Nikolaeva O. Variation and viability of Juniperus excelsa Bieb. in Crimea.

The thesis is devoted to the studies of population and biological characteristics, morphometric variation and genetic polymorphism of Juniperus excelsa Bieb. in Crimea to assess the viability of populations and forecast maintenance of their genetic diversity. The studies have shown that on the whole there are no significant loss of diversity by both morphometric and genetic parameters in J. excelsa in Crimea compared to populations from other parts of its range, that is important for the species viability. However, most populations are characterized as degraded and seriously damaged by an increased human impact on them, while a decrease in this pressing improves their rectoration and vitality state. Most of reproductive trees in all populations are characterized by low galberry yields. Moreover, despite a relatively large total number of seeds in galberries (5,6 pcs.) in J. excelsa populations in the Crimea, there were very few (3.5%) full seeds, compared with populations in other habitats. A high level of genetic polymorphism and an excess of heterozygotes, which is probably related to the long duration of this species life cycle, is characteristic of J. excelsa populations in Crimea. Level of the observed heterozygosity in J. excelsa population from Lebanon is on average more than 1.4 times higher than those levels in Crimean populations. In the course of our studies, we have selected J. excelsa populations in Crimea, perspective to become genetic reservations of this species. According to the forecast, at present J. excelsa in Crimea has the genetic potential to restore its degraded populations provided there is a cessation of the significant anthropogenic disturbance.