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

Sevan S. Suni, Andrew R. Whiteley

    Research output: Contribution to journalArticlepeer-review

    Abstract

    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. FIS 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 FST = 0.04; average pairwise F′ST=0.19), but no association of genetic and geographic distance (Mantel test P values 0.44 for FST and 0.36 for F′ST). 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 <0.001; FST = 0.05). There was a significant correlation between genetic distance (F′ST) and distance in flowering time, when controlling for geographic distance, over the whole geographic area (Partial Mantel test Rxy = 0.32, P = 0.013). A multiple regression with randomization further supported the inference that flowering time, but not geographic distance or elevation, predicted F′ST (geographic distance: β = −0.03, P = 0.89; elevation: β = 0.01, P = 0.96; phenological distance: β = 0.30, P = 0.05), but not Fst (geographic distance: β = −0.02, P = 0.92; elevation: β = 0.14, P = 0.38; phenological distance: β = 0.25, P = 0.11), unless elevation was left out of the model (geographic distance: β = −0.03, P = 0.9; phenological distance: β = 0.29, P = 0.03). The association of flowering time and genetic distance despite the lack of isolation by distance provides further evidence for the usefulness of incorporating this variable into plant landscape genetic studies when possible.

    Original languageEnglish
    Pages (from-to)1431-1442
    Number of pages12
    JournalConservation Genetics
    Volume16
    Issue number6
    DOIs
    StatePublished - Dec 1 2015

    Keywords

    • Flowering time
    • Genetic differentiation
    • Genetic structure
    • Ipomopsis aggregata
    • Phenology

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