Genetic differentiation and linkage disequilibrium in a spatially fragmented population of Cheilosia vernalis (Diptera: Syrphidae) from the Balkan peninsula

Abstract

Multi-locus allozyme associations and genetic differentiation in a spatially fragmented population of Cheilosia vemalis were analyzed based on the allelic frequencies at nine polymorphic allozyme loci. Standardized variance of allelic frequencies indicated that the spatially separate subpopulations from three different biogeographical regions on the Balkan Peninsula were a part of a structured metapopulation, with a moderately to greatly differentiated gene pool. Pairwise genetic differentiation was correlated with genetic distance between pairs of subpopulations, and both increased with increasing geographic distance. The percent of polymorphic loci pairs with significant non-random associations among alleles ranged from 33% to 50% within subpopulations. The proportion of loci pairs with non-random allelic associations was higher on the level of the total pooled population (64% for total pooled). The subdivision among the geographically separated subpopulations was analyzed by applying Ohta's method of partitioning the total variance of linkage disequilibrium. Variance components indicated that subdivided population structure coupled with limited migration, which reduced the chance of generating recombinant gametes, might be responsible for observed linkage disequilibrium.