Social Behavior and Aggressiveness in Astyanax
Résumé
The species Astyanax mexicanus comprises both surface fishes (SF) that inhabit rivers and cave-adapted fishes (CF). These two morphs differ by numerous traits, including behaviors. One of the most puzzling questions concerns the social interactions between groups of SF, or groups of CF. SF have complex social interactions. Among other things, they have an increased propensity to school, react as a group to the presence of a predator, and establish hierarchies. On the contrary, CF tend to swim independently of one another, have lost their ability to react to predators, and exhibit reduced aggressiveness, although they are still able to interact to reproduce. The possibility that CF lost most of their social behaviors will be discussed, as well as the possible evolutionary forces that drove this evolution.