Among-individual variation in behaviour and its effect on reproductive success

Understanding the evolution of animal personality requires knowledge of how selection acts on this form of behavioural variation. While there is good evidence that among-individual variation in behaviour is subject to natural selection from predation, less is known of how personality might affect reproductive success. Here, we observed the sex-specific patterns of selection acting on among-individual behavioural variation in the Australian field cricket, Teleogryllus oceanicus, through the effects of behaviour on reproductive success. In this species males and females show among-individual variation in boldness and exploratory behaviour, both of which are expected to influence encounter rates with potential mates. We measured the behaviour of males and females and obtained two estimates of individual fitness, the number of mates and number of offspring produced, for individuals interacting freely over a period of 1 week within a simulated natural environment. Male but not female crickets changed their exploratory behaviour after they had interacted with conspecifics in the simulated natural environment. We found evidence of significant sexual selection acting on males in the form of a positive Bateman gradient. While also positive, the Bateman gradient for females was not statistically significant. Selection analyses provided little evidence of linear, quadratic or correlational selection acting on male or female boldness or exploratory behaviour. We conclude that among-individual variation in these behaviours is unlikely to be subject to selection via their effects on reproductive success.