Abstract

Allozyme variability was assessed within and between 18 samples of four chromosomal races of the Liolaemus monticola complex: "Southern, 2n=34", "Northern, 2n=38-40", "Multiple Fission, 2n=42-44" and "Northern modified 1, 2n=38-40". This is an endemic montane Chilean lizard characterized by extensive chromosomal polytypy. The population genetic structure was studied by means of allozyme electrophoresis of 20 presumptive loci. Population heterogeneity analysis carried out by the estimation of Weir and Cockerham's F-statistic (θ), demonstrated substantial genetic differentiation among populations. The u-statistic, genetic distance data and multivariate analyses show that genetic variation is distributed into geographically coherent population groups in accordance with three of the four chromosome races. The greatest differentiation occurs between all populations of the "Southern, 2n=34" race and a second group that includes all populations from the "Northern, 2n=38-40" plus "Northern mod 1, 2n=38-40" races, separated from the "Multiple Fissions, 2n=42-44" race. As riverine barriers also separate these chromosomal races, we do not attribute the observed differentiation to isolation-by-distance or the chromosome characterization for each race. Possible routes of migration and colonization are proposed.