1
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Simpson S, Briffa M. Sea anemones ( Actinia equina) show consistent individual differences in boldness and thoroughness but lack a behavioural syndrome. Proc Biol Sci 2024; 291:20241345. [PMID: 39013424 PMCID: PMC11251758 DOI: 10.1098/rspb.2024.1345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 06/25/2024] [Accepted: 06/25/2024] [Indexed: 07/18/2024] Open
Abstract
Behavioural syndromes are suites of behaviours that corelate between-individuals but the same behaviours may also show within-individual correlations owing to state dependency or trade-offs. Therefore, overall phenotypic behavioural correlations must be separated into their between- and within-individual components. We investigate how startle response duration (an index of boldness) and time taken to reject an inert item (an index of investigation thoroughness) covary in beadlet sea anemones, Actinia equina. Anemones took longer to reject a more complex item compared to a simpler one, validating this measure of investigation thoroughness. We then quantified between- and within-individual correlations using a Bayesian analysis and an alternative frequentist analysis, which returned the same results. Startle responses decreased with anemone size while thoroughness decreased across repeated observations, indicative of simple learning. For each behaviour, repeatability was significant but relatively low and there was no behavioural syndrome. Rather, the two behaviours showed a negative within-individual correlation in most individuals. Thus, boldness and thoroughness are unlikely to be under correlative selection, and they may instead be expressed independently, in line with the general pattern that cross-contextual behavioural syndromes are comparatively rare. It now appears that this pattern may extend broadly across animal diversity.
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Affiliation(s)
- Samantha Simpson
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, PlymouthPL4 8AA, UK
| | - Mark Briffa
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, PlymouthPL4 8AA, UK
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2
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McNamara JM, Dall SRX, Houston AI, Leimar O. The evolutionary consequences of learning under competition. Proc Biol Sci 2024; 291:20241141. [PMID: 39110908 PMCID: PMC11305653 DOI: 10.1098/rspb.2024.1141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 06/17/2024] [Accepted: 06/17/2024] [Indexed: 08/10/2024] Open
Abstract
Learning is a taxonomically widespread process by which animals change their behavioural responses to stimuli as a result of experience. In this way, it plays a crucial role in the development of individual behaviour and underpins substantial phenotypic variation within populations. Nevertheless, the impact of learning in social contexts on evolutionary change is not well understood. Here, we develop game theoretical models of competition for resources in small groups (e.g. producer-scrounger and hawk-dove games) in which actions are controlled by reinforcement learning and show that biases in the subjective valuation of different actions readily evolve. Moreover, in many cases, the convergence stable levels of bias exist at fitness minima and therefore lead to disruptive selection on learning rules and, potentially, to the evolution of genetic polymorphisms. Thus, we show how reinforcement learning in social contexts can be a driver of evolutionary diversification. In addition, we consider the evolution of ability in our games, showing that learning can also drive disruptive selection on the ability to perform a task.
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Affiliation(s)
- John M. McNamara
- School of Mathematics, University of Bristol, BristolBS8 1UG, UK
| | - Sasha R. X. Dall
- Centre for Ecology and Conservation, University of Exeter, ExeterTR10 9FE, UK
| | | | - Olof Leimar
- Department of Zoology, Stockholm University, 10691 Stockholm, Sweden
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3
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Yang Y, Axelrod CJ, Grant E, Earl SR, Urquhart EM, Talbert K, Johnson LE, Walker Z, Hsiao K, Stone I, Carlson BA, López-Sepulcre A, Gordon SP. Evolutionary divergence of developmental plasticity and learning of mating tactics in Trinidadian guppies. J Anim Ecol 2023. [PMID: 38156548 DOI: 10.1111/1365-2656.14043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 11/30/2023] [Indexed: 12/30/2023]
Abstract
Behavioural plasticity is a major driver in the early stages of adaptation, but its effects in mediating evolution remain elusive because behavioural plasticity itself can evolve. In this study, we investigated how male Trinidadian guppies (Poecilia reticulata) adapted to different predation regimes diverged in behavioural plasticity of their mating tactic. We reared F2 juveniles of high- or low-predation population origins with different combinations of social and predator cues and assayed their mating behaviour upon sexual maturity. High-predation males learned their mating tactic from conspecific adults as juveniles, while low-predation males did not. High-predation males increased courtship when exposed to chemical predator cues during development; low-predation males decreased courtship in response to immediate chemical predator cues, but only when they were not exposed to such cues during development. Behavioural changes induced by predator cues were associated with developmental plasticity in brain morphology, but changes acquired through social learning were not. We thus show that guppy populations diverged in their response to social and ecological cues during development, and correlational evidence suggests that different cues can shape the same behaviour via different neural mechanisms. Our study demonstrates that behavioural plasticity, both environmentally induced and socially learnt, evolves rapidly and shapes adaptation when organisms colonize ecologically divergent habitats.
