Tracing Genetic Lineages of Captive Desert Tortoises in Arizona (Via HerpDigest)

Tracing Genetic Lineages of Captive Desert Tortoises in Arizona

Journal of Wildlife Management
Volume 74, Issue 4 (May 2010): pp. 801-807

Taylor Edwards1,a, Christopher J. Jarchowa, Cristina A. Jones2,b, and Kevin E. Bonineb
a Arizona Research Laboratories, Human Origins Genotyping Laboratory, University of Arizona, Tucson, AZ 85721, USA
b School of Natural Resources, University of Arizona, 325 Biological Sciences East, Tucson, AZ 85721, USA

We genotyped 180 captive desert tortoises (Gopherus agassizii) from Kingman (n = 45), Phoenix (n = 113), and Tucson (n = 22), Arizona, USA, to determine if the genetic lineage of captives is associated with that of wild tortoises in the local area (Sonoran Desert). We tested all samples for 16 short tandem repeats and sequenced 1,109 base pairs of mitochondrial DNA (mtDNA). To determine genetic origin, we performed assignment tests against a reference database of 997 desert tortoise samples collected throughout the Mojave and Sonoran Deserts. We found that >40% of our Arizona captive samples were genetically of Mojave Desert or hybrid origin, with the percentage of individuals exhibiting the Mojave genotype increasing as the sample locations approached the California, USA, border. In Phoenix, 11.5% were Sonoran-Mojave crosses, and 8.8% were hybrids between desert tortoise and Texas tortoise (G. berlandieri). Our findings present many potential implications for wild tortoises in the Sonoran Desert of Arizona. Escaped or released captive tortoises with Mojave or hybrid genotypes have the potential to affect the genetic composition of Sonoran wild populations. Genotyping captive desert tortoises could be used to inform the adoption process, and thereby provide additional protection to native desert-tortoise populations in Arizona.

Keywords: Arizona, captivity, genetic assignment, Gopherus agassizii, Gopherus berlandieri, Mexico, Mojave Desert, mitochondrial DNA (mtDNA), short tandem repeat (STR), Sonoran Desert
DOI: 10.2193/2009-199
Associate Editor: Latch.
1 E-mail: taylore@email.arizona.edu
2 Present address: Arizona Game & Fish Department, Nongame Branch, Phoenix, AZ 85086, USA