Summary: Dingemanse et al. (2007)

Animal populations show individual differences in suites of correlated behaviours ("temperament", "animal personality") across different contexts ("behavioural syndromes"). Population variation in behavioural syndrome may exist for two reasons: 1) natural selection favours covariance in a trait and syndromes will evolve in response ("adaptive hypothesis"); and 2) stochastic processes (e.g. mutation, drift, founder effects, gene flow) maintain variation. Dingemanse et al. (2007) examined the adaptive hypothesis using a comparative approach. They measured 5 different behaviours (categories: aggression, general activity, exploration-avoidance-novel foods, novel or altered environments) across 12 different populations (6 predator-sympatric, 6 predator-naive) of three-spined stickleback (Gasterosteus aculeatus) and assessed whether the differences in behaviour varied consistently depending on the environment. Their results confirm the prediction of the adaptive hypothesis. They found that behavioural syndromes are not always the same in different types of population, implying that population variation in behavioural syndromes is not a result of stochastic evolutionary processes. They suggest that, in sticklebacks, behavioural syndromes are correlated with the presence of predators. Dingemanse et al. (2007) suggest that behavioural syndromes are not fixed according to physiological or genetic constraints and arise from adaptive evolution, where a behaviour is favoured because it is the most optimal trait in that environment.