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Affiliation(s)
- Yusan Yang
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Integrative Biology, University of South Florida, Tampa, Florida, USA
| | - Caleb J Axelrod
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
| | - Elly Grant
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Shayna R Earl
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Biology, University of Louisville, Louisville, Kentucky, USA
| | - Ellen M Urquhart
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Katie Talbert
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
| | - Lauren E Johnson
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Zakiya Walker
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Kyle Hsiao
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Isabel Stone
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Bruce A Carlson
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Andrés López-Sepulcre
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
| | - Swanne P Gordon
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Ecology and Evolution, Cornell University, Ithaca, New York, USA
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4
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Arehart E, Adler FR. A minimal model of learning: quantifying the cost and benefit of learning in changing environments. Proc Biol Sci 2023; 290:20231084. [PMID: 37644832 PMCID: PMC10465976 DOI: 10.1098/rspb.2023.1084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 07/28/2023] [Indexed: 08/31/2023] Open
Abstract
Many organisms have the ability to learn, but the costs and benefits of learning are difficult to quantify. We construct a minimal mathematical model of learning in which a forager attempts to maximize the amount of resources (food) it collects in a changing environment. Our model has two learning parameters: α, corresponding to the duration of the forager's memory, and [Formula: see text], corresponding to how much the forager explores the environment to learn more about it. We analyse the effect of different regimes of environmental change on the optimal memory and exploration parameters [Formula: see text]. By comparing the fitness outcomes from learning foragers to the outcomes from foragers following fixed strategies, we explicitly quantify the fitness benefit (or cost) of learning as a function of environmental change. We find that in many environments, the marginal benefit of learning is surprisingly small. In every environment, it is possible to implement learning in such a way that performance is as bad or worse than following a fixed strategy. In some environments, even the best implementations of our minimal model of learning perform worse than the best fixed strategy. Finally, we find that variance in resource values negatively biases foragers' estimates for those values, potentially explaining experimental results showing that animals prefer less variable resources.
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Affiliation(s)
- Emerson Arehart
- Department of Biology, University of Pennsylvania, 433 S University Ave, Philadelphia, PA 19104, USA
| | - Frederick R. Adler
- Department of Mathematics and School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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5
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De Lisle SP, Rowe L. Condition dependence and the paradox of missing plasticity costs. Evol Lett 2023; 7:67-78. [PMID: 37033877 PMCID: PMC10078974 DOI: 10.1093/evlett/qrad009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 02/10/2023] [Accepted: 03/02/2023] [Indexed: 03/29/2023] Open
Abstract
AbstractPhenotypic plasticity plays a key role in adaptation to changing environments. However, plasticity is neither perfect nor ubiquitous, implying that fitness costs may limit the evolution of phenotypic plasticity in nature. The measurement of such costs of plasticity has proved elusive; decades of experiments show that fitness costs of plasticity are often weak or nonexistent. Here, we show that this paradox could potentially be explained by condition dependence. We develop two models differing in their assumptions about how condition dependence arises; both models show that variation in condition can readily mask costs of plasticity even when such costs are substantial. This can be shown simply in a model where plasticity itself evolves condition dependence, which would be expected if costly. Yet similar effects emerge from an alternative model where trait expression itself is condition-dependent. In this more complex model, the average condition in each environment and genetic covariance in condition across environments both determine when costs of plasticity can be revealed. Analogous to the paradox of missing trade-offs between life history traits, our models show that variation in condition can mask costs of plasticity even when costs exist, and suggest this conclusion may be robust to the details of how condition affects trait expression. Our models suggest that condition dependence can also account for the often-observed pattern of elevated plasticity costs inferred in stressful environments, the maintenance of genetic variance in plasticity, and provides insight into experimental and biological scenarios ideal for revealing a cost of phenotypic plasticity.
