GENETIC-STRUCTURE OF ENGLISH YEW (TAXUS-BACCATA L)IN THE WIERZCHLAS RESERVE - IMPLICATIONS FOR GENETIC CONSERVATION

Genetic structure and mating patterns were studied in Taxus baccata L. in the Wierzchlas Reserve in Poland, using 18 allozyme loci as geneti c markers. The population exhibited high levels of genetic variation, with expected heterozygosity estimated for all loci equal to 0.279. Th e effective number of alleles was 1.37, and 61.11% of loci were polymo rphic. Expected heterozygosity calculated for polymorphic loci only wa s as large as 0.419. The level of inbreeding as measured by Wright's f ixation index was generally low for parental trees. However, in progen y population an excess of homozygotes was observed compared with the H ardy-Weinberg equilibrium (F= + 0.049), which may be attributed to mat ing between relatives (biparental inbreeding). The effective populatio n size calculated for both male and female trees was considerable and accounted for about 56 individuals. Allele frequencies in the pollen p ool successful in fertilizing viable embryos were, in general, spatial ly homogeneous across the sampled trees. Considering the high genetic diversity and relatively large population size, the Wierzchlas Reserve represents a valuable gene pool for reforestation of Taxus baccata.