Herpetological Conservation and Biology 5(1):189-195. Submitted: 19 May 2009; Accepted: 24 March 2010 189 GENETIC STRUCTURING OF GOPHER TORTOISE (GOPHERUS POLYPHEMUS) POPULATIONS ON THE KENNEDY SPACE CENTER, FLORIDA, USA COLLEEN S. SINCLAIR 1 , PATRICK J. DAWES, AND RICHARD A. SEIGEL Department of Biological Sciences, Towson University, 8000 York Road, Towson, Maryland 21229 1 corresponding author cwinters@towson.edu , Abstract.—Gopher Tortoises (Gopherus polyphemus) located on the Kennedy Space Center (KSC) in east-central Florida have been the subject of a long-term population study but little is known about the genetic structure of the population. Other studies across the species’ range have shown evidence that Gopher Tortoises have undergone population bottlenecks due to geographic isolation. We assessed the genetic diversity of Gopher Tortoises from five locations on KSC at six microsatellite loci in 96 individuals. Based on our analysis, the population does not subdivide into genetically distinct assemblages but appears to be one nearly continuous population (F ST = 0.030). This suggests that natural movement and/or human relocation has maintained the population’s gene flow across sites on the KSC. In terms of population genetics, we recommend that the tortoises on KSC be managed as a single population until further genetic analyses are completed. Key Words.—conservation; Gopherus polyphemus; Gopher Tortoise; management; population genetics INTRODUCTION Knowledge of the genetic structure of imperiled species may be essential to making informed management decisions (Allendorf and Luikart 2007; King 2009). This is especially true of populations with relatively limited ability for dispersal or for whom anthropogenic barriers such as roads may be difficult to cross. Population isolation can lead to a loss of genetic variation through the alteration of gene frequencies (Noss et al. 2006). On a larger scale a severe reduction in genetic variation can reduce a population’s capacity to adapt to changing environmental conditions, make the individuals more susceptible to disease and in turn lead to disruption of the ecosystem (King 2009). Therefore, preservation of genetic variation in an imperiled species should be a priority of any management plan. Gopher Tortoises (Gopherus polyphemus) are one of four native tortoise species in the United States and the only species found east of the Mississippi River (Ernst et al. 1994). Widely considered a keystone species in Florida and the southern reaches of Mississippi, Alabama, Georgia, South Carolina, and Louisiana (Auffenberg and Franz 1982; Kushlan and Mazzotti 1984; Diemer 1986, 1992; Breininger et al. 1994), they are threatened by habitat loss due to increased urban land use, agriculture, and phosphate/heavy metals mining (Auffenberg and Franz 1982; McCoy and Mushinsky 2005; Berish 2001). Gopher Tortoises in Florida experienced an 88% decline in longleaf pine forest habitat between 1936 and 1987 (Noss 1989; Kautz 1993). As a result of these threats, it is estimated that tortoise populations have declined by more than 80% since the 1880’s (Auffenberg and Franz 1982). With the rapid decline of suitable habitat due to increased construction and agriculture throughout the southeastern United States, Gopher Tortoises are protected at the international, federal, and state level. Gopherus polyphemus is listed as an Appendix II species under the Convention on International Trade in Endangered Species (Ipskipp and Gillett 2003) and tortoises west of the Tombigbee and Mobile Rivers are listed as threatened by the Endangered Species Act (U.S. Fish and Wildlife 1986). At the state level, Gopher Tortoises are listed as threatened in Georgia, Florida, and Louisiana, endangered in South Carolina and Mississippi, and protected as a non-game species in Alabama, USA. In an attempt to protect tortoises in the pathway of construction, many individuals are relocated to new habitats. In Florida alone, > 25,000 tortoises were permitted for relocation in the 1990’s (Enge et al. 2002). The actual number of relocations is probably much higher when considering the number of unpermitted relocations. However, until recently, the relocations were made with little or no regard to the genotype of the tortoises and the possible genetic impact on the population at their new home site. Schwartz and Karl (2005) used microsatellites to assess the genetic diversity of 300 Gopher Tortoises from locations across Florida and southern Georgia. They identified eight genetic subpopulations and evidence that several groups had undergone population bottlenecks due to isolation. Genetic variation in four groups from the Middle Florida