviour include the acquisition of nutrients, decreased competition for one's own offspring, and/or increased mating opportunities. Clutch cannibalism has occasionally been observed in several species of Neotropical poison frogs, but the circumstances under which this behaviour occurs has rarely been investigated experimentally. Recent experiments with the poison frog Allobates femoralis have shown that males indiscriminately transport all clutches located inside their own territory to bodies of water, but become highly cannibalistic when taking over a new territory. Females are able to indirectly discriminate between their own and foreign clutches by location and take over transport duties of their own clutches only in the absence of the father. Cannibalism by A. femoralis females has not been previously observed. We thus asked if, and under which circumstances, cannibalism of unrelated clutches by female A. femoralis would occur, by manipulating the presence of the clutch's father, the female's own reproductive state, and the female's familiarity with the environment.

Results: Females clearly cannibalize foreign clutches. Cannibalism was most pronounced when the female had not recently produced her own clutch and the father of the foreign clutch was absent. The female's familiarity with the area had no significant influence on the likelihood of cannibalism to occur.

Conclusions: Our data indicate that both previous oviposition and the father's presence reduce cannibalistic behaviour in A. femoralis females. Cannibalistic females may gain nutritional benefits or enhanced inclusive fitness by preying on other females' offspring. The finding that the father's presence at the clutch site/territory was sufficient to reduce cannibalism by females suggests a prominent role of male territoriality for the evolution of male parental care.

RevDate: 2019-12-17
CmpDate: 2019-12-06

Smith AR, Kapheim KM, Kingwell CJ, et al (2019)

A split sex ratio in solitary and social nests of a facultatively social bee.

Biology letters, 15(4):20180740.

A classic prediction of kin selection theory is that a mixed population of social and solitary nests of haplodiploid insects should exhibit a split sex ratio among offspring: female biased in social nests, male biased in solitary nests. Here, we provide the first evidence of a solitary-social split sex ratio, using the sweat bee Megalopta genalis (Halictidae). Data from 2502 offspring collected from naturally occurring nests across 6 years spanning the range of the M. genalis reproductive season show that despite significant yearly and seasonal variation, the offspring sex ratio of social nests is consistently more female biased than in solitary nests. This suggests that split sex ratios may facilitate the evolutionary origins of cooperation based on reproductive altruism via kin selection.

RevDate: 2019-11-22
CmpDate: 2019-11-22

Atchison BJ, DL Goodwin (2019)

"My Child May Be Ready, but I Am Not": Parents' Experiences of Their Children's Transition to Inclusive Fitness Settings.

Adapted physical activity quarterly : APAQ, 36(2):282-301.

Parents play an essential role in the transition from separate physical activity programs to inclusive settings for their children. The purpose of this study was to explore experiences of parents as they anticipate and prepare for their children experiencing disability to transition, understand strategies used to address transition, and gain insights into the supports important to families during transition. Using an interpretative phenomenological analysis research approach, semistructured one-on-one interviews were conducted with 8 parents whose children were undergoing the transition from separate to inclusive community fitness contexts. Four themes described the experiences of parents as they anticipated, prepared for, and supported their child to transition: My child may be ready, but I am not; fear of outside judgment; playing by their rules; and reframing our thinking. Using Schlossberg's model, the tensions parents faced as they negotiated new roles, relationships, routines, and assumptions as they moved through the transition process were uncovered. The parents experienced transition alongside their children, providing insights for fitness and health-promotion professionals. Without preparation for transition, apprehensions and hesitancy may postpone or prevent their children's transition to community programs.

RevDate: 2019-11-20

David-Barrett T (2019)

Network Effects of Demographic Transition.

Scientific reports, 9(1):2361 pii:10.1038/s41598-019-39025-4.

Traditional human societies use two of biology's solutions to reduce free-riding: by collaborating with relatives, they rely on the mechanism of kin-selection, and by forming highly clustered social kin-networks, they can efficiently use reputation dynamics. Both of these solutions assume the presence of relatives. This paper shows how social networks change during demographic transition. With falling fertility, there are fewer children that could be relatives to one another. As the missing kin are replaced by non-kin friends, local clustering in the social network drops. This effect is compounded by increasing population size, characteristic of demographic transition. The paper also shows that the speed at which reputation spreads in the network slows down due to both falling fertility and increasing group size. Thus, demographic transition weakens both mechanisms for eliminating free-riders: there are fewer relatives around, and reputation spreads slower. This new link between falling fertility and the altered structure of the social network offers novel interpretations of the origins of legal institutions, the Small World phenomenon, the social impact of urbanisation, and the birds-of-a-feather friendship choice heuristic.

