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Testing Taxon Tenacity of Tortoises: evidence for a geographical selection gradient at a secondary contact zone

UA Open Access Publishing Fund / We examined a secondary contact zone between two species of desert tortoise,
Gopherus agassizii and G. morafkai. The taxa were isolated from a common ancestor
during the formation of the Colorado River (4–8 mya) and are a classic example
of allopatric speciation. However, an anomalous population of G. agassizii comes
into secondary contact with G. morafkai east of the Colorado River in the Black
Mountains of Arizona and provides an opportunity to examine reinforcement of
species’ boundaries under natural conditions. We sampled 234 tortoises representing
G. agassizii in California (n = 103), G. morafkai in Arizona (n = 78), and 53
individuals of undetermined assignment in the contact zone including and surrounding
the Black Mountains. We genotyped individuals for 25 STR loci and
determined maternal lineage using mtDNA sequence data. We performed multilocus
genetic clustering analyses and used multiple statistical methods to detect levels
of hybridization. We tested hypotheses about habitat use between G. agassizii and
G. morafkai in the region where they co-occur using habitat suitability models.
Gopherus agassizii and G. morafkai maintain independent taxonomic identities
likely due to ecological niche partitioning, and the maintenance of the hybrid zone
is best described by a geographical selection gradient model.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/621245
Date05 1900
CreatorsEdwards, Taylor, Berry, Kristin H., Inman, Richard D., Esque, Todd C., Nussear, Kenneth E., Jones, Cristina A., Culver, Melanie
ContributorsSchool of Natural Resources and the Environment, The University of Arizona, University of Arizona Genetics Core, University of Arizona, School of Natural Resources and the Environment; The University of Arizona; Tucson Arizona 85721, Western Ecological Research Center; U.S. Geological Survey; Falcon Business Park 21803 Cactus Avenue, Suite F Riverside California 92518, Western Ecological Research Center; U.S. Geological Survey; 160 North Stephanie St. Henderson Nevada 89074, Western Ecological Research Center; U.S. Geological Survey; 160 North Stephanie St. Henderson Nevada 89074, Western Ecological Research Center; U.S. Geological Survey; 160 North Stephanie St. Henderson Nevada 89074, School of Natural Resources and the Environment; The University of Arizona; Tucson Arizona 85721, School of Natural Resources and the Environment; The University of Arizona; Tucson Arizona 85721
PublisherWiley
Source SetsUniversity of Arizona
LanguageEnglish
Detected LanguageEnglish
TypeArticle
Rights©2015 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Relationhttp://doi.wiley.com/10.1002/ece3.1500

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