Who dares does not always win: risk-averse rockpool prawns are better at controlling a limited food resource

Abstract

Animal ‘personality’ – the phenomenon of consistent individual differences in behaviour within populations – has been documented widely, yet its functional significance and the reasons for its persistence remain unclear. One possibility is that among-individual behavioural variation is linked to fitness-determining traits via effects on resource acquisition. In this study, we test this idea, using rockpool prawns (Palaemon elegans) to test for a correlation between ‘high-risk exploration’ and the ability to monopolise a limited resource. Modified open field trials (OFTs) confirmed that consistent among-individual (co)variation in high-risk exploratory behaviours does exist in this species, and multivariate analysis shows trait variation is consistent with a major axis of personality variation. Subsequent feeding trials in size-matched groups where competition was possible revealed a high repeatability of feeding duration, used here as a proxy for RHP (resource holding potential). We found significant negative correlations between feeding duration and two ‘risky’ behaviours, such that individuals that took fewer risks fed more. Our results are not consistent with the widely hypothesised idea of a ‘proactive syndrome’ in which bolder, risk-taking personalities are positively associated with RHP. Rather they suggest the possibility of a trade-off, with some individuals successful at monopolising limited, high-value resources, while others are more willing to engage in potentially risky exploration (which may increase the likelihood of encountering novel resource patches). We speculate that alternative strategies for acquiring limited resources might thereby contribute to the maintenance of personality variation observed in wild populations