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The final isolation of Europe from Asia took place comparatively not long ago-in the early Holocene-late Pleistocene which led to the division of Microtus hartingi area into two isolated parts (Asian-Central and West Anatolia and European-southern Balkans). The Northern Mediterranean was influenced by considerable climatic and habitat fluctuations that caused fragmentation of a potential area of Microtus hartingi and promoted microevolutionary processes. The purpose of the work was evaluation of the range disjunction influence on diversification of the species. We analyzed (1) copulatory behavior, (2) exploratory activity and ability to overcome the stress, (3) growth and development of pups, and also (4) hybridization success in the two nominal forms of M. hartingi-M. h. lydius and M. h. strandzensis. Considerable changes in behavior of individuals of two subspecies were obtained. As a result of the hybridization of the two forms, viable and prolific posterity of F1 was received, but the subsequent cross breeding including backcrossing sterility of males and high mortality of posterity began to be established. The testes and the epididymis of the hybrids were with smaller weight in comparison with parents' subspecies, especially M. h. lydius, reduced quantity of spermatozoa and small percent mobile of them which confirmed the lower level of spermatogenesis. We assume that evolution of the phenotypic characteristics of the voles was supported by gene drift and probably by the selection, induced by the stress more strongly, than changes in the genotypic characteristics, e.g. distinctions on cytochrome b and the karyotype are not significant. This can be explained as an influence of specific ecological conditions and fragmentation of the habitats in the Northern Mediterranean Region. Until recently M. h. lydius and M. h. strandzensis were considered as subspecies. However, they reached considerable degree of a divergence and the question of their specific status has to be considered additionally.

The aim of the study was to evaluate the phylogeny and relationships of the root vole Alexandromys oeconomus with the other species of the tribe Microtini, using the comparison of the characteristics of sexual behavior. Thirteen copulatory behavior patterns that form a specific stereotype of the species' mating behavior are used. The results showed the multiple thrusting stereotype of copulation, which includes separate intromissions and a very first mount with intromission, is ending with ejaculation (from 10% to 48%, depending by the investigated population). The number of ejaculations is comparatively big, varying from 4 to 7 (an average of 4.6) and the genital stimulation rate is from 68 to 260 thrusts. The males of the root vole noted active courtship for the female, which is accompanied by singing, waltzing and marking of the substrate. Marking the territory is manifested by rubbing the femoral region on the substrate, in which the secretion of the hip glands is applied to it. Analysis of the distances (or similarities) between species according to patterns of sexual behavior using the method of cluster analysis indicates the proximity of A. oeconomus to species of the genus Alexandromys and a considerable distance from representatives of the genus Microtus (Microtus s.str. and Sumeriomys). Significant interpopulation differences in copulatory behavior of the Central Asian phylogroup are established (54% of all the behavioral traits studied). The transformation of the stereotype of mating in individuals from Beringia phylogroup in comparison with the Central Asian one is particularly significant and reaches 77% of all the behavioral traits. The data obtained by the analysis of the copulatory behavior of the Alexandromys oeconomus support the separation of the species from genus Microtus. How to cite this article: Zorenko T.A., Atanasov N.A. 2018. Copulatory behavior supports a new insight into taxonomic status of root vole Alexandromys oeconomus (Rodentia, Arvicolinae) // Russian J. Theriol.

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