Articles Range-Wide and Regional Patterns of Population Structure and Genetic Diversity in the Gopher Tortoise D. Gaillard, J.R. Ennen, B.R. Kreiser,* C.P. Qualls, S.C. Sweat, R. Birkhead, T.D. Tuberville, M. Aresco, E.D. McCoy, H.R. Mushinsky, T.W. Hentges D. Gaillard, B. Kreiser, C. Qualls Department of Biological Sciences, University of Southern Mississippi, Hattiesburg, Mississippi 39406 Present address of D. Gaillard: School of Life Sciences, Peking University, Beijing 100871, China J. Ennen, S. Sweat Tennessee Aquarium Conservation Institute, Chattanooga, Tennessee 37405 R. Birkhead COSAM Outreach, Alabama Science in Motion, Auburn University, Auburn, Alabama 36849 T.D. Tuberville Savannah River Ecology Lab, University of Georgia, Drawer E, Aiken, South Carolina 29802 M. Aresco Nokuse Plantation, 13292 County Highway 3280, Bruce, Florida 32455 E.D. McCoy, H.R. Mushinsky, T. Hentges Integrative Biology, University of South Florida, Tampa, Florida 33620 Abstract The gopher tortoise (Gopherus polyphemus) has experienced dramatic population declines throughout its distribution in the southeastern United States and is federally listed as threatened in the area west of the Tombigbee and Mobile rivers. While there is molecular support for recognizing the listed portion of the range as genetically distinct, other research has suggested that additional population structure exists at both range-wide and regional scales. In this study, we sought to comprehensively define genetic population structure at both spatial scales by doubling the data available in terms of the number of sampling sites, individuals, and microsatellite loci compared to previously published work. We also compared patterns of genetic diversity, gene flow, and demographic history across the range. We collected 933 individuals from 47 sampling sites across the range and genotyped them for 20 microsatellite loci. Our range-wide analyses supported the recognition of five genetic groups (or regions) delineated by the Tombigbee and Mobile rivers, Apalachicola and Chattahoochee rivers, and the transitional areas between several physiographic province sections of the Coastal Plains (i.e., Eastern Gulf, Sea Island, and Floridian). We found genetic admixture at sampling sites along the boundaries of these genetically defined groups. We detected some degree of additional genetic structure within each of the five regions. Notably, within the range listed as threatened under the Endangered Species Act, we found some support for two additional genetic groups loosely delineated by the Pascagoula and Chickasawhay rivers, and we detected four more genetic groups within the Florida region that seemed to reflect the influence of the local physiography. Additionally, our range-wide analysis found the periphery of the range had lower levels of genetic diversity relative to the core. We suggest that the five main genetic groups delineated in our study warrant recognition as management units in terms of conservation planning. Intraregional population structure also points to the potential importance of other barriers to gene flow at finer spatial scales, although additional work is needed to better delineate these genetic groups. Keywords: conservation genetics; management units; phylogeography; southeastern United States Received: February 2, 2017; Accepted: July 24, 2017; Published Online Early: August 2017; Published: December 2017 Citation: Gaillard D, Ennen JR, Kreiser BR, Qualls CP, Sweat SC, Birkhead R, Tuberville TD, Aresco M, McCoy ED, Mushinsky, HR, Hentges TW. 2017. Range-wide and regional patterns of population structure and genetic diversity in the gopher tortoise. Journal of Fish and Wildlife Management 8(2):497–512; e1944-687X. doi:10.3996/022017-JFWM-010 Journal of Fish and Wildlife Management | www.fwspubs.org December 2017 | Volume 8 | Issue 2 | 497 Downloaded from http://meridian.allenpress.com/jfwm/article-pdf/8/2/497/2338334/022017-jfwm-010.pdf by guest on 10 October 2023