Genetic Structure of Fagus sylvatica L. Populations in Southeastern Europe

Genetic structure of 38 populations from southeastern Europe has been studied using 11 enzymatic gene loci (PX-1, PX-2, GOT-1, 6-PGD-1, SOD-1 ACP-1, MDH-1, IDH-1, PGM-1, PGI-1 and MNR-1). Eight loci are polymorphic with gene diversity ranging from 0.179 to 0.461. Principal component analysis (PCA) based on allelic frequencies extracted 4 groups of populations: Rhodopes; Shars-Pindus range; Dinaric Alps and low Pannonic mountain ranges; Biokovo Mountain and Istrian Peninsula, well associated with geographical and climatic conditions. The statistical significance of this grouping was tested by discriminant analysis (DA). Although all 4 derived groups have high and similar values of the total diversity (respectively 0.250; 0.228; 0.282; 0.264), the share of loci which are more polymorphic varies from group to group. Presence of some rare alleles also indicates the difference between them. The correlations between estimated genetic differences and presumed occurrences during the glaciation and the postglaciation periods have been discussed, especially microgeographical conditions and evolutionary history of beechwoods from isolated regions of Biokovo and Istria. Multilocus F-statistics have also been computed. Positive FIT values for all groups of populations indicate some deficit of heterozygotes, while high F ST values prove certain differentiation among them.