Genetic structure of a montane perennial plant: the influence of landscape and flowering phenology

The way that genetic variation is distributed geographically has important conservation and evolutionary implications. Here, we examined the distribution of genetic variation within and among populations of the montane perennial Ipomopsis aggregata. We sampled plants in western Colorado and examined (1) population genetic structure over a geographic area that spanned 130 km, including genetic variation within disturbed and undisturbed sites; (2) the relationship between genetic differentiation and geographic distance; and (3) the relationship between flowering time and genetic differentiation among plants within and among geographic areas. F IS was significantly higher (t test, P = 0.006), expected heterozygosity was significantly lower (t test, P = 0.04), and allelic richness was marginally significantly lower (t test, P = 0.078) among anthropogenically-disturbed sites compared to undisturbed sites. We found moderate genetic differentiation over the area sampled (average pairwise F ST = 0.04; average pairwise [Formula: see text]), but no association of genetic and geographic distance (Mantel test P values 0.44 for F ST and 0.36 for [Formula: see text]). We found a strong association of flowering time and genetic differentiation over small and large spatial scales. Genetic differentiation between early and late flowering plants within a focal site was statistically significant (genic test for population differentiation combined P value