Gene flow and population structure in Armeria maritima

Abstract

Gene flow distances and population structure were studied in populations of Armeria maritima (Mill). Willd. in Denmark. Gene flow was studied by direct methods using seed and pollen dispersal distances. Pollen flow in four experimental populations, where honey-bees were pollinators, surpassed the diameter of each experimental population. Seed dispersal was restricted and was used to partition a coastal grassland population into local populations. The structure of this population was analysed with a population genetic model that formulated a sequence of hypotheses about the action of natural selection and the geographical subdivision of the total population into local populations. The variation at a morphological marker locus was used for this purpose: the presence of hairs on the flower stalk in this species is determined by a dominant allele. The estimated pollen pools in the six local populations were homogeneous, and there was no evidence of deviation from random mating in any of the local populations. The genotypic distributions were homogeneous in the local populations and accorded with Hardy–Weinberg proportions. There was no evidence of selection at the studied locus, accordingly, the studied population was panmictic and its genotypic distribution could be described with a single parameter, the allele frequency at the marker locus.