A test of the predator naiveté hypothesis using desert pupfishes: History of isolation does not matter

Many desert fishes, which evolved in isolated aquatic “islands” with limited predation pressure, have been severely impacted by non-native predators. These impacts have been attributed to the evolutionary loss of antipredator competence, known as the predator naiveté hypothesis. Recent work provided support for this hypothesis for one desert fish species. We sought to examine the generality of predator naiveté hypothesis by evaluating antipredator competence in five populations of Red River pupfish (Cyprinodon rubrofluviatilis), a species that occupies habitats that vary in the degree of isolation and levels of fish species richness. Fish were exposed to conspecific chemical alarm cues released from damaged epidermal tissue as a general assay of antipredator response. We found that pupfish from all five populations exhibited antipredator behavior in response to alarm cues, regardless of isolation duration or exposure to predation risk. These data demonstrate that antipredator responses to alarm cues are conserved in pupfishes even after prolonged periods of isolation from piscivorous species.