research
Species Formation
What is a species and how do we recognize it? I am interested in patterns and processes of species formation. I use molecular data and tools from the fields of systematics and phylogeography to delineate boundaries within complexes of ‘cryptic species’ (two or more species erroneously classified as single species). My research has shown that many geographically widespread ‘species’ of frogs in Southeast Asia actually contain multiple, divergent, and sometimes sympatric evolutionary lineages that I hypothesize to be distinct species. These findings have implications for biogeography, community ecology, and conservation, and raise questions on how these sympatric lineages originated and are maintained.
Specimen-based Taxonomy
There is a pressing need to describe species diversity to provide conservation managers with information that can help mitigate loss of biodiversity from human activities. This is a critical role that systematists can take in the fight to preserve global health. I prepare species descriptions and taxonomic revisions of amphibians and reptiles, usually initiated by discoveries that I make during fieldwork. To date, I have described with colleagues over 40 species of Southeast Asian amphibians and reptiles.
Historical DNA
Bridging my interests in molecular systematics, phylogeography, and specimen-based taxonomy, I am excited by developments toward recovering usable DNA from preserved (including formalin-fixed) museum specimens. The vast majority of existing museum specimens of amphibians and reptiles were prepared prior to the molecular revolution, and therefore lack associated tissues that were preserved for molecular analyses. As a graduate student, I successfully modified a human forensics protocol to obtain mitochondrial and nuclear DNA from museum specimens of frogs, turtles, and amphisbaenians that were preserved as far back as the mid-1800s. I am optimistic that next-generation DNA sequencing technology will greatly advance these efforts. One of my current projects is trying to obtain DNA sequence data from historical, formalin-fixed museum specimens of the extirpated River Frog (Lithobates heckscheri) in North Carolina. This will allow assessing how the extirpated North Carolina population compared genetically to extant populations elsewhere in the species' range.
Fieldwork
I have maintained an active field program in Southeast Asia since I began working with the Wildlife Conservation Society Laos Program in 1998. My field program in Southeast Asia focuses on the countries of Laos, Cambodia, Thailand and Vietnam. The amphibians and reptiles of Laos and Cambodia are very poorly known, and most of my field efforts have been in those two countries. This fieldwork often entails logistically challenging expeditions to very remote areas.
I live and work in the beautiful U.S. state of North Carolina, home also to at least 165 native species of amphibians and reptiles (here are amphibian and reptile checklists). My fieldwork in North Carolina is primarily focused on improving genetic resources at the North Carolina Museum of Natural Sciences by obtaining voucher-associated tissue samples of amphibians and reptiles across the State. I have a particular interest in field sampling of slider turtles (Trachemys scripta complex) in support of a project on the extent of hybridization between the native yellow-bellied slider and the invasive red-eared slider. I also remain interested in the taxonomy of two-lined salamanders (Eurycea bislineata complex) in North Carolina.