RevDate: 2019-11-18

Engelhardt SC, Bergeron P, Gagnon A, et al (2019)

Using Geographic Distance as a Potential Proxy for Help in the Assessment of the Grandmother Hypothesis.

Current biology : CB, 29(4):651-656.e3.

Life-history theory predicts that selection could favor the decoupling of somatic and reproductive senescence if post-reproductive lifespan (PRLS) provides additional indirect fitness benefits [1, 2]. The grandmother hypothesis proposes that prolonged PRLS evolved because post-reproductive grandmothers gain inclusive fitness benefits by helping their daughters and grandchildren [3, 4]. Because most historical human data do not report direct evidence of help, we hypothesized that geographic distance between individuals may be inversely related to their capacity to help. Using an exceptionally detailed dataset of pre-industrial French settlers in the St. Lawrence Valley during the 17th and 18th centuries, we assessed the potential for grandmothers to improve their inclusive fitness by helping their descendants, and we evaluated how this effect varied with geographic distance, ranging between 0 and 325 km, while accounting for potential familial genetic and environmental effects [5-9]. Grandmothers (F0) who were alive allowed their daughters (F1) to increase their number of offspring (F2) born by 2.1 and to increase their number of offspring surviving to 15 years of age by 1.1 compared to when grandmothers were dead. However, the age at first reproduction was not influenced by the life status (alive or dead) of grandmothers. As geographic distance increased, the number of offspring born and lifetime reproductive success decreased, while the age at first reproduction increased, despite the grandmother being alive in these analyses. Our study suggests that geographic proximity has the potential to modulate inclusive fitness, supporting the grandmother hypothesis, and to contribute to our understanding of the evolution of PRLS.

RevDate: 2019-11-18

Chapman SN, Pettay JE, Lummaa V, et al (2019)

Limits to Fitness Benefits of Prolonged Post-reproductive Lifespan in Women.

Current biology : CB, 29(4):645-650.e3.

Recent advances in medicine and life-expectancy gains have fueled multidisciplinary research into the limits of human lifespan [1-3]. Ultimately, how long humans can live for may depend on selection favoring extended longevity in our evolutionary past [4]. Human females have an unusually extended post-reproductive lifespan, which has been explained by the fitness benefits provided from helping to raise grandchildren following menopause [5, 6]. However, formal tests of whether such grandmothering benefits wane with grandmother age and explain the observed length of post-reproductive lifespan are missing. This is critical for understanding prevailing selection pressures on longevity but to date has been overlooked as a possible mechanism driving the evolution of lifespan. Here, we use extensive data from pre-industrial humans to show that fitness gains from grandmothering are dependent on grandmother age, affecting selection on the length of post-reproductive lifespan. We find both opportunities and ability to help grandchildren declined with age, while the hazard of death of women increased greatly in their late 60s and 70s compared to menopausal ages, together implying waning selection on subsequent longevity. The presence of maternal grandmothers aged 50-75 increased grandchild survival after weaning, confirming the fitness advantage of post-reproductive lifespan. However, co-residence with paternal grandmothers aged 75+ was detrimental to grandchild survival, with those grandmothers close to death and presumably in poorer health particularly associated with lower grandchild survival. The age limitations of gaining inclusive fitness from grandmothering suggests that grandmothering can select for post-reproductive longevity only up to a certain point.

RevDate: 2019-12-19
CmpDate: 2019-12-19

Almond EJ, Huggins TJ, Crowther LP, et al (2019)

Queen Longevity and Fecundity Affect Conflict with Workers over Resource Inheritance in a Social Insect.

The American naturalist, 193(2):256-266.

