Behavioural correlations across situations and the evolution of antipredator behaviour in a sunfish–salamander system

Abstract

Behavioural correlations are at the heart of understanding how conflicting demands shape the evolution of ecologically important behaviours. Many studies have focused on the effects of negative behavioural correlations generated by time budget conflicts within situations. We examined an alternative possibility that involves positive behavioural correlations due to behavioural carryovers across situations. Specifically, we examined the role of behavioural carryovers in governing antipredator responses of streamside salamander larvae, Ambystoma barbouri, to predatory green sunfish, Lepomis cyanellus. Earlier work showed that these larvae suffer heavy sunfish predation due to high larval exposure to fish (high proportion of time spent out of refuge). Earlier work also showed that paradoxically, despite selection pressure from fish, these larvae show higher exposure in the presence of fish (poorer antipredator behaviour) than a sister species that inhabits fishless, ephemeral ponds. The standard time budget trade-off between feeding and antipredator behaviour does not appear to explain the observed antipredator behaviours. Instead, the present study shows that the relatively large proportion of time that larvae spend out of refuge (exposed) in fish pools in the daytime can be explained in part by behavioural correlations across situations. Specifically, larvae showed positive correlations among individuals in their daytime exposure in fish pools, nighttime exposure in fish pools, and exposure in fishless pools. The benefits of high exposure in fishless conditions (associated with high feeding and developmental rates) and high exposure in fish pools at night (necessary to drift out of fish pools) have apparently overridden the predation cost of being exposed in fish pools in the day. Behavioural correlations across situations might often result in ecologically important behaviours that appear maladaptive in an isolated context. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.