Large-scale patterns of genetic variation among indigenous populations of Abies alba and Fagus sylvatica L.

Paule L. ¹, Gömöry D. ¹, Longauer R.² and D. Krajmerová¹

¹ Technical University in Zvolen, Faculty of Forestry, T.G. Masaryka 24, SK-960 53 Zvolen, Slovakia

² National Forest Centre, Forest Research Institute, T.G. Masaryka 22, SK-960 92 Zvolen, Slovakia
paule@vsld.tuzvo; gomory@vsld.tuzvo.sk; longauer@fris.sk; krajmer@vsld.tuzvo.sk

This contribution summarizes research on genetic differentiation and diversity of populations of two forest tree species, which are principal constituents of montane and subalpine forest belts in Europe and western Asia: silver fir (Abies alba Mill.), and beech (Fagus sylvatica L.), employing isozyme gene markers. Additionally, the genetic footprints of the postglacial recolonization processes are briefly discussed. In beech, a strong differentiation both within and among regional groups of populations was observed. This applies mainly to oriental beech (F. sylvatica ssp. orientalis), where many populations were not affected by the Pleistocene glaciations and have persisted on their sites since the Tertiary. In contrast, beech populations in Europe (F. sylvatica ssp. sylvatica) are genetically much more homogeneous, indicating that most populations (except those on the Apennine peninsula) originate from the same glacial refugium, situated in the eastern foothill of the Alps (Slovenia). In Europe allelic richness within populations generally decreases towards the northern margin of the range, indicating a gradual loss of alleles through repeated founder events during the postglacial colonization. Silver fir showed a strong differentiation among regions and a clear geographic pattern. Allelic frequencies and gene diversity exhibited a clinal variation along the Carpathian ridge. The Western Carpathians had the lowest levels of genetic diversity. Genetic diversity within populations subsequently increased both to the West (Herzynic and Pre-Alpine region) and South-East (Eastern and Southern Carpathians, Balkans). In contrast to diversity, allelic richness was quite regularly distributed. A study based on mtDNA (PCR-RFLP) markers showed that in contrast to beech with leptokurtic seed dispersal, leading to patchy distribution of haplotypes, the migration front of fir during the postglacial colonization remained rather compact, leading to a sharp boundary between haplotypes within the suture zones.

Keywords: Abies alba, Fagus sylvatica, genetic diversity, allelic richness, Carpathians