Resource inheritance is a major source of conflict in animal societies. However, the assumptions and predictions of models of conflict over resource inheritance have not been systematically tested within a single system. We developed an inclusive fitness model for annual eusocial Hymenoptera that predicts a zone of conflict in which future reproductive workers are selected to enforce nest inheritance before the queen is selected to cede the nest. We experimentally tested key elements of this model in the bumblebee Bombus terrestris. In colonies from which queens were sequentially removed, queen tenure was significantly negatively associated with worker male production, confirming that workers gain direct fitness by usurping the queen. In unmanipulated colonies, queen fecundity decreased significantly over the latter part of the colony cycle, confirming that workers' indirect fitness from maintaining queens declines over time. Finally, in an experiment simulating loss of queen fecundity by removal of queens' eggs, worker-to-queen aggression increased significantly and aggressive workers were significantly more likely to become egg layers, consistent with workers monitoring queen fecundity to assess the net benefit of future reproduction. Overall, by upholding key assumptions and predictions of the model, our results provide novel empirical support for kin-selected conflict over resource inheritance.

RevDate: 2019-11-20

Amici F, Sánchez-Amaro A, Sebastián-Enesco C, et al (2019)

The word order of languages predicts native speakers' working memory.

Scientific reports, 9(1):1124 pii:10.1038/s41598-018-37654-9.

The relationship between language and thought is controversial. One hypothesis is that language fosters habits of processing information that are retained even in non-linguistic domains. In left-branching (LB) languages, modifiers usually precede the head, and real-time sentence comprehension may more heavily rely on retaining initial information in working memory. Here we presented a battery of working memory and short-term memory tasks to adult native speakers of four LB and four right-branching (RB) languages from Africa, Asia and Europe. In working memory tasks, LB speakers were better than RB speakers at recalling initial stimuli, but worse at recalling final stimuli. Our results show that the practice of parsing sentences in specific directions due to the syntax and word order of our native language not only predicts the way we remember words, but also other non-linguistic stimuli.

RevDate: 2020-01-09
CmpDate: 2020-01-09

Grueter CC, Hale J, Jin R, et al (2019)

Infant handling by female mountain gorillas: Establishing its frequency, function, and (ir)relevance for life history evolution.

American journal of physical anthropology, 168(4):744-749.

OBJECTIVES: Infant handling describes cases in which youngsters are temporarily removed from the care of their mothers and "taken care of" (held, carried, etc.) by other conspecifics. Handlers may gain indirect fitness benefits from these actions and can practice mothering skills, thereby improving the odds of survival of their own infants. Great apes are notable for displaying little infant handling. Apart from anecdotal observations, no published data exist on infant handling in wild mountain gorillas. We tested two of the most pertinent explanations ("kin selection" and "learning to mother") in a wild population of mountain gorillas in Rwanda. We predicted that (a) nulliparous females would exhibit infant handling (i.e., carrying) more than parous females and (b) maternal kin would exhibit more infant handling than nonkin.

METHODS: We collated 8 years of data on infant carrying behavior collected in 13 groups monitored by the Dian Fossey Gorilla Fund's Karisoke Research Center.

RESULTS: Infant handling is an infrequent behavior (1,783 instances over 25,600 observation hours). A strong positive effect of relatedness and handler parity on the frequency of infant handling emerged.

CONCLUSIONS: While the nature of handler-infant interactions (affiliative, abusive, etc.) remains unstudied, they could constitute alloparental care and could therefore attenuate maternal energetic burden and ultimately allow increased birth rates. However, the rarity of this behavior makes it an unlikely contributor to mountain gorillas' relatively short interbirth intervals.

RevDate: 2019-07-09
CmpDate: 2019-07-09

Bose APH, Henshaw JM, Zimmermann H, et al (2019)

Inclusive fitness benefits mitigate costs of cuckoldry to socially paired males.

BMC biology, 17(1):2 pii:10.1186/s12915-018-0620-6.

BACKGROUND: In socially monogamous species, reproduction is not always confined to paired males and females. Extra-pair males commonly also reproduce with paired females, which is traditionally thought to be costly to the females' social partners. However, we suggest that when the relatedness between reproducing individuals is considered, cuckolded males can suffer lower fitness losses than otherwise expected, especially when the rate of cuckoldry is high. We combine theoretical modeling with a detailed genetic study on a socially monogamous wild fish, Variabilichromis moorii, which displays biparental care despite exceptionally high rates of extra-pair paternity.

