Predation mediated population divergence in complex behaviour of nine-spined stickleback (Pungitius pungitius)

The proximate and ultimate explanations for behavioural syndromes (correlated behaviours - a population trait) are poorly understood, and the evolution of behavioural types (configuration of behaviours - an individual trait) has been rarely studied. We investigated population divergence in behavioural syndromes and types using individually reared, completely predator- or conspecific-naive adult nine-spined sticklebacks (Pungitius pungitius) from two marine and two predatory fish free, isolated pond populations. We found little evidence for the existence of behavioural syndromes, but population divergence in behavioural types was profound: individuals from ponds were quicker in feeding, bolder and more aggressive than individuals from marine environments. Our data reject the hypothesis that behavioural syndromes exist as a result of genetic correlations between behavioural traits, and support the contention that different behavioural types can be predominant in populations differing in predation pressure, most probably as a result of repeated independent evolution of separate behavioural traits.