Does aggression and explorative behaviour decrease with lost warning coloration?

For prey, many behavioural traits are constrained by the risk of predation. Therefore, shifts between warning and cryptic coloration have been suggested to result in parallel changes in several behaviours. In the present study, we tested whether changes in chromatic contrast among eight populations of the strawberry poison-dart frog, Dendrobates pumilio, co-vary with behaviour, as expected if selection is imposed by predators relying on visual detection of prey. These eight populations are geographically isolated on different island in the Bocas del Toro region of Panama and have recently diverged morphologically and genetically. We found that aggression and explorative behaviour were strongly correlated and also that males tended to be more aggressive and explorative if they belonged to populations with conspicuously coloured individuals. We discuss how evolutionary switches between predator avoidance strategies and associated behavioural divergence between populations may affect reproductive isolation.