Meeting Abstract
P2.112 Tuesday, Jan. 5 Genetic Differentiation, Range Expansion, and Loss of Allelic Diversity Within the Western Fence Lizard (Sceloporus occidentalis) in the Basin and Range Province ARCHIE, James W*; THOMPSON, Milinda; California State Univ., Long Beach; California State Univ., Long Beach jarchie@csulb.edu
The western fence lizard is distributed throughout the Basin and Range Province of western North America (800km X 500km) at intermediate elevations in isolated and semi-isolated mountain ranges. Based on a phylogenetic analysis of mtDNA variation, four distinct clades are present with > 5% sequence divergence between them. Two of these clades (central and western) exhibit extremely low levels of variability, consistent with a post-Pleistocene range expansion. Based on the degree of mtDNA differentiation within and between the clades, we predicted significant nuclear genetic differentiation between clades and a loss of allelic diversity progressing from south to north in two of them. We analyzed the geographical distribution of mtDNA clade variants using clade specific RFLP patterns and patterns of nuclear genetic differentiation and diversity using six microsatellite loci in populations sampled throughout the region. Overlap of mtDNA clades in the region was minimal; only isolated intergrade populations were found. Contrary to our hypothesis, we found a lack of genetic differentiation at microsatellite loci between adjacent mtDNA clades consistent with high levels of gene flow. However, we found significant genetic variation as follows: 1) southern clade populations were differentiated from others clades, 2) an isolation by distance effect within central and western clades (but not the others), and 3) a loss of allelic diversity from south to north in the central and western clades. The results support the hypothesis of northward range expansion of within two clades associated with post-Pleistocene climate changes. These are consistent with low levels of mtDNA variation found within the Central and Western clades, but not the Eastern or Southern.
