Advanced Topics in Conservation Genetics Webinar Series

Advanced Topics in Conservation Genetics

These webinars provide biologist and managers with the latest techniques in conservation genetics.

This webinar series is for educational purposes only. The opinions, ideas or data presented in this webinar series do not represent FWS policy or constitute endorsement by FWS. Some of the materials and images may be protected by copyright or may have been licenses to us by a third party and are restricted in their use.  Mention of any product names, companies, Web links, textbooks, or other references does not imply Federal endorsement.


June - November 2014


Date: Tuesday, September 16th, 2014
Time: 2:00-3:00 PM ET
Topic: Are Captive Tortoises a Reservoir for Conservation?
Captioning: Captioning services will be available for this webinar.
Archive: If you are unable to attend this webinar, it will be recorded and posted to the Advanced Topics in Conservation Genetics Webinar Series Archive approximately 1-2 weeks after the presentation.
Presenter: Taylor Edwards, University of Arizona
Description: The conservation of tortoises poses a unique situation because several threatened species are commonly kept as pets within their native range.Desert Tortoise.  Photo by USFWS Thus, there is potential for captive populations to be a reservoir for repatriation efforts. As a result of ongoing evolutionary studies on desert tortoises (Gopherus agassizii and G. morafkai) we have assembled a massive genotypic database of 1258 Gopherus samples, spanning the full range of both species in the Mojave and Sonoran deserts plus other congeners. Here, we present the results of two studies where we genotyped captive (pet) tortoises at STR and mitochondrial loci to determine their geographic origins. We performed assignment tests to assess the utility of captive populations for recovery efforts based on genetic affinity to local areas. For G. morafkai in Arizona, we genotyped 180 captive desert tortoises from Kingman (n = 45), Phoenix (n = 113), and Tucson (n = 22), Arizona. We found that >40% of our Arizona captive samples were genetically G. agassizii or hybrid origin. For G. agassizii, we collected samples from 130 captive desert tortoises from three desert communities: two in California (Ridgecrest and Joshua Tree) and the Desert Tortoise Conservation Center (Las Vegas) in Nevada. For our total sample set, only 44% of captive individuals were assigned to local populations based on genetic units derived from the reference database. Our data suggest that captive desert tortoises kept within the native range of both G. agassizii and G. morafkai cannot be presumed to have a genealogical affiliation to wild tortoises in their geographic proximity. Escaped or released captive tortoises have the potential to affect the genetic composition of native populations. Genotyping captive desert tortoises could be used to inform the adoption process, and thereby provide additional protection to native desert tortoise populations. Precautions should be taken before considering the release of captive tortoises into the wild as a management tool for recovery.


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Marilyn Williams, Training Technician, Conservation Science and Policy Branch, National Conservation Training Center at 304-876-7940; e-mail


Matthew Patterson, Course Leader, Conservation Science and Policy Branch, National Conservation Training Center at 304-876-7473; e-mail