Population Genetics and Conservation of Texas Hill Country Eurycea




Lucas, Lauren K.

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The Texas Hill Country is composed of isolated aquatic habitats that are inhabited by a variety of endemic aquatic organisms, many of which have restricted ranges and are threatened by human usage of aquatic resources. Among this fauna are the spring associated, neotenic salamanders of the genus Eurycea. I examined mitochondrial and nuclear sequence variation of seven Eurycea populations to address the following questions: 1) to what extent does gene flow occur among these populations?, 2) do river systems or aquifers serve as conduits for gene flow in this system?, and 3) what is the status of each population, measured by effective population size and an exponential growth rate parameter? The number of pairwise migrants per generation based on non-equilibrium pairwise migration rates was less than one for all pairs of populations except Jacob's Well and Devil's Backbone. There was a significant correlation between non-equilibrium migration rate and geographic distance. Partial mantel tests revealed that what little gene flow occurs among populations does not appear to be facilitated by current river systems, but may be facilitated by aquifer connections. Each of the populations sampled in this study likely constitutes a unique entity and should be managed as such. Population size estimates were reasonably large ( approximately 178, 100-1, 720,600) and were coupled with no evidence of population decline. The Comal Springs population had the largest estimated population size and appears to be growing. I also examined genetic variation and structure within the San Marcos Springs Eurycea population (E. nana) and between this wild population and the refuge population housed at the San Marcos National Fish Hatchery and Technology Center. There was no significant genetic structure among three sites sampled within the wild population Estimates of genetic diversity for the wild and refuge populations were not significantly different.



Brook salamanders, population genetics, conservation, Texas Hill Country, Eurycea


Lucas, L. K. (2006). Population genetics and conservation of Texas Hill Country Eurycea (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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