Integrative evolutionary biology of livebearing fishes
My research focuses on understanding the evolutionary consequences of variable environments, primarily in fishes. I integrate ecological, physiological, genetic, and behavioral approaches to address the following questions: How does environmental variation maintain evolutionary potential (i.e., genetic variation) within populations? What are the environmental drivers and mechanisms of adaptive divergence between populations/species? How do these same environmental drivers influence diversification at macroevolutionary scales?
Tailspots in X. variatus are an interesting system to study the maintenance of genetic variation within populations. Controlled by different alleles at a single locus, tailspot patterns exhibit gene-by-environment interactions with temperature. Combining field studies, spatial ecology, physiology, and behavior have provided a number of insights into the roles of natural and sexual selection in maintaining polymorphism.
Divergence in thermal niches between closely related species can help provide clues of whether and how temperature influences species divergence. Integrating spatial ecology, physiology in a common garden, and phylogenetic comparative methods, we've shown considerable adaptive evolution of thermal limits across Xiphophorus, and multiple species pairs that have diverged along elevational gradients.