EVOLUTION OF ADAPTIVE VARIATION IN ANTIPREDATOR BEHAVIOR

In many species of fish, behaviour varies adaptively amongst populatio ns in response to predation risk. One of the best examples is provided by the guppy, Poecilia reticulata, in Trinidad. Although separated by distances of a few km, or less, guppy populations vary in terms of pr edator assessment and avoidance, schooling, foraging behaviour, resour ce defence, female choice and mating tactics. We show that there are b ehavioural costs (such as lower levels of individual aggression and re duced female choice) associated with selection for a heightened antipr edator response. In the majority of cases population variation in gupp y behaviour can be clearly linked to the predation regime. Nevertheles s, we have begun to uncover situations where there is behavioural dive rgence amongst populations apparently experiencing equivalent risk. We consider explanations for these differences including the possibility that they may be related to high levels of genetic divergence.