Maternal inheritance and exploratory-boldness behavioural syndrome in zebrafish

Correlated behavioural traits (behavioural syndromes) influence ecological interactions and, in turn, how natural selection shapes the evolution of behaviour. A major axis of intraspecific behavioural variation is the exploratory-boldness behavioural syndrome. Here, we describe how we sorted wild-caught zebrafish (Danio rerio) for increasing exploratory tendency using a serial open field maze. We then transferred test fish to a predator-inspection apparatus. Highly exploratory individuals spent more time near a novel predator than non-exploratory individuals, showing behavioural consistency indicative of an exploratory-boldness behavioural syndrome. We then bred the zebrafish to create F-1 offspring from four crosses: (1) exploratory x exploratory, (2) non-exploratory x non-exploratory, (3) exploratory females x non-exploratory males and (4) non-exploratory females x exploratory males. F-1 offspring were tested in a miniature serial open-field maze similar to the one used to sort the adults. Offspring of exploratory females were always highly exploratory regardless of the behavioural traits of the father suggesting that maternal effects may influence expression of exploratory-boldness behavioural syndrome in zebrafish.