Evolutionary causes and consequences of consistent individual variation in cooperative behaviour

Abstract

Behaviour is typically regarded as among the most flexible of animal phenotypic traits. In particular, expression of cooperative behaviour is often assumed to be conditional upon the behaviours of others. This flexibility is a key component of many hypothesized mechanisms favouring the evolution of cooperative behaviour. However, evidence shows that cooperative behaviours are often less flexible than expected and that, in many species, individuals show consistent differences in the amount and type of cooperative and non-cooperative behaviours displayed. This phenomenon is known as 'animal personality' or a 'behavioural syndrome'. Animal personality is evolutionarily relevant, as it typically shows heritable variation and can entail fitness consequences, and hence, is subject to evolutionary change. Here, we review the empirical evidence for individual variation in cooperative behaviour across taxa, we examine the evolutionary processes that have been invoked to explain the existence of individual variation in cooperative behaviour and we discuss the consequences of consistent individual differences on the evolutionary stability of cooperation. We highlight that consistent individual variation in cooperativeness can both stabilize or disrupt cooperation in populations. We conclude that recognizing the existence of consistent individual differences in cooperativeness is essential for an understanding of the evolution and prevalence of cooperation.

Cooperation in wild Barbary macaques: factors affecting free partner choice

“…Individuals may be less willing to cooperate with higher ranking partners, which often monopolise experimental apparatuses that dispense food (Chalmeau and Gallo 1993;de Waal and Davis 2003;Drea and Carter 2009;Suchak et al 2014). The temperament of the subjects may also affect cooperation (Bergmüller et al 2010;McNamara and Leimar 2010). In rooks, bolder birds were more willing to approach the experimental apparatus than shier birds, and subjects performed better in a cooperative task when paired with a bolder than shier partner (Scheid and Noë 2010).…”

Hormonal mechanisms of cooperative behaviour

“…Variation might simply be due to noise around an optimum, or it could be owing to frequency-dependent selection on a distribution of strategies. To make things more complex, seemingly non-adaptive behaviour might result from correlations across contexts that may lead to behavioural syndromes (for example 'be aggressive and don't help' or 'be non-aggressive and help ', Bergmü ller et al 2010). Variation could result from genetic differences, but ontogenetic effects could also be important ('phenotypic defectors' in Sherratt & Roberts 2001) because they can affect behaviour via body condition or via individual and/or social learning.…”

The Integration of Sociality, Monoamines, and Stress Neuroendocrinology in Fish Models: Applications in the Neurosciences

“…For instance, the existence of behavioural polymorphisms between individuals and populations of a single species may arise in response to ecological or social challenges-constraints, thus imposing on individuals the need to adapt to different contexts (Sih & Bell, 2008;Bergmuller et al, 2010). Such adaptive behavioural correlations usually underline physiological trade-offs that will play a key role in explaining much of an animal's plasticity to perform within their socio-environmental challenges and which should ultimately bear fitness consequences.…”