Abstract
Progeny from 19 family lines of silver fir (Abies alba Mill.) from a small, native and isolated population from the Tisovik Reserve (Belarusian part of Białowieża Primeval Forest) growing in an experimental plot near Hajnówka (Polish part of Białowieża Primeval Forest) were analysed in terms of 4 nuclear microsatellite DNA loci and 9 isozyme systems with 14 loci. The aim of this study was to determine the genetic variation within and between progeny lines. Analysis of isozyme loci showed that all progeny lines, except the progeny lines T6 and T16, were characterised by an excess of heterozygotes and 20% of the detected variation occurred between progeny. Progeny formed two groups. Microsatellite loci showed that 6 progeny lines demonstrated an excess of heterozygotes and 12 an excess of homozygotes. On an average, the population was in the Hardy-Weinberg equilibrium. Analysis of molecular variance (AMOVA) showed that 14% of the detected variation occurred between offspring and the remaining 86% within progeny lines. The most distinct progeny line was Tl, where the highest number of alleles per locus was detected. Generally, progeny of Tisovik is characterised by high level of differentiation as the offspring of isolated population that have limited number of individuals to crossing (only 20). In some progeny line, the private alleles that are detected may be the result of pollination from Polish part of Białowieża Forest where in 1920s and 1930s of XX century had planted the seedling of silver fir of unknown origin. The substructuring of population is observed, and the detected deficiency of heterozygotes may be ostensible as a result of the Wahlund effect. Such pattern of genetic structure could also be an effect of harsh environmental conditions exerting selection pressure and modifying the genetic composition of this population.