GENOGEOGRAPHIC DIFFERENTIATION OF COMMON PINE POPULATIONS IN SIBERIA

Petrova I.V., Sannikov S.N., Filippova T.V., Egorov E.V., Nemchenko E.L., Abdullina D.S.

Botanical Garden, Ural Division RAS, irina.petrova@botgard.uran.ru

The solution of problems related to conservation, diverse efficient use and protection of the extremely valuable and, generally, little disturbed natural genofund of tree populations in Siberia depends to a large extent on successful research into their population-genetic structure. However, because of the sluggish introduction of the isozymic and DNA analysis methods, this research progresses slowly in this region as compared to the European part of the range of these species. In recent decades, specialists at the Botanical Garden of the Ural Division RAS conducted a systematic study of the allozymic structure and the chorological differentiation of common pine (Pinus sylvestris L.) populations in Northern Eurasia including Western, Middle and Eastern Siberia (the Trans-Baikal region and the Amur region inclusive). This study was based on methods and principles formulated at N.V. Timofeyev-Resovskii school of thought. Over 80 population samplings (35 to 48 trees each) were subject to comparative analysis by standard methods covering 16 loci. The main results are described below.

With respect to the intrapopulation polymorphism parameters, such as the number of alleles in a locus (1.8 to 2.7 or 2.34 on the average), the proportion of polymorphous loci (56 to 87%), the actual heterozygosis (0.180 to 0.337 or 0.279±0.055 on the average), the genetic subdivision (F_ST = 0.052) and inbreeding (F_IT = 0.047), populations in Siberia and Central Kazakhstan are close to average populations in the Pinus sylvestris range.

The cluster of genetic distances (Nei, 1978; DN₇₈), which was constructed by the UPMGA method, and their ordinates in two- and three-dimensional fields clearly show two large groups of samplings. 1. Settlements of pines in Western Siberia and the Kazakh hillocky area. In the majority of cases, DN₇₈ between these settlements does not exceed the class of geographically distant populations (0.016) on the scale of intraspecific population-genetic taxons of the common pine (Sannikov, Petrova, 2003). The exception is the protractedly isolated southern insular pine forests in the extraglacial (probably refuginal) zone of Central Kazakhstan (Naurzum, Amankaragai, Ust-Kamenogorsk), which stand out against the geographical groups of the populations (DN₇₈ = 0.014-0.018). 2. Pine forests in Middle and Eastern Siberia (the Amur region inclusive). They are clearly divided into two geographical subgroups (DN₇₈ between them being over 0.014 on the average) in Central Yakutia and Middle Siberia. The latter is adjacent to insular isolates in the extreme north of Western Siberia (Purpe, Tarko-Sale, Nadym).

Marginal highly distantly isolated eastern (Komsomolsk-on-Amur, Chumikan) and northern (Tura) insular samplings are sharply differentiated (at the level of geographical races or groups of populations) from the main "core" of the genofund (with a less disjunctive range).

Generally, except for protractedly isolated settlements in the extremely southern and southern-eastern parts of the range (Central Kazakhstan, mountains of Southern Siberia and the lower reaches of Amur), the system of Pinus sylvestris populations in the eastern part of the range (Western, Middle and Eastern Siberia and Central Kazakhstan) is characterized by a relatively uniform allelic fund. This fact is probably due to their common origin from the Eastern Asian floristic province (Sannikov, Petrova, 2003) and paths of migration in the Pleistocene.

This study was supported by RFBR (grant No. 05-04-48667) and the RF HSS foundation (grant No. 9692. 2006. 04).