Phylogeography of a wide-ranging desert lizard, Gambelia wislizenii (Crotaphytidae)

Intraspecific phylogeography of the long-nosed leopard lizard (Gambelia wis lizenii) was examined using 419 base pairs of sequence of the mitochondrial ly encoded COIII gene from 23 individuals sampled from populations represen ting five regional deserts in western North America. Intraspecific populati on structure was evaluated under two biogeographic models: (1) gene flow am ong populations during late Pleistocene to Recent times, possibly in conjun ction with range expansions from Pleistocene refugia; or (2) subdivision am ong southwestern desert regions that occurred in conjunction with late Plio cene/early Pleistocene geological events or as a result of isolation in sep arate Pleistocene refugia. Phylogenetic analysis indicated subdivision of 1 8 mitochondrial DNA haplotypes into two major clades separated by approxima tely 6.1% sequence divergence: Western (Mojave + Great Basin + Colorado Pla teau deserts) and Eastern (Chihuahuan desert). A third, more divergent, lin eage with unknown geographic distribution was represented by a single haplo type from southwestern Arizona. The Western clade contained two northern Gr eat Basin subclusters (eastern Great Basin and western Great Basin), repres enting populations separated from one another by approximately 5.4% sequenc e divergence. These phylogeographic breaks are consistent with the second m odel of late Pliocene/early Pleistocene vicariance. These data are also con sistent with assessments of the biogeographic histories of several other ar id-dwelling vertebrates.