Exposure to predation generates personality in threespined sticklebacks ( Gasterosteus aculeatus )

A perplexing new question that has emerged from the recent surge of interest in behavioural syndromes or animal personalities is--why do individual animals behave consistently when behavioural flexibility is advantageous? If individuals have a tendency to be generally aggressive, then a relatively aggressive individual might be overly aggressive towards offspring, mates or even predators. Despite these costs, studies in several taxa have shown that individuals that are more aggressive are also relatively bold. However, the behavioural correlation is not universal; even within a species, population comparisons have shown that boldness and aggressiveness are correlated in populations of sticklebacks that are…