Genetic diversity of southern populations of Abies alba Mill.

Genetic structure and diversity of 25 populations of Abies alba from Italy, Bulgaria, Macedonia and Romania was analyzed in 18 isozyme gene loci, and compared with reference populations from Central Europe (Czech Republic, Slovakia and Slovenia). The total of 56 alleles was identified in the loci surveyed, resulting in an average of 3.05 alleles per locus. The highest total number of alleles (47) and mean number of alleles per locus (2.6) was revealed in Calabria. Proportion of polymorphic loci ranged from 100 % in Calabria to 62.5 % in Bulgaria. The highest genetic multiplicity (GM) was detected in the Southern Carpathians, while the lowest one in Bulgaria. The polymorphisms at 10 loci including 23 alleles appeared to be area-specific. Southern populations of A. alba revealed mean observed heterozygosity (Ho) of 0.140 0.182, expected heterozygosity (He) 0.143-0.188, and effective number of alleles per locus (ni) 1.167-1.235. Corresponding parameters were lower in the Central-European populations (Ho = 0.101- 0.122, He = 0.102-0.124, ni = 1.114-1.142). A slight deficiency of heterozygotes was observed in all populations but there was no difference between vital southern and reference Central-European populations affected by the long-term dieback. The among-population component of total gene diversity accounted for 8.7 %, of which 5 % was between the southern and Central-European part of natural range, 2.9 % among provenance regions, and 0.8 % among populations within provenance regions. Southern provenance regions revealed higher gene diversity. Nei's unbiased genetic distances (Nei 1978) between the southern provenance regions ranged from 0.003 to 0.019. Genetic distances between the southern and Central-European regions were much higher, ranging from 0.019 to 0.037. According to their genetic structures and diversity, the southern populations of A. alba can be divided into 3 to 4 groups: (i) Bulgaria and Macedonia, (iii) Romanian Carpathians, and (iv) Calabria. Several area-specific alleles seem to be different between geographically adjacent Macedonia and Bulgaria, however.