Distribution of genetic variation within and among Danish populations of Armeria maritima, with special reference to the effects of population size

Abstract

Genetic variation encoded by five isozyme loci was investigated in 17 populations of Armeria maritima in Denmark. A. maritima maintains most of its isozymic variation within populations and it is concluded that gene dispersal within populations is relatively high since random union of gametes was found in all populations. From the level of differentiation between populations, an estimate of gene Bow was obtained. This intermediate level of gene flow is not sufficient to keep the investigated populations together in geographical clusters, in spite of the Fact that the species is very common and widespread, and that dispersal corridors, in the form of roadside verges, are abundant. A comparison of plant diameter, which is a measure of plant age, and individual heterozygosity revealed no correlation between these two variables. The size of populations was found to be significantly correlated with the level of isozymic variation, measured as H,, mean number of alleles and number of polymorphic loci. In addition, the small populations showed a higher genetic differentiation (F(st) = 0.30) than the larger populations (F(st) = 0.17).