The focus of my research is in biodiversity genomics. My work investigates how ecological and evolutionary processes generate genetic and phenotypic diversity in natural populations, and these diversity patterns change across timescales in evolutionary radiations. This work integrates genomic and phenotypic data and encompasses lab, field and collections based studies of reptile and amphibian systems in ecosystems spanning tropical forests in Southeast Asia and Mexico, and deserts in western North America. Because much of my research relies on the use of genomic data, I am also interested in how well statistical phylogenetic and population genetic models fit empirical datasets and identifying the ways in which we can improve them to make the inferences we draw about under them more reliable. As an organismal and field biologist, I am deeply interested in natural history, the use of natural history museum collections for research and outreach, and applications of my research to conservation biology. My background includes work in wildlife and conservation biology with the California Department of Fish and Wildlife, the U.S. Forest Service, and U.C. Davis. My current research is focused on hybridization and its impact on diversification in whiptail lizards, a unique and interesting system for studying sex evolution and the impact of gene flow on speciation. Below is the Abstract of our current NSF grant “Species delimitation, hybridization and the origin of parthenogenesis in Whiptail lizards (Aspidoscelis)”:
Species are the basic unit of biological diversity. Scientists must be able to accurately recognize the boundaries between species, and the relationships among them, to understand fundamental biological processes and global patterns of biological diversity. The biology of some organisms makes recognizing species challenging. In particular, when species hybridize in nature it obscures the patterns of morphological and genetic variation that scientists usually use to recognize them. In some cases, hybridization is also associated with unique and interesting biological phenomena, such as changes in reproductive modes, chromosome number, or evolutionary adaptation. In this project, the research team will develop ways to accurately recognize species in a group of lizards where hybridization is common and species identification has been challenging: The North and Central American Whiptail lizards of the genus Aspidoscelis. In addition to improving methods for recognizing species, this research will increase the understanding of the effects of hybridization in the wild, as well as the evolution of reproductive modes in this group of lizards. The research activities will also provide training for a diverse team of scientists and students, many from groups typically underrepresented in science, in Hawaii and California.
Whiptails have diversified rapidly and experienced a large amount of introgressive hybridization, which makes them ideal for evaluating phylogenetic and population genetic methods for disentangling hybridization, lineage sorting, and systematic error. Hybridization between gonochoristic species has also repeatedly led to the formation of parthenogenetic lineages at a frequency that is essentially unique to this group. The research team will use genomic and morphological data to disentangle the effects of introgressive hybridization and lineage sorting on the patterns of divergence between all lineages of the Whiptail lizards, and use these results to infer the origins of parthenogenesis across the genus. By examining the geographic, temporal, and genomic dynamics of hybridization and introgression in Whiptails, the project will provide a better understanding of how gene flow impacts the speciation process in nature, and across evolutionary time. Comprehensively resolving patterns of speciation among Whiptails will also shed light on the processes associated with the frequent changes in reproductive mode that make them unique among vertebrates, and contribute to their ability to serve as a model system for other areas of inquiry across the life and biomedical sciences.