Contribution of genetics to the study of animal personalities: a review of case studies

The need for evolutionary studies on quantitative traits that integrate genetics is increasing. Studies on consistent individual differences in behavioural traits provide a good opportunity to do controlled experiments on the genetic mechanisms underlying the variation and covariation in complex behavioural traits. In this review we will highlight the contribution of genetic studies in animal personality research. We will start with reviewing the evidence that shows how much variation in animal personality traits is genetic, and connect this to knowledge from human personality studies. We will continue by considering the nature of that variation, its generation and maintenance. Finally we will point to further possibilities for studying the genetics of animal personalities. We will underline the importance of integrating both proximate and ultimate approaches when studying the evolution of animal personalities.