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Genome-Scale Phylogeographic Analysis of Desmognathus Salamanders
With an exhaustive "ecodrainage" sampling technique, this NSF supported research project will analyze >1,500 Desmognathus populations. The study will use next-generation genomic sequencing of DNA to reveal the true genetic diversity of the genus. These data will allow researchers to understand the evolutionary history of divergence, hybridization, and species boundaries from a genetic perspective, using modern species-delimitation methods. Overall, this research will generate a robust and fully-sampled estimate of the true number of Desmognathus species, their morphological variation, and their geographic range. This research will likely yield an increased number of Desmognathus species, while also showing a complex history of introgression, hybridization, and incomplete ecological speciation.
Comparative Phylogenomics of Co-distributed Taxa from Forest Floors and Riparian Corridors in the Southeastern United States
For nearly twenty years I have been systematically collecting samples within level iv ecoregions and independent river drainages across the southeastern United States. The goal of this project is to compare taxa at different taxonomic levels; species, genera, family, and phyla. Sampling has focused on multiple genera and families of salamanders, terrestrial gastropods, apheloriine millipedes and mygalomorph spiders. Since these taxa are found in microsympatry there is an opportunity to examine the role of geological and drainage history, ecosystem and community structure on the diversification of these groups across different time and taxonomic scales. Are there broad patterns that have similarly shaped the diversity of all these taxa, or have historical contingencies differentially shaped the diversification of these co-distributed taxa? The answers to these questions may have important implications for our understanding of the speciation process.
Factors Affecting Gene Flow and Population Structure of Neuse River Waterdogs
The Neuse River Waterdog is a North Carolina endemic, found only in the Neuse and Tar River drainages and is currently under consideration for federal endangered or threatened status. Together with colleagues in the NC WRC and US F&W, we have sampled most of the known historical localities for this species. Tissues were collected and will be used to generate a 3RAD database to examine gene flow and connectivity between populations.
In a related project supported by a Duke Energy Water Resources Fund Grant, we have collected water samples and water quality data from 50 of the waterdog sampling sites. This data will be used to compare characteristics between sites with and without waterdogs. We have also developed an eDNA protocol that may be able to supplement our existing database about where this species occurs.
Distributional Extent of the South Mountain Gray Cheeked Salamander
The South Mountain Gray Cheeked Salamander has only been reported from a handful of sites in and immediately around South Mountains State Park. Beginning in 2010, I have modeled the habitat of this species as part of my Field Biology class and each year since that time we have ground-truthed these models. Through the cooperation of many private land owners, we have been able to locate additional populations of this species, greatly expanding the known distributional extent. Moreover we have identified the region of contact with the Blue Ridge Gray Cheeked Salamander. Future studies in the lab will investigate the nature of the interaction of these two species in the region of contact.
A Genomic Investigation of the Contact Zone Between "Northern" and "Southern" Two-lined Salamanders
The earliest divergence in two-lined salamanders is between two groups that can be categorized as "northern" and "southern". These groups do not reflect current taxonomy, with the "northern" group occurring well into range of what is currently recognized as Southern Two-lined Salamanders. We have been examining the contact zone between the "northern" and "southern" groups to determine the nature of their interactions and to test the hypothesis of species status for these salamanders.
Phylogeography of Seepage Salamanders
Seepage salamanders have a moderate sized range spanning >500 km that spans multiple drainages and ecoregions. While these salamanders can be very abundant in localized habitat, their small size and requirement for cool, moist conditions probably limits dispersal. When I started this project over ten years ago I thought it would be relatively straightforward. However, the patterns of diversity in this group of salamanders is exceeding difficult to comprehend. Some genetic groups seem to have very large distributions while other groups have small local distributions that are completely surrounded by the widely distributed groups. In some cases they appear to behave as separate species yet there are no apparent biogeographic barriers in many cases. Moreover there are interactions between other more distant groups that suggest conspecificity. To date we have collected data from ~300 individuals sampled across >80 separate populations. We are integrating complete mitochondrial genomes, anchored hybrid enrichment loci and morphological data to test speciation hypotheses in these salamanders.
Phylogeography and Taxonomic Status of
Three-lined Salamanders
The taxonomic status of three-lined salamanders has been debated over the years. At times it has been treated as a subspecies of the long-tailed salamander but it is currently afforded species status. Much of this debate has centered over the interpretation of color patterns near the region of contact. The pigmentation has variously been interpreted as both supporting introgression and as indicating no hybridization was taking place. We have sampled three-lined salamanders across the species distribution and have found unequivocal evidence of hybridization that is reflected both in morphology and in DNA sequence data. We are presently sampling additional populations from the region of contact to determine the correct taxonomic status of these salamanders.
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