1
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Ross CT, McElreath R, Redhead D. Modelling animal network data in R using STRAND. J Anim Ecol 2024; 93:254-266. [PMID: 37936514 DOI: 10.1111/1365-2656.14021] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/27/2023] [Indexed: 11/09/2023]
Abstract
There have been recent calls for wider application of generative modelling approaches in applied social network analysis. At present, however, it remains difficult for typical end users-for example, field researchers-to implement generative network models, as there is a dearth of openly available software packages that make application of such models as simple as other, permutation-based approaches. Here, we outline the STRAND R package, which provides a suite of generative models for Bayesian analysis of animal social network data that can be implemented using simple, base R syntax. To facilitate ease of use, we provide a tutorial demonstrating how STRAND can be used to model proportion, count or binary network data using stochastic block models, social relation models or a combination of the two modelling frameworks. STRAND facilitates the application of generative network models to a broad range of data found in the animal social networks literature.
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Affiliation(s)
- Cody T Ross
- Department of Human Behavior, Ecology, and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Richard McElreath
- Department of Human Behavior, Ecology, and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Daniel Redhead
- Department of Human Behavior, Ecology, and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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2
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Kings M, Arbon JJ, McIvor GE, Whitaker M, Radford AN, Lerner J, Thornton A. Wild jackdaws can selectively adjust their social associations while preserving valuable long-term relationships. Nat Commun 2023; 14:5103. [PMID: 37696804 PMCID: PMC10495349 DOI: 10.1038/s41467-023-40808-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 08/09/2023] [Indexed: 09/13/2023] Open
Abstract
Influential theories of the evolution of cognition and cooperation posit that tracking information about others allows individuals to adjust their social associations strategically, re-shaping social networks to favour connections between compatible partners. Crucially, to our knowledge, this has yet to be tested experimentally in natural populations, where the need to maintain long-term, fitness-enhancing relationships may limit social plasticity. Using a social-network-manipulation experiment, we show that wild jackdaws (Corvus monedula) learned to favour social associations with compatible group members (individuals that provided greater returns from social foraging interactions), but resultant change in network structure was constrained by the preservation of valuable pre-existing relationships. Our findings provide insights into the cognitive basis of social plasticity and the interplay between individual decision-making and social-network structure.
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Affiliation(s)
- Michael Kings
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Treliever Road, Penryn, TR10 9FE, UK.
| | - Josh J Arbon
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Treliever Road, Penryn, TR10 9FE, UK.
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK.
| | - Guillam E McIvor
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Treliever Road, Penryn, TR10 9FE, UK
| | - Martin Whitaker
- technologywithin, Chevron Business Park, Limekiln Lane, Holbury, Southampton, SO45 2QL, UK
| | - Andrew N Radford
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Jürgen Lerner
- Department of Computer and Information Science, University of Konstanz, 78457, Konstanz, Germany
- HumTec Institute, RWTH Aachen University, 52062, Aachen, Germany
| | - Alex Thornton
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Treliever Road, Penryn, TR10 9FE, UK.
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3
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Padget RFB, Fawcett TW, Darden SK. Guppies in large groups cooperate more frequently in an experimental test of the group size paradox. Proc Biol Sci 2023; 290:20230790. [PMID: 37434522 PMCID: PMC10336388 DOI: 10.1098/rspb.2023.0790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 06/16/2023] [Indexed: 07/13/2023] Open
Abstract
The volunteer's dilemma, in which a single individual is required to produce a public good, predicts that individuals in larger groups will cooperate less frequently. Mechanistically, this could result from trade-offs between costs associated with volunteering and costs incurred if the public good is not produced (nobody volunteers). During predator inspection, one major contributor to the cost of volunteering is likely increased probability of predation; however, a predator also poses a risk to all individuals if nobody inspects. We tested the prediction that guppies in larger groups will inspect a predator less than those in smaller groups. We also predicted that individuals in larger groups would perceive less threat from the predator stimulus because of the protective benefits of larger groups (e.g. dilution). Contrary to prediction, we found that individuals in large groups inspected more frequently than those in smaller groups, but (as predicted) spent less time in refuges. There was evidence that individuals in intermediate-sized groups made fewest inspections and spent most time in refuges, suggesting that any link between group size, risk and cooperation is not driven by simple dilution. Extensions of theoretical models that capture these dynamics will likely be broadly applicable to risky cooperative behaviour.
