Relationship between sample size and genetic diversity in oriental beech (Fagus orientalis Lipsky)

Sample size is a critical issue for genetic diversity studies and conservation programs. However, sample size evaluation requires previous knowledge of genetic diversity. Here, we evaluated sample size requirements for accurate genetic diversity in adult trees and family arrays in a Fagus orientalis Lipsky population in central Hyrcanian forests ofIran. Data consisted of 350 adult trees and 480 offspring's from 60 mother tree genotyped at four nuclear microsatellites. Results indicated that several adult individuals (about 300) are necessary for accurate measures of allele richness. However, expected heterozygosity requires smaller samples (30). Seeds from 50 trees captured about 90% of adult allelic diversity suggesting that seed sampling is heavily finalized for allele counts, and this should be considered in conservation programs. Nevertheless, gene diversity of seeds was lower than that of the adult population, which emphasizes on conservation of natural stands and in situ conservation programs. Extrapolation of these results to other tree species with similar distribution (widespread), way of propagation (wind-pollinated, dispersion of the fruits by gravity), density (about 200-400 individuals in ha), and genetic structure as oriental beech could be possible.