Genetic differentiation and phylogeny of beech on the Balkan peninsula

Genetic differentiation of 57 beech populations originating from a wide geo graphical space from the foothills of the Eastern Alps over the Balkan peni nsula was investigated employing isozyme markers. Pooled datasets of Europe an beech populations originating from four adjacent regions and Eastern bee ch populations originating from Thrace and Western Asia Minor were compared . Considerable differences of allele frequencies among regions were found i n several marker loci. The highest level of genetic multiplicity and differ entiation was found in the populations from the southern Balkans; however, the north-western populations showed higher genetic diversity. The pattern of genetic differentiation based on multilocus genetic distances is a clina l one. The populations belonging to the putative taxon Fagus moesiaca Czecz ott seem to form an independent group. Three hypotheses of the evolutionary , origin of this taxon are discussed: selection, introgressive hybridizatio n and continuous evolution.