Date of Award

Spring 5-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Committee Chair

Brian Kreiser

Committee Chair Department

Biological Sciences

Committee Member 2

Carl Qualls

Committee Member 2 Department

Biological Sciences

Committee Member 3

Joshua Ennen

Committee Member 4

Michael Davis

Abstract

The gopher tortoise, Gopherus polyphemus, is an endangered species living in the southeastern United States. The recent and drastic decline in tortoise numbers has resulted in a multi-faceted approach to conserve this species. I used a population genetic approach to determine the population structure, genetic diversity and barriers to gene flow at a broad, regional and local scale. Tortoises are divided into five distinct genetic populations at the broad scale, the central populations have the highest levels of genetic diversity and the Tombigbee, Mobile, Apalachicola, Suwannee and St. John’s Rivers appear to be barriers to gene flow. At the regional scale, the Pascagoula River splits tortoises into two populations within the listed range and the Florida Ridge System plays a role in shaping the genetic structure of tortoises within peninsular Florida. Significant but weak genetic structure was detected at the local scale across the Ft. Benning landscape and there did not appear to be any landscape features contributing to population genetic structure. In addition to population genetics, microbial and plant communities of the gopher tortoise were tested for differences and associations between geographic localities, as these might be important factors for the success of translocated tortoises. Microbial communities did not show a correlation between community dissimilarity and geographic distance nor did they change in response to changes in plant communities at each site. Gut and soil microbial communities differed significantly from each other suggesting that soil microbes may play a small role in gut inoculation. Considering the genetic structure of gopher tortoises is important when planning management strategies, whereas, microbial communities might not be strongly impacted due to the translocating of tortoises.

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