Distribution of allozyme variation in Siberian Stone pine at individual, within (ecological) and between (geographical) populations levels is considered. Main goal of the study is to analyze a factors affecting distribution of genetic diversity at the different levels of organization. We studied Siberian Stone Pine even-aged plantations, natural populations (forest-bog ecological transect locates in the southern subzone of taiga in West Siberia; altitudinal transect locates in North-Eastern Altai), and clonal archive. Genotypes of 1014 model trees and clones were determined by no less than 21 isozyme loci using starch gel electrophoresis.

To reveal a distribution of genetic diversity at individual level we test hypotheses on isozyme heterozygosity of genome determined a rate of sexual maturation and life longevity of species (Altukhov, 1998). In even-aged Siberian Stone pine plantations the virgin trees without cones have been shown to be less heterozygous for isozyme loci and significant negative relation between the sexual reproduction start age and heterozygosity was shown in cone bearing trees. The relation was stronger in higher density stand because of phytocenotic stress due to intraspecies competition. In long-lived natural Siberian Stone pine population located near bogged ecological distribution limit significant negative correlation between age and allozyme heterozygosity was find in older (more than 350 years old) trees group. Presumably it account for slow ontogenetic growth rate of the less heterozygous trees and moderate competition in the low density forest stand.

Within population distribution of genetic polymorphism was studied in two natural P. sibirica populations comprised of a series of consecutive sites along limiting factors from normal to unfavorable environments. Two factors affecting distribution of gene diversity were considered – natural selection and gene flow by nutcracker seed dissemination. Internal genetic substructure of studied populations associates with combination of main environmental factors such as soil moisture and fertility at forest-bog transect and air temperature at altitudinal transect. The findings attest that allozyme polymorphism can be partly involved in adaptation of Siberian stone pine to survival at marginal environments.

Distribution of allozyme variation along latitudinal and longitudinal transects was explored based upon 11 ecotypes representing all the main forest site types of Siberian Stone pine range. According to our data allele frequencies on some isozyme loci correlated significantly with latitude and longitude of ecotypes and genetic subdivision of ecotypes was higher on these loci. Clustering of ecotypes based on Nei’s genetic distance reveal two main groups of ecotypes - north-western and south-eastern. The distribution of genetic diversity could be related with a value of allozyme polymorphism for adaptation of Siberian stone pine to different climatic conditions of the ecotypes origins or genetic processes during postglacial colonization. Average number of alleles per locus was higher in the southern limit ecotype and the parameter is decreased north-westward opposite to genetic diversity (He). Possibly selective advantage of heterozygote in newly occupied environments compensates the loss of alleles under multiple bottlenecks and founder effects.

Our data suggests that allozymes are not exceptionally neutral genetic markers but have a certain selective value in Siberian Stone pine. Allozymes are useful tools for monitoring of genetic diversity as well as for a forest tree breeding and devising of forest management techniques.

Note. Abstracts are published in author's edition