Floral and genetic divergence across environmental gradients is moderated by inter-population gene flow in Platanthera dilatata (Orchidaceae)

Understanding how natural selection acts on intraspecific variation to bring about phenotypic divergence is critical understanding processes of evolutionary diversification. The orchid family well known for pollinator-mediated floral phenotypes operating among species and along environmental or geographic gradients. Its effectiveness at small spatial scales less understood, making the scale which examined important evaluating causes divergence. In this study, we quantified in Platanthera dilatata across 26 populations coastal Southeast Alaska compared edaphic genetic microsatellite loci. We sought determine (1) if flower morphological structured smaller scales, (2) extent relation divergence, (3) inter-population gene flow occurs, (4) relative importance distance abiotic factors population structure. Two groups were found separate based lip spur length are restricted different habitats. Small-flowered forms occur muskeg bogs, whereas large-flowered fens meadows, rarely sub-alpine habitat. Genetic analyses concordant with clusters, except four small-flowered that genetically indistinguishable from considered be introgressed. fact, most exhibited some admixture, indicating incomplete reproductive isolation between forms. Pollinators may partition but also facilitate because short-tongued Noctuidae moths pollinate both phenotypes, longer-tongued hawkmoths only observed pollinating phenotype, strengthen Nevertheless, pollinator movement habitats could have lasting effects neutral variation. At scale, structure associated distance, likely due extensive seed movement. While study corroborates previous findings cryptic lineages P. , examination provided greater underlie