Ideal despotic distributions in convict cichlids (Amatitlania nigrofasciata)? Effects of predation risk and personality on habitat preference

Abstract

Habitat structure may reduce predation risk by providing refuge from predators. However, individual behavioural differences (i.e. aggression, shyness/boldness) may also cause variation in competitive ability or tolerance of predation risk, resulting in differences in habitat preference. We manipulated habitat structure to explore the role of predation risk on foraging success, aggression and habitat use in an ideal free distribution experiment using the convict cichlid (Amatitlania nigrofasciata). Groups of four same-sized fish competed for food in two patches that differed in habitat complexity, with and without exposure to a predator model; all fish were then given a series of individual behavioural tests. Fish showed repeatable differences in dominance status, foraging success, aggression and habitat use over the 14-day trials. Dominants always preferred the complex habitat, while subordinates used the open habitat less after exposure to a predator model. Although an equal number of fish were found in either habitat in the absence of a predator, dominants appeared to exclude subordinates from the complex habitat, supporting an ideal despotic distribution. The individual behavioural assays predicted habitat use, but not foraging success or dominance; fish that were aggressive to a mirror were more frequently found in the open habitat during the group trials.