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Affiliation(s)
- Rebecca F. B. Padget
- Centre for Research in Animal Behaviour, Department of Psychology, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Tim W. Fawcett
- Centre for Research in Animal Behaviour, Department of Psychology, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Safi K. Darden
- Centre for Research in Animal Behaviour, Department of Psychology, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
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4
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Gokcekus S, Firth JA, Regan C, Cole EF, Sheldon BC, Albery GF. Social familiarity and spatially variable environments independently determine reproductive fitness in a wild bird. Am Nat 2023; 201:813-824. [DOI: 10.1086/724382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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5
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Brain monoaminergic activity during predator inspection in female Trinidadian guppies (Poecilia reticulata). Behav Brain Res 2023; 436:114088. [DOI: 10.1016/j.bbr.2022.114088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 08/29/2022] [Accepted: 08/29/2022] [Indexed: 11/24/2022]
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6
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Glowacki L, McDermott R. Key individuals catalyse intergroup violence. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210141. [PMID: 35369758 PMCID: PMC8977664 DOI: 10.1098/rstb.2021.0141] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/20/2021] [Indexed: 01/19/2023] Open
Abstract
Intergroup violence is challenging to understand: why do individuals cooperate to harm members of other groups when they themselves may be killed or injured? Despite progress in understanding the evolutionary and proximate mechanisms that underlie violence, we still have little insight into the processes that lead to the emergence of coalitionary aggression. We argue that an overlooked component is the presence of individuals who have a crucial role in initiating violence. In instigating intergroup violence, these key individuals may expect to face lower costs, receive greater benefits, or garner benefits that have a greater value to them than others. Alternatively, key individuals may be motivated by individual traits such as increased boldness, propensity for aggression or exploratory behaviour. Key individuals catalyse the emergence of coalitionary violence through one of several processes including altering the costs and benefits that accrue to others, paying a greater share of the startup costs, signalling privileged knowledge, or providing coordination, among other factors. Here we integrate diverse lines of empirical research from humans and non-human animals demonstrating that inter-individual variation is an important factor in the emergence of intergroup violence. Focusing on the role of key individuals provides new insights into how and why violence emerges. This article is part of the theme issue 'Intergroup conflict across taxa'.
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Affiliation(s)
| | - Rose McDermott
- Political Science, Brown University, Providence, RI, USA
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7
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Martin JS, Jaeggi AV. Social animal models for quantifying plasticity, assortment, and selection on interacting phenotypes. J Evol Biol 2022; 35:520-538. [PMID: 34233047 PMCID: PMC9292565 DOI: 10.1111/jeb.13900] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 05/14/2021] [Accepted: 06/24/2021] [Indexed: 11/29/2022]
Abstract
Both assortment and plasticity can facilitate social evolution, as each may generate heritable associations between the phenotypes and fitness of individuals and their social partners. However, it currently remains difficult to empirically disentangle these distinct mechanisms in the wild, particularly for complex and environmentally responsive phenotypes subject to measurement error. To address this challenge, we extend the widely used animal model to facilitate unbiased estimation of plasticity, assortment and selection on social traits, for both phenotypic and quantitative genetic (QG) analysis. Our social animal models (SAMs) estimate key evolutionary parameters for the latent reaction norms underlying repeatable patterns of phenotypic interaction across social environments. As a consequence of this approach, SAMs avoid inferential biases caused by various forms of measurement error in the raw phenotypic associations between social partners. We conducted a simulation study to demonstrate the application of SAMs and investigate their performance for both phenotypic and QG analyses. With sufficient repeated measurements, we found desirably high power, low bias and low uncertainty across model parameters using modest sample and effect sizes, leading to robust predictions of selection and adaptation. Our results suggest that SAMs will readily enhance social evolutionary research on a variety of phenotypes in the wild. We provide detailed coding tutorials and worked examples for implementing SAMs in the Stan statistical programming language.
