Data for: Predation risk and the evolution of a vertebrate stress response: parallel evolution of stress reactivity and sexual dimorphism

Predation risk is often invoked to explain variation in stress responses. Yet, the answers to several key questions remain elusive, including: 1) how predation risk influences the evolution of stress phenotypes, 2) the relative importance of environmental versus genetic factors in stress reactivity, and 3) sexual dimorphism in stress physiology. To address these questions, we explored variation in stress reactivity (ventilation frequency) in a post-Pleistocene radiation of live-bearing fish, where Bahamas mosquitofish (Gambusia hubbsi) inhabit isolated blue holes that differ in predation risk. Individuals of populations coexisting with predators exhibited similar, relatively low stress reactivity as compared to low-predation populations. We suggest that this dampened stress reactivity has evolved to reduce energy expenditure in environments with frequent and intense stressors, such as piscivorous fish. Importantly, the magnitude of stress responses exhibited by fish from high-predation ...