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Conservation Genetics

, Volume 11, Issue 5, pp 1795–1807 | Cite as

Defining population structure for the Mojave desert tortoise

  • Bridgette E. Hagerty
  • C. Richard Tracy
Research Article

Abstract

We used highly variable microsatellite markers to identify population structure, movement, and biological boundaries for populations of the desert tortoise, Gopherus agassizii, in the Mojave and Colorado Deserts of the southwestern United States. The Mojave desert tortoise (listed as “threatened” by the U.S. Fish and Wildlife Service) has a large geographic range, long generation time, low population densities, and little above-ground activity. Additionally, the dispersal patterns of individual tortoises are virtually unknown, making indirect methods to assess movement among populations valuable. Using Bayesian assignment tests, we detected hierarchical structuring within the Mojave desert tortoise. Three basal groups were identified, and these corresponded to the mitochondrial DNA haplotypes reported in 1989. Additional population structure was evident within each basal unit, and this structure corresponds with major geographic barriers. Our analyses suggest that gene flow among populations was historically high because levels of population differentiation were low across the range. Geographic distance explained a large proportion of variation in genetic distance (68%), which pinpoints that dispersal is limited only on a regional scale. In light of these new analyses of the genetic population structure of the Mojave desert tortoise, we make new recommendations for the number and locations of recovery units for conservation of this species.

Keywords

Desert tortoise Gopherus agassizii Population structure Microsatellites Mojave Desert Conservation unit 

Notes

Acknowledgements

The Clark County Multi-Species Habitat Conservation Plan and the U.S. Fish and Wildlife Service supported this research. Sample collection was permitted by the USFWS (TE-076710), NDOW (S 24403), CADFG (SC-007374), and UDWR (5BAND6646). All procedures were performed with the approval of the IACUC at UNR (protocol # A03/04-12, A05/06-23). We thank F. Sandmeier and technicians from the University of Nevada, Reno, Student Conservation Association, and Kiva Biological for helping with sample collection. We thank V. Kirchoff and the Nevada Genomics Center (NIH Grant P20 RR016463)) for helping to genotype individuals. We also thank G. Hoelzer, M. Peacock, L. Zimmerman, the UNR graduate student peer review group, and two anonymous reviewers for helpful comments on this manuscript.

Supplementary material

10592_2010_73_MOESM1_ESM.doc (110 kb)
(DOC 110 kb)

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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.Program in Ecology, Evolution, and Conservation BiologyUniversity of Nevada, RenoRenoUSA
  2. 2.Department of Biology, MS/315University of Nevada, RenoRenoUSA

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