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Affiliation(s)
- Jordan S. Martin
- Human Ecology GroupInstitute of Evolutionary MedicineUniversity of ZurichZurichSwitzerland
| | - Adrian V. Jaeggi
- Human Ecology GroupInstitute of Evolutionary MedicineUniversity of ZurichZurichSwitzerland
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8
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Cook PA, Baker OM, Costello RA, Formica VA, Brodie ED. Group composition of individual personalities alters social network structure in experimental populations of forked fungus beetles. Biol Lett 2022; 18:20210509. [PMID: 35291883 PMCID: PMC8923822 DOI: 10.1098/rsbl.2021.0509] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 02/24/2022] [Indexed: 01/02/2023] Open
Abstract
Social network structure is a critical group character that mediates the flow of information, pathogens and resources among individuals in a population, yet little is known about what shapes social structures. In this study, we experimentally tested whether social network structure depends on the personalities of individual group members. Replicate groups of forked fungus beetles (Bolitotherus cornutus) were engineered to include only members previously assessed as either more social or less social. We found that individuals expressed consistent personalities across social contexts, exhibiting repeatable numbers of interactions and numbers of partners. Groups composed of more social individuals formed networks with higher interaction rates, higher tie density, higher global clustering and shorter average shortest paths than those composed of less social individuals. We highlight group composition of personalities as a source of variance in group traits and a potential mechanism by which networks could evolve.
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Affiliation(s)
- Phoebe A. Cook
- Department of Biology and Mountain Lake Biological Station, University of Virginia, Charlottesville, VA 22904, USA
| | - Olivia M. Baker
- Department of Biology and Mountain Lake Biological Station, University of Virginia, Charlottesville, VA 22904, USA
| | - Robin A. Costello
- Department of Biology and Mountain Lake Biological Station, University of Virginia, Charlottesville, VA 22904, USA
| | | | - Edmund D. Brodie
- Department of Biology and Mountain Lake Biological Station, University of Virginia, Charlottesville, VA 22904, USA
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9
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Ostwald MM, Haney BR, Fewell JH. Ecological Drivers of Non-kin Cooperation in the Hymenoptera. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.768392] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Despite the prominence of kin selection as a framework for understanding the evolution of sociality, many animal groups are comprised of unrelated individuals. These non-kin systems provide valuable models that can illuminate drivers of social evolution beyond indirect fitness benefits. Within the Hymenoptera, whose highly related eusocial groups have long been cornerstones of kin selection theory, groups may form even when indirect fitness benefits for helpers are low or absent. These non-kin groups are widespread and abundant, yet have received relatively little attention. We review the diversity and organization of non-kin sociality across the Hymenoptera, particularly among the communal bees and polygynous ants and wasps. Further, we discuss common drivers of sociality across these groups, with a particular focus on ecological factors. Ecological contexts that favor non-kin sociality include those dominated by resource scarcity or competition, climatic stressors, predation and parasitism, and/or physiological constraints associated with reproduction and resource exploitation. Finally, we situate Hymenopteran non-kin sociality within a broader biological context by extending insights from these systems across diverse taxa, especially the social vertebrates. Non-kin social groups thus provide unique demonstrations of the importance of ecological factors in mediating the evolutionary transition from solitary to group living.
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10
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Dimitriadou S, Santos EM, Croft DP, van Aerle R, Ramnarine IW, Filby AL, Darden SK. Social partner cooperativeness influences brain oxytocin transcription in Trinidadian guppies (Poecilia reticulata). Behav Brain Res 2021; 423:113643. [PMID: 34757109 DOI: 10.1016/j.bbr.2021.113643] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 10/01/2021] [Accepted: 10/25/2021] [Indexed: 11/02/2022]
Abstract
For non-kin cooperation to be maintained, individuals need to respond adaptively to the cooperative behaviour of their social partners. Currently, however, little is known about the biological responses of individuals to experiencing cooperation. Here, we quantify the neuroregulatory response of Trinidadian guppies (Poecilia reticulata) experiencing cooperation or defection by examining the transcriptional response of the oxytocin gene (oxt; also known as isotocin), which has been implicated in cooperative decision-making. We exposed wild-caught females to social environments where partners either cooperated or defected during predator inspection, or to a control (non-predator inspection) context, and quantified the relative transcription of the oxt gene. We tested an experimental group, originating from a site where individuals are under high predation threat and have previous experience of large aquatic predators (HP), and a control group, where individuals are under low predation threat and naïve to large aquatic predators (LP). LP, but not HP, fish showed different behavioural responses to the behaviour of their social environment, cooperating with cooperative partners and defecting when paired with defecting ones. In HP, but not LP, fish brain mid-section oxt relative transcription varied depending on social partner behaviour. HP fish experiencing cooperation during predator inspection had lower oxt transcription than those experiencing defection. This effect was not present in the control population or in the control context, where the behaviour of social partners did not affect oxt transcription. Our findings provide insight into the neuromodulation underpinning behavioural responses to social experiences, and ultimately to the proximate mechanisms underlying social decision-making.
