Evolution of non-kin cooperation:social assortment by cooperative phenotype in guppies

© 2019 The Authors. Cooperation among non-kin constitutes a conundrum for evolutionary biology. Theory suggests that non-kin cooperation can evolve if individuals differ consistently in their cooperative phenotypes and assort socially by these, such that cooperative individuals interact predominantly with one another. However, our knowledge of the role of cooperative phenotypes in the social structuring of real-world animal populations is minimal. In this study, we investigated cooperative phenotypes and their link to social structure in wild Trinidadian guppies (Poecilia reticulata). We first investigated whether wild guppies are repeatable in their individual levels of cooperativeness (i.e. have cooperative phenotypes) and found evidence for this in seven out of eight populations, a result which was mostly driven by females. We then examined the social network structure of one of these populations where the expected fitness impact of cooperative contexts is relatively high, and found assortment by cooperativeness, but not by genetic relatedness. By contrast, and in accordance with our expectations, we did not find assortment by cooperativeness in a population where the expected fitness impact of cooperative contexts is lower. Our results provide empirical support for current theory and suggest that assortment by cooperativeness is important for the evolution and persistence of non-kin cooperation in real-world populations

Data from: Cannibalism as an interacting phenotype: pre-cannibalistic aggression is influenced by social partners in the endangered Socorro isopod (Thermosphaeroma thermophilum)

Models for the evolution of cannibalism highlight the importance of asymmetries between individuals in initiating cannibalistic attacks. Studies may include measures of body size but typically group individuals into size/age classes or compare populations. Such broad comparisons may obscure the details of interactions that ultimately determine how socially contingent characteristics evolve. We propose that understanding cannibalism is facilitated by using an interacting phenotypes perspective that includes the influences of the phenotype of a social partner on the behaviour of a focal individual and focuses on variation in individual pairwise interactions. We investigated how relative body size, a composite trait between a focal individual and its social partner, and the sex of the partners influenced precannibalistic aggression in the endangered Socorro isopod, Thermosphaeroma thermophilum. We also investigated whether differences in mating interest among males and females influenced cannibalism in mixed sex pairs. We studied these questions in three populations that differ markedly in range of body size and opportunities for interactions among individuals. We found that relative body size influences the probability of and latency to attack. We observed differences in the likelihood of and latency to attack based on both an individual's sex and the sex of its partner but found no evidence of sexual conflict. The instigation of precannibalistic aggression in these isopods is therefore a property of both an individual and its social partner. Our results suggest that interacting phenotype models would be improved by incorporating a new conditional ψ, which describes the strength of a social partner's influence on focal behaviour

The evolution of cooperation: Interacting phenotypes among social partners

© 2017 by The University of Chicago. 0003-0147/2017/18906-56634$15.00. All rights reserved. Models of cooperation among nonkin suggest that social assortment is important for the evolution of cooperation. Theory predicts that interacting phenotypes, whereby an individual’s behavior depends on the behavior of its social partners, can drive such social assortment. We measured repeated indirect genetic effects (IGEs) during cooperative predator inspection in eight populations of Trinidadian guppies (Poecilia reticulata) that vary in their evolutionary history of predation. Four broad patterns emerged that were dependent on river, predation history, and sex: (i) current partner behavior had the largest effect on focal behavior, with fish from low-predation habitats responding more to their social partners than fish from high-predation habitats; (ii) different focal/partner behavior combinations can generate cooperation; (iii) some high-predation fish exhibited carryover effects across social partners; and (iv) high-predation fish were more risk averse. These results provide the first large-scale comparison of interacting phenotypes during cooperation across wild animal populations, highlighting the potential importance of IGEs in maintaining cooperation. Intriguingly, while focal fish responded strongly to current social partners, carryover effects between social partners suggest generalized reciprocity (in which one helps anyone if helped by someone) may contribute to the evolution of cooperation in some, but not all, populations of guppies

