Population Structure of the Threatened Jollyville Plateau Salamander (Eurycea tonkawae): Implications for Conservation

The Jollyville Plateau salamander (Eurycea tonkawae) is a groundwater-dependent, neotenic species endemic to springs and caves of the karstic northern Edwards Aquifer in Central Texas. In 2013, this species was listed as threatened under the Endangered Species Act (ESA) due to groundwater depletion and rapid urbanization of the surrounding environments. Little is known about gene flow and population structure within this taxon despite the implications that genetic data may have for conservation and management of E. tonkawae populations. Here, we use previously published nuclear DNA and newly collected mitochondrial DNA sequence data to investigate population structure and divergence within E. tonkawae. Additionally, we use photographs to analyze morphological variation within the species. Our results identify two distinct genetic clusters (Eastern and Western) separated by surface and groundwater divides. These lineages may meet the criteria for Distinct Population Segment (DPS) designation under the ESA for conservation and management purposes.