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Affiliation(s)
- Sylvia Dimitriadou
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, UK.
| | - Eduarda M Santos
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK; Sustainable Aquaculture Futures, Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Darren P Croft
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, UK
| | - Ronny van Aerle
- Sustainable Aquaculture Futures, Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK; International Centre of Excellence for Aquatic Animal Health, Cefas Weymouth Laboratory, Weymouth, UK
| | - Indar W Ramnarine
- Department of Life Sciences, University of West Indies, St. Augustine, Trinidad and Tobago
| | - Amy L Filby
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Safi K Darden
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, UK
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11
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Janecka MJ, Rovenolt F, Stephenson JF. How does host social behavior drive parasite non-selective evolution from the within-host to the landscape-scale? Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03089-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Correa LA, León C, Ramírez-Estrada J, Ly-Prieto Á, Abades S, Hayes LD, Soto-Gamboa M, Ebensperger LA. One for all and all for one: phenotype assortment and reproductive success in masculinized females. Behav Ecol 2021. [DOI: 10.1093/beheco/arab093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Abstract
Homophily by morphological and behavioral traits has been described in several species of vertebrates, but its functional consequences remain poorly studied. Homophily by plurally breeding females may improve direct fitness by enhancing reproductive success. Female mammals may exhibit phenotypical masculinization due to exposure to androgens during early development, a condition that is associated with maternal performance during subsequent breeding. Our goal was to assess whether female composition (in terms of masculinization) of plurally breeding groups influences female fitness in a natural population of degus (Octodon degus). We assessed if plurally breeding female degus assort themselves by anogenital distance (AGD), an accurate measure of masculinization level. We also quantified if homophily by AGD phenotype affects female reproductive success and the reproductive output of the group. Plurally breeding groups typically included similarly masculinized (i.e., long AGD) females or similarly feminized (short AGD) females, indicating a strong degree of homophily. Females weaned more offspring in plurally breeding groups with more masculinized females. Additionally, standardized variance in the number of offspring weaned decreased in plurally breeding groups with mostly masculinized females, indicating greater reproductive equality in these groups. We conclude that female degus organize into homophilic social groups of similar AGD, and that social groups of masculinized females exhibit a higher reproductive success.
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Affiliation(s)
- Loreto A Correa
- Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Camino la Pirámide, Huechuraba, Santiago, Chile
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla, Avenida Bernardo O’Higgins, Santiago, Chile
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla, Avenida Bernardo O’Higgins, Santiago, Chile
| | - Juan Ramírez-Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla, Avenida Bernardo O’Higgins, Santiago, Chile
| | - Álvaro Ly-Prieto
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla, Avenida Bernardo O’Higgins, Santiago, Chile
| | - Sebastián Abades
- GEMA Center for Genomics, Ecology & Environment, Faculty of Interdisciplinary Studies, Universidad Mayor, Camino La Pirámide, Huechuraba, Santiago, Chile
| | - Loren D Hayes
- Department of Biology, Geology and Environmental Sciences, University of Tennessee at Chattanooga, Chattanooga, TN, USA
| | - Mauricio Soto-Gamboa
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla, Isla Teja s/n, Valdivia, Chile
| | - Luis A Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Casilla, Avenida Bernardo O’Higgins, Santiago, Chile
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13
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Recognising the key role of individual recognition in social networks. Trends Ecol Evol 2021; 36:1024-1035. [PMID: 34256987 DOI: 10.1016/j.tree.2021.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 11/21/2022]
Abstract
Many aspects of sociality rely on individuals recognising one another. Understanding how, when, and if individuals recognise others can yield insights into the foundations of social relationships and behaviours. Through synthesising individual recognition research in different sensory and social domains, and doing so across various related social contexts, we propose that a social network perspective can help to uncover how individual recognition may vary across different settings, species, and populations. Specifically, combining individual recognition with social networks has unrecognised potential for determining the level and relative importance of individual recognition complexity. This will provide insights not only on the ecology and evolution of individual recognition itself, but also on social structure, social transmission, and social interactions such as cooperation.
