The Evolution of Animal Personality Variation

Abstract

Abstract In many species of animals individual behaviour differs, yet is consistent over time and in an array of different environments; in other words, these animals display ‘personality’ variation. This may emerge not by chance, but, instead, is shaped by selective processes favouring individuals who display a differentiated behavioural phenotype. Indeed, personalities are known to affect important activities such as resource acquisition, survival and reproduction – which, cumulatively, impact an individual's fitness. We currently lack the insights and technology needed to fully characterise the genetics and physiology of most ecologically relevant behaviour; however, much can be gained by adopting an adaptive approach to consider the evolutionary processes that might have driven the emergence and maintenance of stable behavioural variation. Such an exercise will allow us to develop a priori hypotheses about the mechanisms underlying the behaviour, and to conduct powerful empirical studies examining how individualised behaviour impacts the life histories of a variety of species. Key Concepts: In many animal species, individuals differ predictably in their behaviour; this consistent behavioural variation is often referred to as ‘animal personalities’ (or ‘behavioural types’, ‘coping styles’, ‘temperament’ and ‘behavioural syndromes’). Expression of personalities can have significant impacts on activities such as resource acquisition, survival and reproduction – and, therefore, may influence fitness. A variety of factors may contribute for interindividual variation within populations; these include mutation, stochasticity, strong tradeoffs, spatiotemporal fluctuations, condition dependence and state dependence and negative frequency dependence. Personalities can also be thought of as individual behavioural specialisation; this may arise as a result of life history tradeoffs, state‐dependent feedback, adaptive packaging of suites of traits and adaptive consistency. Certain personalities may not be beneficial under some circumstances; however, when their effects are considered across the range of different circumstances that an animal will experience throughout its lifetime, these personalities will ultimately prove beneficial – otherwise they will not be maintained in the population. The study of animal behaviour is useful for generating testable hypotheses about how genetics and physiology may underpin ecologically relevant behaviour, as well as for predicting the exact mechanisms that might link these traits.