The role of learning in the development of threat-sensitive predator avoidance by fathead minnows

The ability to recognize a potential predator and display adaptive antipredator behaviour is crucial to the survival of prey animals. Prey should gain a fitness advantage by displaying antipredator responses with an intensity that matches their risk of predation. Understanding how such responses develop is the focus of our current study. Many prey fish do not show innate recognition of predators. Thus, learning is necessary and a strong selection pressure should exist to make learning as efficient as possible. In this study we investigated the ability of predator-naïve fathead minnows, Pimephales promelas, to learn to recognize an unknown predator, brook charr, Salvelinus fontinalis. First, we conditioned minnows to recognize charr odour by exposing them to various concentrations of chemical alarm cues simultaneously with the odour of the charr and we subsequently tested them for recognition of this odour as a predation threat. Our objective was to test whether there was a match between the intensity of their antipredator responses during conditioning and recognition trials. Second, we tested whether minnows could learn to recognize charr through cultural transmission (i.e. by observing a conspecific responding to the odour of the predator) and we tested for a correlation between the intensity of response of the tutors during conditioning and the intensity of the learned responses by the observers during recognition trials. For both learning modes, the intensity of the response during the conditioning phase was retained during subsequent recognition trials. Our results suggest that minnows learn to respond more intensely to predation cues associated with high risk.