Evolutionary Ecology of Amphibians and Reptiles

Much of my research before coming to Oklahoma State University focused on the evolutionary ecology of amphibians and reptiles, particularly turtles in the family Emydidae. Emydidae includes many well known North American Turtle species, such as the Eastern Box Turtle (Terrapene carolina), the Painted Turtle (Chrysemys picta), and the  Pond Slider (Trachemys scripta). It has been an ideal study system for me because the family is geographically very widespread and species in it are ecologically incredibly diverse.  It is one of the very few families of vertebrates to include aquatic, terrestrial, and semi-terrestrial species as well as herbivorous, carnivorous, and omnivorous species.  It is also among the few terrestrial clades to exhibit a “reverse latitudinal diversity gradient,” where more species occur in temperate than tropical regions.  Some species in the genus Graptemys also exhibit  some of the most extreme sexual size dimorphisms known in tetrapods, with adult females that are more than twice as long as adult males and roughly an order of magnitude more massive.

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Topics I have addressed in emydids include the origins of large scale patterns of species richness, the evolution of ecological specialization, the origins of large scale patterns of community structure, and the evolution of sexual size dimorphisms. One theme that runs through much of this work is that niche conservatism and dispersal limitation greatly influence emydid biodiversity at large spatial scales. Other projects in herpetology include the origins of large scale patterns of species richness in hylid frogs, the evolution of endosulfin resistance in North American frogs and the evolution of phenotypic plasticity in more than two dozen species of North American ranid, bufonid, and hylid frogs and parallel patterns of adaptive evolution the turtle families Emydidae and Geoemydidae.