This project will test the hypothesis that divergent natural selection between predator regimes has driven adaptive divergence between populations within a species (microevolution) and between species within a genus (macroevolution). Using a biomechanical approach, the study will test predictions of how natural selection in different predator regimes should favor different body forms and swimming capabilities in livebearing fish of the genus Gambusia (mosquitofishes). The project will use comparative analyses to assess evolutionary changes in body shape, prolonged swimming performance, and fast-start swimming performance associated with colonization of low- and high-predation environments. The study will further examine the genetic basis of trait differences, and test biomechanical predictions of morphology-performance relationships within and between species (revealing the causal connections between body form and swimming). The methodological approach of the study should reveal the relative importance of natural selection and random genetic drift in the evolution of traits at the micro- and macroevolutionary scales.
The study quantitatively examines a fundamental question in evolutionary biology-whether processes driving microevolutionary divergence can explain macroevolutionary patterns. The work should provide an important contribution to the study of adaptive evolution, particularly the role of predation in evolutionary diversification and the utility of a biomechanical approach in understanding the functional basis of adaptive divergence. The project will further help train several students in both laboratory- and field-based research, and be widely disseminated to the scientific community, as well as the broader public.
