The effects of the social environment and physical disturbance on personality traits

The environment can have a considerable impact on behaviour. The social environment is predicted to be a particularly important driver of behavioural variation and evolution through the indirect genetic effects that arise whenever individuals interact with conspecifics. We used male Australian field crickets, Teleogryllus oceanicus, to examine the effects of changes in the social environment (recorded acoustic sexual signals of other males) on the expression and consistency of boldness, activity and exploration, and their between-individual covariation. Switching from a silent environment to being exposed to male acoustic sexual signals resulted in crickets becoming less bold, active and explorative. Switching from an acoustic to a silent environment resulted in increased boldness and activity. We also looked at the effects of changes in the nonsocial environment via a physical disturbance that mimicked the presence of a potential predator (mechanical shaking). The effects of physical disturbance (and changes thereof) on behaviour were far less pronounced than the effects of changes in the social environment. Neither the repeatability of nor correlations between behaviours were affected by changes in physical disturbance. Only the average level of exploration was affected significantly when crickets were moved from an undisturbed to a disturbed environment, with crickets becoming less explorative. Although changes in the social and the nonsocial environment affected the repeatability of and correlations between some of the behaviours measured, changes in the social environment had the greater effect. We discuss the ecological and evolutionary implications of our findings and how they relate to our current understanding of social and nonsocial environmental effects on behaviour.