Founder effects and the genetic structure of coulter pine

Abstract

Mean expected heterozygosity at 33 isozyme loci decreased with latitude from 0.193 near the southern extreme of Coulter pine's range to 0.107 at its northern extreme. This decrease was paralleled by a loss of alleles north of the Peninsular Ranges of southern California. Fiftenn alleles dropped out along the roughly linear range, at points coincident with large gaps in the species' disturbution. The pattern may reflect a cascading series of founder events as Coulter pine nvaded the Transverse Ranges and the South Coast Ranges from Pleistoncen refugia. Alleles were not replaced following colonization, probably because migration, Nm, among populations is only 0.74-1.27, depending on estimator, the lowest values reported in any pines. Wright's (F_ST) indicated that 16.5% of teh total genic diversity is among populations. The fixation index, (F_IS) of 0.072 indicated only a moderate excess of homozygotes.

Citation

Ledig, F. Thomas. 2000. Founder effects and the genetic structure of coulter pine. The American Genetic Association 91:307-315