The influence of maternal effects on indirect benefits associated with polyandry

Despite numerous and diverse theoretical models for the indirect benefits of polyandry, empirical support is mixed. One reason for the difficulty in detecting indirect benefits of polyandry may be that these are subtle and are mediated by environmental effects, such as maternal effects. Maternal effects may be especially important if females allocate resources to their offspring depending on the characteristics of their mating partners. We test this hypothesis in the burying beetle Nicrophorus vespilloides, a species that provides extensive and direct parental care to offspring. We used a fully factorial design and mated females to one, two, three, four or five different males and manipulated conditions so that their offspring received reduced (12 h) or full (ca 72 h) maternal care. We found that average offspring fitness increased with full maternal care but there was no significant effect of polyandry or the interaction between the duration of maternal care and the level of polyandry on offspring fitness. Thus, although polyandry could provide a mechanism for biasing paternity towards high quality or compatible males, and variation in parental care matters, we found no evidence that female N. vespilloides gain indirect benefits by using parental care to bias the allocation of resources under different mating conditions

Exposure to the ultraviolet filter benzophenone-3 (BP3) interferes with social behaviour in male Siamese fighting fish

© 2019 The Association for the Study of Animal Behaviour Oxybenzones like benzophenone-3 (BP3) are ultraviolet (UV) filters widely used in personal care products such as sunscreens. BP3 is currently receiving a great deal of attention because many of its properties, including high water solubility and potential to bioaccumulate, enable it to have damaging effects on aquatic ecosystems. One of these effects, the induction of coral bleaching, has led Hawaii to ban all sunscreens containing BP3. BP3 also appears to have endocrine-disrupting properties and has been found to affect animal physiology. However, behavioural consequences of BP3 exposure have yet to be thoroughly characterized. In the present study, we investigated the effects of BP3 on boldness, courtship and aggression in male Siamese fighting fish, Betta splendens, as little is known about the effects that BP3 has on fish social behaviour. To accomplish this, we assigned males to a treatment group (control, low, medium or high BP3 concentration) and completed individual (empty tank, novel environment and shoal) and social (courtship and aggression) behavioural assays before and after a 28-day exposure period. BP3 influenced the expression of social behaviours, with individual boldness generally unaffected. Changes in shoaling occurred regardless of BP3 concentration, while BP3-associated decreases in courtship and aggression were concentration dependent. Abnormal social behaviour may impede successful mating and alter territorial dynamics, with potentially heightened effects in species already experiencing other anthropogenic stressors

Exposure to the ultraviolet filter benzophenone-3 (BP3) interferes with social behaviour in male Siamese fighting fish

© 2019 The Association for the Study of Animal Behaviour Oxybenzones like benzophenone-3 (BP3) are ultraviolet (UV) filters widely used in personal care products such as sunscreens. BP3 is currently receiving a great deal of attention because many of its properties, including high water solubility and potential to bioaccumulate, enable it to have damaging effects on aquatic ecosystems. One of these effects, the induction of coral bleaching, has led Hawaii to ban all sunscreens containing BP3. BP3 also appears to have endocrine-disrupting properties and has been found to affect animal physiology. However, behavioural consequences of BP3 exposure have yet to be thoroughly characterized. In the present study, we investigated the effects of BP3 on boldness, courtship and aggression in male Siamese fighting fish, Betta splendens, as little is known about the effects that BP3 has on fish social behaviour. To accomplish this, we assigned males to a treatment group (control, low, medium or high BP3 concentration) and completed individual (empty tank, novel environment and shoal) and social (courtship and aggression) behavioural assays before and after a 28-day exposure period. BP3 influenced the expression of social behaviours, with individual boldness generally unaffected. Changes in shoaling occurred regardless of BP3 concentration, while BP3-associated decreases in courtship and aggression were concentration dependent. Abnormal social behaviour may impede successful mating and alter territorial dynamics, with potentially heightened effects in species already experiencing other anthropogenic stressors

Body size and aggressive attack latency data for Socorro isopods

Data collected in the field in May 2009 in Socorro, NM. Data archived in Excel, JMP 9.0.2 was used to create principle component measure of body size and transform data