Conservation genetics, evolution and distinct population segments of the Mojave fringe-toed lizard, Uma scoparia

Abstract

Mojave fringe-toed lizards, Uma scoparia, occur only on desert sand dunes and associated mosaics of small sand ramps. Consequently, the distribution is naturally discontinuous and geographically complex. Many populations are vulnerable to local extirpation, and some are now gone. We synthesized genealogical and paleoecological data to explain the geographic relationships among populations of U. scoparia based on mitochondrial DNA sequence data. The species appears to have arisen from a common ancestor with U. notata by a vicariance event, associated with the formation and development of the Lower Colorado River. Within U. scoparia, two major maternal lineages are associated with the development of river drainage systems. The northern lineage is from the Amargosa River. The southerly lineage includes the Mojave River basin, Bristol Trough, Clark's Pass, and Colorado River sand transport systems. The northernmost lineage of U. scoparia, isolated in the vicinity of Plio-Pleistocene Lake Tecopa, has the greatest amount of DNA sequence divergence. The southern populations exhibit little local genetic differentiation. A small population near Red Pass Lake contains haplotypes from both the northern and southern lineages. We define two distinct population segments (DPSs), one associated with the Amargosa River lineage, and the other with Red Pass Dune.