Data on variability of nuclear ribosomal DNA ITS 1-2 markers of Betula turkestanica, B. tianschanica, B. procurva

The article includes preliminary results of nuclear ribosomal DNA ITS 1-2 region analysis of Betula turkestanica Litv., Betula tianschanica Rupr., Betula procurva Litv. implemented for clarification of taxonomic status, phylogenetic relationship and origin of these birch species. The range of B. procurva, B. turkestanica, B. tianschanica, is confined to the mountain system in southeast Central Asia (Pamir-Altai). B. procurva has a disjunctive range and is also found isolated from the main range in the mountainous part of the Urals (boreal forests zone and the Trans-Ural forest-steppe). These birch species have morphological features of B. microphylla Bunge and B. pendula Roth, however they also possess distinctive morphological traits. The paper shows the level of differentiation and the distribution of genetic variability between groups of haplotypes, and also provides a genetic network which demonstrates the relationships between the studied samples. Based on the results of genetic analysis, the origin and phylogenetic relationships of B. procurva, B. turkestanica, B. tianshanica are suggested. The resulting haplotype network confirms the hypothesis of a possible common ancestor of B. procurva, B. pendula from the section Betula (white birches) and B. nana from the section Apterocaryon (dwarf birches). A conclusion is made about the informativity of the ITS 1-2 region of nuclear ribosomal DNA for the differentiation of the studied birch species on the territory of Kyrgyzstan. At the same time, it is emphasized that the highest haplotype diversity is typical for B. procurva specimens with divergent position of the sample from the Kurgan region, which indicates the long-term existence of this disjunction.