Genetic Differentiation of Dwarf Siberian Pine, Pinus pumila (Pall.) Regel, Populations from the Pacific Region

The genetic structure and differentiation of 12 Siberian dwarf pine populations from Chukotka, the Kamchatka Peninsula, Sakhalin Island and Kunashir Island were studied using 28 allozyme loci ( Adh-1 , Adh-2 , Fdh , Fest-2 , Gdh , Got-1 , Got-2 , Got-3 , Idh-1 , Lap-2, Lap-3 , Mdh-1 , Mdh-2 , Mdh-3 , Mdh-4 , Mnr-1 , Pepca , 6Pgd-2 , 6Pgd-3 , Pgi-1 , Pgi-2 , Pgm-1 , Pgm-2 , Skdh-1 , Skdh-2 , Sod-2 , Sod-3 , Sod-4 ). In total, 26 of the studied loci (92.9%) turned out to be variable, the mean number of alleles per locus was 2.3, and the mean heterozygosity ( H E ) was 0.248. The levels of intrapopulation variability were close to the mean values in the majority of populations. Interpopulation differentiation within the population group of Kamchatka turned out to be quite high ( F ST = 0.028). Weak differentiation was observed between two northern Chukotka populations ( F ST = 0.013), as well as two Sakhalin Island populations ( F ST = 0.013). The maximum level of genetic differentiation was found between the populations of Kunashir Island, growing in contrasting environmental conditions in a geographically small area ( F ST = 0.041). The genetic differences between the Kunashir populations of Siberian dwarf pine are comparable to the differences between the populations of the Baikal zone, where this species grows in contrasting ecological conditions. On the whole, the differentiation of populations in the Pacific region was 0.07. Nei’s genetic distances (D N ) range from 0.005 between two populations of Kunashir Island to 0.043 between the populations of Kamchatka and Kunashir. Factor analysis revealed clusters of populations by geographical origin, and also showed a high degree of differentiation between localities within Kunashir Island and the Kamchatka Peninsula, which may indicate a high degree of adaptation of individual populations to their habitat. Thus, we can conclude that the high rates of interpopulation differentiation of Siberian dwarf pine depend not only on geographical origin, but also on growing conditions.