Ongoing Research Projects
We are involved in several projects that are in various stages of the publication cycle. This page is designed to give readers a feel for the types of projects we are currently working on.
Population & Conservation Genetics of Plethodon cinereus
We are currently collaborating with the Anthony/Hickerson (John Carroll University) and Kuchta Labs (Ohio University) on two projects that are making use of the molecular markers described in Cameron et al. (2017). The first of these projects is being headed up by Alex Cameron and uses spatially explicit analyses to examine the effects of urbanization within the Cleveland area on gene flow and connectivity in P. cinereus. The second of these projects is being led by Maggie Hantak and is examining the degree to which gene flow and genetic differentiation are associated with variation in color morph frequencies among populations of P. cinereus in Northern Ohio. A manuscript presenting the former of these projects was recently submitted to Conservation Genetics and a manuscript based on the latter is currently being drafted.
Ryan Lewis examining an anuran breeding pool at the C.L. Browning Ranch in Blanco County, Texas. This pool is typical of the leopard frog breeding sites that we are monitoring.
Anuran Population Monitoring
We were recently funded to monitor what we currently presume (based on distribution maps) to be the Rio Grande Leopard Frog (Rana berlandieri) population on the C.L. Browning Ranch in Blanco County, Texas. At present, we are exploring the ranch and identifying breeding pools, such as the one shown to the left. Once identified, we will monitor the growth and development of tadpoles, as well as the aquatic habitat characteristics of their larval pools. We are also funded to use genetic approaches to estimate the size of the ranch's breeding population, several demographic parameters, and the degree of connectivity (gene flow) across the ranch.
Because the Southern Leopard Frog (R. sphenocephala) is known to occur in two counties immediately adjacent to Blanco county and the current range limits of the Plains Leopard Frog (R. blairi) are also fairly close to the ranch, we plan on using genetic techniques to verify the species we're working with and if necessary determine whether hybridization is occurring.
Map showing the locations of Florida's two self-perpetuating Argentine Black-and-White Tegu populations. HC = Hillsborough County and MD = Miami-Dade County.
Results of a discriminant analysis of principal components based on 8 microsatellite loci for Red-backed Salamander (RBS) and Peaks of Otter Salamander samples from the Blue Ridge Mountains of Virginia.
Invasion Genetics of Argentine Black-and-White Tegus in Florida
In collaboration with Jared Wood, Stephanie Dowell, and Todd Campbell, we are using molecular genetic approaches to understand the invasion history and population genetic dynamics of Argentine black-and-white tegus (Salvator merianae) in Florida. We have sampled the two documented self-perpetuating populations of this species in Florida, one of which is in Miami-Dade County and the other of which is in Hillsborough County. We recently submitted a manuscript based on this work to Genetica. In this paper, we describe the results of several computational and statistical analyses that we performed on a data set composed of 14 microsatellite loci. Among other things, these analyses show that there is marked differentiation between these two regions and that populations in both regions have low genetic diversity. Moreover, comparison of several possible introduction pathways via approximate Bayesian computation suggests that populations in these two regions may be derived from separate escapes or releases from a common captive population associated with the pet trade.
Conservation Genetics of a Range-restricted Mountaintop Endemic
In collaboration with David Marsh, we are using molecular genetic approaches to assess whether the Peaks of Otter Salamander (Plethodon hubrichti), a range restricted mountaintop endemic that is only found along an approximately 19 km stretch of ridge line in the Blue Ridge Mountains of Virginia, is hybridizing with the widely distributed but morphologically and ecologically similar Eastern Red-backed Salamander (P. cinereus). David and his students have collected samples along several replicate transects that start in locales where only P. cinereus is found and pass through zones of contact into locales where only P. hubrichti is found. We have generated data from 8 microsatellites and are in the process of complementing these genomic markers with sequence data from two regions of the mitochondrial genome. As can be seen in the figure to the left, preliminary analyses suggest that hybridization among these two species either does not occur or is very rare. In addition to this finding, data from our microsatellite markers suggest that allelic richness and heterozygosity are both substantially higher in P. hubrichti than they are in P. cinereus--raising the possibility that P. cinereus is a comparatively recent invader to this portion of its range. We are currently in the early phases of using approximate Bayesian computation to test a variety of demographic models for these two species in hopes that this will shed additional light on the evolutionary history and conservation status of P. hubrichti.