Genetic variability of pedunculate oak (Quercus robur L.) in the left-bankpart of the Mari El Republic

Based on isozyme analysis at 12 loci, genetic variability of four natural p opulations of pedunculate oak Quercus robur L,. spread inhabiting the left- bank part of the Republic of Mari E1 was studied. High variability of pedun culate oak populations was shown: 75% of genes were in a polymorphic state, the average number of alleles per locus was 2.4-2.5. The observed and expe cted heterozygosities varied from 16.1% to 17.8% and from 16.2-18.4%, respe ctively. This is higher than the genetic variation in oak populations of Fi nland, but considerably lower than in populations of Germany and France (ec ological optimum of oak). The populations share a common gene pool with int ensive gene exchange between populations. Nei's genetic distances varied fr om 0.0016 to 0.0065, and G(st) was 0.013.