Pitvipers have been a research focus of mine since graduate school and I am interested in all aspects of their biology. Pitvipers are an excellent group of organisms to test various evolutionary phenomena because of their numerous evolutionary radiations, unique natural history characteristics and medical relevance as a venomous species. Although I spend most of my time studying their evolutionary history, biogeography and evolutionary patterns using phylogenetics, we have several on going projects dealing with different aspects of pitviper evolution. Current research includes continued work resolving the phylogenetic relationships of New World Crotalinae, testing various biogeographic hypotheses and examining patterns of venom evolution in select species.
Florida Water Snakes
An on-going study in the lab aims to determine the evolutionary and taxonomic status of two water snakes: the Salt Marsh Snake (Nerodia clarkia) and the Banded Water Snake (Nerodia fasciata). Previous work has provoked debate as to whether these two groups represent species with independent evolution trajectories or a single species exhibiting phenotypic diversity. To address this question we are employing phylogenetic and population genetic techniques to determine what genetic structure exists among Florida water snakes, and if current taxonomy accurately reflects this. Other questions of interest are if there is correlation between geographic structure and population genetics of these species, and if environmental factors such as water salinity impact their genetics.
In collaboration with Dr. Alex Cole, we are investigating the evolutionary relationships of the medically important bacteria Staphlococcus aureus. Current scientific literature generally refers to clinical and community strains of S. aureus as distinct groups due to differences in pathogenic symptoms caused by horizontally transposable gene elements. However, work examining the relationships of various S. aureus strains in a phylogenetic framework suggests that such distinctions may be premature. Our continued exploration evaluating the evolution and population structure of these bacteria will give insight into the true evolutionary relationships and will inform more effective treatment and classification of S. aureus.
We have recently started an investigation of the habitat usage and dispersal barriers of the gopher tortoise (Gopherus polyphemus) at Kennedy Space Center. Gopher tortoises are a keystone species because the numerous burrows that they dig which are used as a means of refuge by over 360 other species. Despite their importance to ecological communities, gopher tortoises face threats from many of anthropogenic sources. At Kennedy Space Center, we are investigating how tortoises are using an intermediate habitat we define as wildlife corridor between coastal and inland habitats. This work will impact the conservation and management planning of gopher tortoises and many other terrestrial species.
A new project being started in the lab includes examining the population genomics and subspecific taxonomy of mole skinks (Plestiodon egregius). Currently five subspecies have been described, ranging throughout Florida and into Georgia and Alabama. The subspecies P. e. lividus has been classified as threatened since 1987. In addition, P. e. egregius is considered a species of special concern in Florida. Both P. e. egregius and P. e. insularis are now under review as candidate species for listing for U.S. Fish and Wildlife. By examining the genomics of mole skinks we will be able to determine whether current subspecies are confirmed by molecular data, which will inform the decision to list any subspecies as threatened or endangered.
A variety of projects in the lab utilize phylogenetics to answer questions relating to the biogeography of various groups. This particular project focuses on measuring the effect of the American Cordillera on the genetic structure of two broadly distributed snake species: glossy snakes (Arizona elegans) and long-nosed snakes (Rhinochelius lecontei). Genetic structure as a result of this barrier has been documented in other snake species including black-tail rattlesnakes and western diamondback rattlesnakes. The findings from this project will further elucidate our understanding of vicariance’s effect on evolution and allopatric speciation.