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Affiliation(s)
- Stephen P De Lisle
- Corresponding author: Department of Environmental and Life Science, Karlstad University, Universitetsgatan 2, Karlstad 651 88, Sweden.
| | - Locke Rowe
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
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de Groot C, Wijnhorst RE, Ratz T, Murray M, Araya-Ajoy YG, Wright J, Dingemanse NJ. The importance of distinguishing individual differences in 'social impact' versus 'social responsiveness' when quantifying indirect genetic effects on the evolution of social plasticity. Neurosci Biobehav Rev 2023; 144:104996. [PMID: 36526032 DOI: 10.1016/j.neubiorev.2022.104996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 12/05/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022]
Abstract
Social evolution and the dynamics of social interactions have previously been studied under the frameworks of quantitative genetics and behavioural ecology. In quantitative genetics, indirect genetic effects of social partners on the socially plastic phenotypes of focal individuals typically lack crucial detail already included in treatments of social plasticity in behavioural ecology. Specifically, whilst focal individuals (e.g. receivers) may show variation in their 'responsiveness' to the social environment, individual social partners (e.g. signallers) may have a differential 'impact' on focal phenotypes. Here we propose an integrative framework, that highlights the distinction between responsiveness versus impact in indirect genetic effects for a range of behavioural traits. We describe impact and responsiveness using a reaction norm approach and provide statistical models for the assessment of these effects of focal and social partner identity in different types of social interactions. By providing such a framework, we hope to stimulate future quantitative research investigating the causes and consequences of social interactions on phenotypic evolution.
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Affiliation(s)
- Corné de Groot
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich (LMU), 82152 Planegg, Martinsried, Germany.
| | - Rori E Wijnhorst
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich (LMU), 82152 Planegg, Martinsried, Germany
| | - Tom Ratz
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich (LMU), 82152 Planegg, Martinsried, Germany
| | - Myranda Murray
- Center for Biodiversity Dynamics (CBD), Department of Biology, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Yimen G Araya-Ajoy
- Center for Biodiversity Dynamics (CBD), Department of Biology, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Jonathan Wright
- Center for Biodiversity Dynamics (CBD), Department of Biology, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Niels J Dingemanse
- Behavioural Ecology, Department of Biology, Ludwig-Maximilians University of Munich (LMU), 82152 Planegg, Martinsried, Germany
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Martin JS, Jaeggi AV, Koski SE. The social evolution of individual differences: Future directions for a comparative science of personality in social behavior. Neurosci Biobehav Rev 2023; 144:104980. [PMID: 36463970 DOI: 10.1016/j.neubiorev.2022.104980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022]
Abstract
Personality is essential for understanding the evolution of cooperation and conflict in behavior. However, personality science remains disconnected from the field of social evolution, limiting our ability to explain how personality and plasticity shape phenotypic adaptation in social behavior. Researchers also lack an integrative framework for comparing personality in the contextualized and multifaceted behaviors central to social interactions among humans and other animals. Here we address these challenges by developing a social evolutionary approach to personality, synthesizing theory, methods, and organizing questions in the study of individuality and sociality in behavior. We critically review current measurement practices and introduce social reaction norm models for comparative research on the evolution of personality in social environments. These models demonstrate that social plasticity affects the heritable variance of personality, and that individual differences in social plasticity can further modify the rate and direction of adaptive social evolution. Future empirical studies of frequency- and density-dependent social selection on personality are crucial for further developing this framework and testing adaptive theory of social niche specialization.
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Affiliation(s)
- Jordan S Martin
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Switzerland.
| | - Adrian V Jaeggi
- Human Ecology Group, Institute of Evolutionary Medicine, University of Zurich, Switzerland.
| | - Sonja E Koski
- Organismal and Evolutionary Biology, University of Helsinki, Finland.
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