Distribution, abundance, and population genetics of the alligator snapping turtle (Macrochelys temminckii) in Mississippi

The southeastern United States is a freshwater turtle biodiversity hotspot, second only to southeastern Asia, and this region is inhabited by one of the largest freshwater turtles in the world: the alligator snapping turtle (Macrochelys temminckii). This species was heavily harvested from the 1960’s to the 1980’s for the turtle soup industry, apparently contributing to substantial, range-wide population declines. These declines, coupled with anthropogenic impacts on riverine and floodplain habitats, have led to M. temminckii being petitioned for federal listing under the U.S. Endangered Species Act; it is currently under review by the U.S. Fish and Wildlife Service to determine if listing is warranted. Up-to-date information on the distribution, abundance, and genetic diversity is necessary to accurately assess the conservation status of a species. However, despite having a presumed statewide distribution in Mississippi, there was a paucity of records for M. temminckii in the state, thus leaving a gap in our knowledge about the core of this species’ geographic range. Therefore, my primary objective was to determine the distribution and abundance of M. temminckii in all major river systems of the state: the Pascagoula, Pearl, Tombigbee, and Mississippi River drainages. Additionally, the lack of genetic information about M. temminckii in Mississippi was evident in previous range-wide genetic assessments. My secondary objectives were to fill this knowledge gap by 1) determining if M. temminckii populations in Mississippi followed a similar pattern of genetically discrete populations inhabiting geographically isolated river drainages and 2) to assess genetic diversity indices, historical bottlenecks, and within drainage population structure. This up-to-date information from the core of M. temminckii’s geographic distribution can be used to plan and implement future management and conservation strategies to preserve an iconic, southeastern turtle species