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14
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Gokcekus S, Cole EF, Sheldon BC, Firth JA. Exploring the causes and consequences of cooperative behaviour in wild animal populations using a social network approach. Biol Rev Camb Philos Soc 2021; 96:2355-2372. [DOI: 10.1111/brv.12757] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 12/26/2022]
Affiliation(s)
- Samin Gokcekus
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
| | - Ella F. Cole
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
| | - Ben C. Sheldon
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
| | - Josh A. Firth
- Department of Zoology, Edward Grey Institute University of Oxford 11a Mansfield Road Oxford OX1 3SZ U.K
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15
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Fishman MA. Cooperation, involuntary defection, and Polymorphic Evolutionary Games. Biosystems 2021; 206:104428. [PMID: 33894287 DOI: 10.1016/j.biosystems.2021.104428] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/06/2021] [Accepted: 04/06/2021] [Indexed: 01/03/2023]
Abstract
The subject of involuntary defection in the context of cycles of interaction approach to direct reciprocal cooperation was introduced some time ago (J. Theor. Biol., 242: 873-879). Current work is motivated by the subsequent accumulation of empirical evidence and the advances in the methodology of evolutionary games. In recent decades it become clear that individuals in many animal species vary consistently in their behavioral responses to specific challenges-animal personality. Moreover, these differences have a hereditary component. Finally, investigations into the effects of neuropeptides on behavior suggest that the variations in animal personalities involve polymorphisms based on non-Mendelian heritability within the neuropeptide signaling systems. The last observation suggests that animal personalities can be productively analyzed via Polymorphic Evolutionary Games, which allow us to add genetic model(s) to standard (phenotypic) evolutionary games. Such an analysis of reciprocal cooperation is the subject of the current paper. The results indicate that there is a marked difference between models that assume Mendelian vs. non-Mendelian inheritance of the pertinent traits. Monomorphic and polymorphic-Mendelian models predict pure-strategy (single phenotype) ESS, whereas the non-Mendelian genetic model predicts a mixed strategy ESS exhibiting all three phenotypes.
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16
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Li C, Lessard S. The effect of the opting-out strategy on conditions for selection to favor the evolution of cooperation in a finite population. J Theor Biol 2020; 510:110543. [PMID: 33221279 DOI: 10.1016/j.jtbi.2020.110543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 11/16/2022]
Abstract
We consider a Prisoner's Dilemma (PD) that is repeated with some probability 1-ρ only between cooperators as a result of an opting-out strategy adopted by all individuals. The population is made of N pairs of individuals and is updated at every time step by a birth-death event according to a Moran model. Assuming an intensity of selection of order 1/N and taking 2N2 birth-death events as unit of time, a diffusion approximation exhibiting two time scales, a fast one for pair frequencies and a slow one for cooperation (C) and defection (D) frequencies, is ascertained in the limit of a large population size. This diffusion approximation is applied to an additive PD game, cooperation by an individual incurring a cost c to the individual but providing a benefit b to the opponent. This is used to obtain the probability of ultimate fixation of C introduced as a single mutant in an all D population under selection, which can be compared to the probability under neutrality, 1/(2N), as well as the corresponding probability for a single D introduced in an all C population under selection. This gives conditions for cooperation to be favored by selection. We show that these conditions are satisfied when the benefit-to-cost ratio, b/c, exceeds some increasing function of ρ that is approximately given by (1+ρ)/(1-ρ). This condition is more stringent, however, than the condition for tit-for-tat (TFT) to be favored against always-defect (AllD) in the absence of opting-out.
