Data from: Predicting ecological and phenotypic differentiation in the wild: a case of piscivorous fish in a fishless environment

Environmental variation drives ecological and phenotypic change. But how predictable is differentiation in response to environmental change? Answering this question requires the development and testing of multifarious a priori predictions in natural systems. We employ this approach using Gobiomorus dormitor populations which have colonized inland blue holes differing in the availability of fish prey. We evaluated predictions of differences in demographics, habitat use, diet, locomotor and trophic morphology, and feeding kinematics and performance between G. dormitor populations inhabiting blue holes with and without fish prey. Populations of G. dormitor independently diverged between prey regimes, with broad agreement between observed differences and a priori predictions. For instance, in populations lacking fish prey, we observed male-biased sex ratios, greater use of shallow-water habitat, and larger population diet breadths owing to greater individual diet specialization. We further found predictable differences in body shape, mouth morphology, suction generation capacity, strike kinematics, and feeding performance on different prey types, consistent with G. dormitor adaptation to piscivory when coexisting with fish prey and to feeding on small invertebrates in their absence. Our results suggest great promise in our ability to predict population responses to changing environments, an increasingly important capability in a human-dominated, ever-changing world.