Research
Program
My lab focuses on exploring the factors that shape biological diversity at the level of individuals, populations, and communities. Through investigation of environmental variation and fine-scale biogeography, we are interested in understanding variation in organismal traits (e.g. physiological performance, life history, and disease resistance), the demography of populations, and the composition of assemblages. To study these relationships we use an approach that combines characterization of genetic variation using molecular markers with fieldwork to describe the ecological context for evolutionary change. Most often amphbians and reptiles are the organisms that capture our interest. Further details of recent and ongoing projects in the lab are described below.
Molecular
Ecology of Galápagos
Lava Lizards (Microlophus spp.)
A central goal of evolutionary biology is to understand the origin and maintenance of genetic and phenotypic diversity. Studies of populations resident on oceanic islands have provided critical insight into these processes. Galápagos lava lizards are a group that lends itself to rigorous evolutionary study in this tradition. Populations of lava lizards are distributed across an array of islands and islets that are geographically proximate and share a well-defined geological history. Considerable variation in morphology, life history, ornamentation and physiological performance exists within and among these populations. We have shown that gene flow is unlikely to limit phenotypic divergence within a small island that exhibits a marked shift in habitat structure. Meanwhile, genetic drift in isolation is strongly implied in populations that were fragmented when sea levels rose following glacial melting at the end of the Pleistocene. These results suggest that an interaction between drift and selection is likely to have shaped the recent diversification of these lizards.
Conservation
Genetics and Ecology of Midwest Vertebrates
Habitat fragmentation and modification are characteristic of the landscape of the midwestern United States over the past 200 years. Conversion of land for agricultural use, the development of roads, and urbanization is expected to restrict dispersal among populations. Meanwhile, habitat quality is influenced by land use practices. Our research investigates the direct effects of these factors and their interrelationships. For example, our work has shown that the distribution of terrestrial salamander (Plethodon cinereus) populations is impacted by woodlot size in northeast Indiana. Meanwhile, dispersal dynamics rather than water quality appears to have the greatest influences on the genetic population structure of a fish species (Semotilus atromaculatus) that occupies agricultural ditches.