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Affiliation(s)
- Cong Li
- Département de mathématiques et de statistique, Université de Montréal, Montréal, Québec, Canada
| | - Sabin Lessard
- Département de mathématiques et de statistique, Université de Montréal, Montréal, Québec, Canada.
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17
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Darden SK, James R, Cave JM, Brask JB, Croft DP. Trinidadian guppies use a social heuristic that can support cooperation among non-kin. Proc Biol Sci 2020; 287:20200487. [PMID: 32900316 DOI: 10.1098/rspb.2020.0487] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Cooperation among non-kin is well documented in humans and widespread in non-human animals, but explaining the occurrence of cooperation in the absence of inclusive fitness benefits has proven a significant challenge. Current theoretical explanations converge on a single point: cooperators can prevail when they cluster in social space. However, we know very little about the real-world mechanisms that drive such clustering, particularly in systems where cognitive limitations make it unlikely that mechanisms such as score keeping and reputation are at play. Here, we show that Trinidadian guppies (Poecilia reticulata) use a 'walk away' strategy, a simple social heuristic by which assortment by cooperativeness can come about among mobile agents. Guppies cooperate during predator inspection and we found that when experiencing defection in this context, individuals prefer to move to a new social environment, despite having no prior information about this new social group. Our results provide evidence in non-human animals that individuals use a simple social partner updating strategy in response to defection, supporting theoretical work applying heuristics to understanding the proximate mechanisms underpinning the evolution of cooperation among non-kin.
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Affiliation(s)
- Safi K Darden
- Centre for Research in Animal Behaviour, Department of Psychology, College of Life and Environmental Sciences, University of Exeter, UK
| | - Richard James
- Department of Physics and Centre for Networks and Collective Behaviour, University of Bath, Bath, UK
| | - James M Cave
- Department of Physics and Centre for Networks and Collective Behaviour, University of Bath, Bath, UK
| | - Josefine Bohr Brask
- Centre for Research in Animal Behaviour, Department of Psychology, College of Life and Environmental Sciences, University of Exeter, UK
| | - Darren P Croft
- Centre for Research in Animal Behaviour, Department of Psychology, College of Life and Environmental Sciences, University of Exeter, UK
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Dimitriadou S, Croft DP, Darden SK. Divergence in social traits in Trinidadian guppies selectively bred for high and low leadership in a cooperative context. Sci Rep 2019; 9:17194. [PMID: 31748621 PMCID: PMC6868185 DOI: 10.1038/s41598-019-53748-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 11/05/2019] [Indexed: 11/12/2022] Open
Abstract
In many animal species, individuals with certain morphological, physiological, or behavioural traits may have a disproportionately large role in determining group behaviour. While most empirical studies of leadership have focused on behaviour of individuals exploring new environments or foraging, little is known about leading behaviour in other ecological contexts. Here, we use a selective breeding design in the Trinidadian guppy (Poecilia reticulata) to quantify the heritability of leadership in a cooperative context, and determine the behavioural traits associated with it. Firstly we found that phenotypic selection for high and low leadership (HL and LL, respectively) over three filial generations resulted in pronounced differences in leadership tendency with a moderate degree of heritability. In our assay of other social traits, LL males were more aggressive and sampled their social environment less than HL males, but HL and LL females did not differ in either aggressiveness or sociability. Traits such as boldness and exploratory tendency did not diverge between the two lines. Leading behaviour was thus associated with social traits in males, but not females; suggesting that there may be sex-specific mechanisms driving the emergence of leadership in this context. We discuss our findings in the context of the evolution of cooperation.
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Affiliation(s)
- S Dimitriadou
- Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter, EX4 4QG, UK.
| | - D P Croft
- Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter, EX4 4QG, UK
| | - S K Darden
- Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Washington Singer Laboratories, Perry Road, Exeter, EX4 4QG, UK
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Woodford P. Evaluating inclusive fitness. ROYAL SOCIETY OPEN SCIENCE 2019; 6:190644. [PMID: 31312507 PMCID: PMC6599781 DOI: 10.1098/rsos.190644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 05/29/2019] [Indexed: 06/10/2023]
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