Cooperative Fish and Wildlife Research Units Program: Arizona
Education, Research and Technical Assistance for Managing Our Natural Resources

Goal: To define the phylogeographic units for the desert tortoise in the presence of a secondary contact zone between Mojave and Sonoran populations, and between Sonoran and Sinaloan populations. We hypothesize that there are 3 lineages of the desert tortoise, Gopherus agassizii (Sonoran, Mojave, and Sinaloan) and that gene trees within each lineage will be in concordance. This hypothesis will be tested by employing a multilocus approach and reconstructing gene trees for several independently inherited markers representing multiple regions of the genome. A second hypothesis is that ecotones form the boundaries among the 3 lineages of desert tortoises. This will be tested by assessing whether the distributions of gene trees correlate with the geographic distribution of vegetative communities. We hypothesize that we will not find naturally occurring introgression among genetic lineages. We will test this hypothesis by identifying if hybrid individuals exist beyond the F1 generation. Lastly, we will look for evidence of additional speciation among lineages in Mexico.