Роль межвидовой конкуренции в биотических сообществах мало изучена. Представленная работа посвящена трансформации таксоцена восточноазиатской и полевой мышей, включающей экспансию ареала последней на фоне глобальных средовых изменений. Главная цель - в сравнительной оценке длины отделов кишечника полевой и восточноазиатской мышей в аспекте конкурентного неравенства этих видов и в анализе роли этого неравенства в динамике их таксоцена. Показано, что эффективность ассимиляции углеводов, составляющих основу растительных тканей, в кишечнике восточноазиатской мыши существенно выше, чем у полевой, при незначительных различиях в ассимиляции белков и липидов. Мы заключаем, что восточноазиатская мышь является сильнейшим трофическим конкурентом этого таксоцена и что конкуренция играет большую роль в его трансформации. Однако экспансия ареала полевой мыши не может быть прямым следствием ни конкуренции, ни глобальных изменений, по отдельности. Обсуждается механизм взаимосвязи этих причин трансформации таксоцена полевой и восточноазиатской мышей. The role of interspecific competition in biotic communities is poorly understood. The study deals with transformation of the Korean field mouse/stripped field mouse taxocene, which includes range expansion of the second one during global environmental change. The main goal is a comparative estimation of main intestine divisions’ length in these species to define their competitive asymmetry and to understand its role in the taxocene dynamics. We show that the assimilation carbohydrates prevailing in plant tissue is significantly more effective in the Korean field mouse intestine than in the stripped field mouse intestine, while their difference in the protein and lipid assimilation was low. We conclude that the Korean field mouse is the stronger trophic competitor in the taxocene, and the competition play an important role in its transformation. However, neither competition nor global change can directly influence range expansion of the stripped field mouse separately. A interactive mechanism of their influences on the Korean field mouse/stripped field mouse taxocene transformation is discussed.

The ranges, spectra of habitat types, and food spectra of artiodactyls in the Far East have been studied. It has been supposed that the overlap of ranges and habitat-type spectra should decrease with an increase in the overlap of food spectra. However, all the three similarity indices have proved to be positively correlated with each other, suggesting that, on the regional scale, the negative role of trophic competition in artiodactyl communities is insignificant, probably because of their low abundance. Conversely, the similarity of food spectra may be regarded as a factor accounting for the overlap of ranges and habitat spectra and, on a large-region scale, for the maintenance of high species diversity.

The numeration of the chromosomes, which can be used to describe the karyotypes of various chromosomal forms from different geographical regions, has been proposed for the Maximowicz's vole Microtus maximowiczii. Application of FISH analysis has allowed us to show homology of Robertsonian rearregement (11/20) inkaryotypes of voles from Transbaikalia (2n = 41 and voles from Norsky reservation in Amur Region (2n = 40).

The genetic variability of brown bear Ursus arctos from the southern part of the Russian Far East was first ex- amined based on the variations in the mitochondrial DNA cytochrome b sequence. The presence of two phylogenetic groups of haplotypes described previously for other parts of the species range was demonstrated. Part of the samples belonged to the haplotype group distributed across the whole range, while another part belonged to the rare group previously only reported for Japan and Alaska. These findings partially clarify the pattern of brown-bear colonization on the territory of the Russian Far East and Japan.

The data on the first finding of the Mongolian toad, Bufo raddei, on Sakhalin Island are given. Habitation of Microtus fortis in northwestern Sakhalin proved to be true. The assumption on the appearance of these animals on the island during the latest period of the existence of a land bridge during the warming begun about 7 thousand years ago is stated.