ABSTRACT. Owing to distinct differences in size and shape in different taxa, spermatozoa can be of a high diagnostic value. The functional and evolutionary nature of such diversity is poorly understood. The purpose of the study was to summarize the data on the differences in sperm design and linear parameters between the subgenera Sumeriomys and Microtus (the genus Microtus) and to carry out the same comparison between the "socialis" and "guentheri" groups of species within the subgenus Sumeriomys. We obtained the data on shape and size of spermatozoa in seven nominal forms of the subgenus Sumeriomys. The species of the subgenus Sumeriomys are quite similar in sperm design, which distinctly differs from that in the representatives of the subgenus Microtus. The spermatozoa of the Sumeriomys species also differ from those of the Microtus representatives in some linear measurements and quantitative indices. These data confirm the taxonomic distinctness of the social voles as an independent subgenus Sumeriomys. Within the subgenus Sumeriomys some essential differences were revealed in sperm dimensions. The largest spermatozoa are observed in the species of the "guentheri" group, especially in M. guentheri (a head length 7.60 µκ). In M. hartingi they are slightly smaller in size (in two subspecies correspondingly 6.96 and 7.25 mk). In three nominal forms of the "socialis" group the spermatozoa are smaller (a head length 7.01-7.21 µκ), than in the "guentheri" group. The ratio of head length to its width in M. guentheri and M. hartingi is respectively 1.5 and 1.46, while in the "socialis" group, 1.42-1.47. In voles of the subgenus Microtus it is 1.8-2.4. The length of the medium part of spermatozoon's tail is the most variable character. The ratio of the sperm tail medium part length to head length in Microtus is higher than 2.8 (2.8-3.2), but in Sumeriomys it is lower than 2.8 (2.4-2.7). Особенности строения сперматозоидов у общественных полевок подрода Sumeriomys (Rodentia, Arvicolinae, Microtus) Т.А. Зоренко, Ф.Н. Голенищев РЕЗЮМЕ. Сперматозоиды у представителей разных таксонов отличаются по форме и размерам и, поэтому, могут иметь большую диагностическую ценность. Причины и пути возникновения этого разнообразия не ясны. Цель работы -сравнить между собой морфологию и линейные размеры сперматозоидов у видов полевок подродов Sumeriomys и Microtus (род Microtus), а также сравнить в пределах подрода Sumeriomys две группы "socialis" и "guentheri". Были получены данные по форме и размерам сперматозоидов у пяти номинальных форм подрода Sumeriomys. Форма сперма-тозоида сходна у всех изученных видов подрода Sumeriomys, но хорошо отличается от таковой полевок подрода Microtus. Между сперматозоидами представителей этих подродов также отмечены различия по линейным показателям и количественным индексам. Все это соответствует выделению общественных полевок в самостоятельный подрод Sumeriomys. Основные отличия были выявлены в размерах сперматозоидов. Наиболее крупные сперматозоиды обнаружены у видов группы "guentheri", в особеннос...

a b s t r a c tWe sequenced the entire cytochrome b gene in Microtus paradoxus from Turkmenistan and Microtus socialis from Crimea and Kalmykia. Phylogenetic relationships among social voles were reconstructed by the inclusion into analyses of a further 23 published haplotypes belonging to six species. The two probabilistic methods which were used in phylogenetic analyses, the Bayesian inference and Maximum Likelihood, yielded very similar results. Both trees showed two highly divergent lineages which were further subdivided into seven species. The socialis lineage encompassed four species (M. socialis, M. irani, M. anatolicus, and M. paradoxus), and the remaining three species clustered into the guentheri lineage (M. guentheri, M. hartingi, M. dogramacii). The ranges for nucleotide divergences between seven species of social voles (4.95-9.28% and 4.18-8.81% for mean and net divergences, respectively) mainly exceeded 4.3%, which is frequently regarded as the conservative cut-off between sibling species in the specious genus Microtus.

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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.

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