RESULTS: We measured the relatedness between all parties involved in V. moorii spawning events (i.e. between males and females in social pairs, females and their extra-pair partners, and paired males and their cuckolders), and we reveal that males are on average more related to their cuckolders than expected by chance. Queller-Goodnight estimates of relatedness between males and their cuckolders are on average r = 0.038 but can range up to r = 0.64. This also increases the relatedness between males and the extra-pair offspring under their care. These intriguing results are consistent with the predictions of our mathematical model, which shows that elevated relatedness between paired males and their cuckolders can be adaptive for both parties when competition for fertilizations is strong.

CONCLUSIONS: Our results show how cuckoldry by relatives can offset males' direct fitness losses with inclusive fitness gains, which can be substantial in systems where males face almost certain paternity losses.

RevDate: 2020-01-13

Grodwohl JB (2019)

Animal Behavior, Population Biology and the Modern Synthesis (1955-1985).

Journal of the history of biology, 52(4):597-633.

This paper examines the history of animal behavior studies after the synthesis period. Three episodes are considered: the adoption of the theory of natural selection, the mathematization of ideas, and the spread of molecular methods in behavior studies. In these three episodes, students of behavior adopted practices and standards developed in population ecology and population genetics. While they borrowed tools and methods from these fields, they made distinct uses (inclusive fitness method, evolutionary theory of games, emphasis on individual selection) that set them relatively apart and led them to contribute, in their own way, to evolutionary theory. These episodes also highlight some limitations of "conjunction narratives" centered on the relation between a discipline and the modern synthesis. A trend in conjunction narratives is to interpret any development related to evolution in a discipline as an "extension," an "integration," or as a "delayed" synthesis. I here suggest that this can lead to underestimate discontinuities in the history of evolutionary biology.

RevDate: 2020-01-29

Patel M, Raymond B, Bonsall MB, et al (2019)

Crystal toxins and the volunteer's dilemma in bacteria.

Journal of evolutionary biology, 32(4):310-319.

The growth and virulence of the bacteria Bacillus thuringiensis depend on the production of Cry toxins, which are used to perforate the gut of its host. Successful invasion of the host relies on producing a threshold amount of toxin, after which there is no benefit from producing more toxin. Consequently, the production of Cry toxin appears to be a different type of social problem compared with the public goods scenarios that bacteria usually encounter. We show that selection for toxin production is a volunteer's dilemma. We make specific predictions that (a) selection for toxin production depends upon an interplay between the number of bacterial cells that each host ingests and the genetic relatedness between those cells; (b) cheats that do not produce toxin gain an advantage when at low frequencies, and at high bacterial density, allowing them to be maintained in a population alongside toxin-producing cells. More generally, our results emphasize the diversity of the social games that bacteria play.

RevDate: 2019-06-13
CmpDate: 2019-06-10

Barstow BA, Vice J, Bowman S, et al (2019)

Examining perceptions of existing and newly created accessibility symbols.

Disability and health journal, 12(2):180-186.

BACKGROUND: Symbols are used to convey messages in a clear, understandable manner, without the use of written language. The most widely recognized symbol used to denote access for persons with disabilities is the International Symbol of Access. This symbol has been criticized for its inadequate representation of disability diversity poorly representing universal design of space and products.

OBJECTIVE: This descriptive study explored individual comprehension and perceptions of nine existing and newly created accessibility pictograph symbols and identified one that represented universal access to fitness equipment.

METHODS: A survey was disseminated electronically and face-to-face to individuals, groups and organizations affiliated with inclusive fitness equipment, space and programming. Quantitative data was analyzed for descriptive statistics, rank order of symbols and group comparisons of rankings. Thematic analysis of open-ended question results revealed themes to enhance understanding of symbol rank order.

RESULTS: 981 participants completed the survey. Symbol four, shaped as a Venn diagram containing three icons representing individuals with varying ability levels, was ranked highest with no significant differences in group comparisons between participants with and without a disability and U.S. residents versus non-U.S. residents. 85.4% of participants demonstrated accurate comprehension of this symbol. Though symbol five had the same symbol rank median value, this symbol's distribution of scores was lower.

CONCLUSIONS: Participants accurately comprehended symbol four and it was identified as the highest ranked symbol representing universal access to fitness equipment. Because of symbol unfamiliarity, adoption will require education and consistency of use and placement.


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.

Electronic Scholarly Publishing
961 Red Tail Lane
Bellingham, WA 98226

E-mail: RJR8222 @

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 )