Unravelling the proximate causes of the aggression-boldness behavioural syndrome in zebrafish

Many animal species exhibit behavioural syndromes, groups of two or more behaviours that are linked together across different environments or time points. Behavioural syndromes give rise to stable behavioural profiles and have been likened to personality in humans. However, the proximate causes (or mechanisms) that underlie the clustering of behaviour are not well understood. In this review, we examine the proximate causes of the aggression-boldness behavioural syndrome, which constitutes a positive correlation between aggression, boldness and exploratory activity. In particular, we will focus on novel insights that have been gained from zebrafish, a genetically tractable behavioural model which can be used to study the mechanistic basis of behaviour. Studies of the proximate causes of behavioural syndromes provide us with the opportunity to understand the clustering of behaviours - and perhaps even the basis of personality - at the molecular level. Thus, this exciting field not only promises to bring novel insights into animal behaviour, but also forces us to rethink our own personalities as well.