The genus Sorex is one of the most successful genera of Eulipotyphla. Species of this genus are characterized by a striking chromosome variability including XY1Y2 sex chromosome systems and exceptional chromosomal polymorphisms within and between populations. To study chromosomal evolution of the genus in detail, we performed cross-species chromosome painting of 7 Sorex species with S. granarius and S. araneus whole-chromosome probes and found that the tundra shrew S. tundrensis has the most rearranged karyotype among these. We reconstructed robust phylogeny of the genus Sorex based on revealed conserved chromosomal segments and syntenic associations. About 16 rearrangements led to formation of 2 major Palearctic groups after their divergence from the common ancestor: the S. araneus group (10 fusions and 1 fission) and the S. minutus group (5 fusions). Further chromosomal evolution of the 12 species inside the groups, including 5 previously investigated species, was accompanied by multiple reshuffling events: 39 fusions, 20 centromere shifts and 10 fissions. The rate of chromosomal exchanges upon formation of the genus was close to the average rate for eutherians, but increased during recent (about 6–3 million years ago) speciation within Sorex. We propose that a plausible ancestral Sorex karyotype consists of 56 elements. It underwent 20 chromosome rearrangements from the boreoeutherian ancestor, with 14 chromosomes retaining the conserved state. The set of genus-specific chromosome signatures was drawn from the human (HSA)-shrew comparative map (HSA3/12/22, 8/19/3/21, 2/13, 3/18, 11/17, 12/15 and 1/12/22). The syntenic association HSA4/20, that was previously proposed as a common trait of all Eulipotyphla species, is shown here to be an apomorphic trait of S. araneus.

Sorex araneus, the Common shrew, is a species with more than 70 karyotypic races, many of which form parapatric hybrid zones, making it a model for studying chromosomal speciation. Hybrids between races have reduced fitness, but microsatellite markers have demonstrated considerable gene flow between them, calling into question whether the chromosomal barriers actually do contribute to genetic divergence. We studied phenotypic clines across two hybrid zones with especially complex heterozygotes. Hybrids between the Novosibirsk and Tomsk races produce chains of nine and three chromosomes at meiosis, and hybrids between the Moscow and Seliger races produce chains of eleven. Our goal was to determine whether phenotypes show evidence of reduced gene flow at hybrid zones. We used maximum likelihood to fit tanh cline models to geometric shape data and found that phenotypic clines in skulls and mandibles across these zones had similar centers and widths as chromosomal clines. The amount of phenotypic differentiation across the zones is greater than expected if it were dissipating due to unrestricted gene flow given the amount of time since contact, but it is less than expected to have accumulated from drift during allopatric separation in glacial refugia. Only if heritability is very low, Ne very high, and the time spent in allopatry very short, will the differences we observe be large enough to match the expectation of drift. Our results therefore suggest that phenotypic differentiation has been lost through gene flow since post-glacial secondary contact, but not as quickly as would be expected if there was free gene flow across the hybrid zones. The chromosomal tension zones are confirmed to be partial barriers that prevent differentiated races from becoming phenotypically homogenous.

Onischenko S. S., Ilyashenko V. B., Searle J. B. and Borodin P. M. 2002. Morphometric difference between the Novosibirsk and Tomsk chromosome races of Sorex araneus in a zone of parapatry. Acta Theriologica 47: 381-387.A hybrid zone between the Novosibirsk and Tomsk chromosome races of the common shrew Sorex araneus Linnaeus, 1758 was found near Novosibirsk city (West Siberia, Russia) in an area unimpeded by geographic barriers. In this zone, the shrews of both races and their hybrids were trapped and karyotyped and 22 features of their cranial and postcranial skeleton were measured. Canonical discriminant analysis revealed 3 distinct groups of individuals, which corresponded to the 3 karyotypic categories involved in the analysis. The first discriminant function reflected the differences in the size of skeletal elements. The Novosibirsk shrews and the hybrids were significantly smaller than the Tomsk shrews. The second discriminant function was interpreted as a parameter of skeletal proportionality. The hybrids were significantly less proportional than the parental races. This study revealed one of the clearest examples of morphological differentiation between chromosome races of the common shrew.

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Genetic diversity between of the Novosibirsk and Tomsk chromosome races of the common shrew (Sorex araneus) was analyzed using 39 polymorphic AFLP (amplified fragments length polymorphism) markers. Exact and F-statistics tests for population differentiation demonstrated significant interracial difference in allele frequencies and significant subdivision between the races. The value of the genetic distance between the chromosome races observed in this study corresponds to that found between subspecies of mammals studied so far

We studied the dynamics of mouse-like rodent communities in the area of self-growing vegetation, which had undergone deforestation. The research is based on the results of continuous monitoring conducted from 1978 to 2019. Pitfall traps was the method of catching small mammals during the monitoring period. We used Simpson’s Diversity Index to quantify species diversity. The community similarity was evaluated by the percentage of species through Czekanowski-Sørensen Index. The studies were carried out near the “Azhendarovo” Biological Station (54°45ʹ N, 87°01ʹ E). The results of the studies showed that natural primeval communities of the taiga zone before deforestation were characterized by a multidominant structure. The dominant group included the Alexandromys oeconomus Pallas, 1776, and codominant species are represented by the genus Clethrionomys. A characteristic feature of the small mammals’ population of taiga forests is the preponderance of the Apodemus peninsulae (Thomas, 1907) over the Apodemus agrarius Pallas, 1771. On meadowlands, the genus Microtus voles prevailed. These were largely the Al. oeconomus, which accounted for 43% of all mouse-like rodents. After the deforestation, the structure changed. In the early stage of deforestation, the dominant species among rodents was the Al. oeconomus. The composition of dominant species in the recovering areas of cut-down taiga began to approach to the original state 40 years after the deforestation. Meadow communities followed the path of transformation, having no analogs in the initial period and were characterized by a significant amount of ruderal vegetation.

Работа выполнена при поддержке гранта РНФ 14-50-00029 «Научные основы создания национального банка-депозитария живых систем». Our research is based on the results of catchings with the subsequent girdling from 2008 to 2014 at Azhendarovo Biological Research Station of Kemerovo State University located in the valley of the middle reaches of the Tom River (54 о 45'N; 87 о 02' E). We caught 761 Motacilla individuals during this period. To evaluate the distribution of forms, we used the collection funds of the Zoological Museum of Tomsk State University, the Department of Biodiversity and Bioresources of Kemerovo State University, and the Zoological Museum of Moscow State University, in total 111 specimens. No bird was harmed during this research. All counts were conducted according to Ethical Standards. M. flava and M. tschutschensis. M. flava beema nests in the territory of the Kuznetsk-Salair mountain region and in the basin of the Tom River. Usually, the most massive movements of M. flava beema begin in the second decade of July and reflect juvenile migrations of the nesting wagtails. The peak of flight occurs in the third decade of July. The increase in migratory activity since the end of August is probably due to a small number of M. tschutschensis plexa in the flight. The spring flight of "transit" M. tschutschensis plexa happens in the second half of May. M. flava beema arrives at the end of April-May. M. citreola and M. (citreola) werae. M. werae werae nests in the Kuznetsk-Salair mountain region, nesting of M. citreola citreola requires factual confirmation. M. werae migrates to places of winterings at the end of July-the first half of August, M. citreola citreola-in August or in the beginning of September. In spring, the first M. werae are noted in the second decade of May, and passing M. citreola are recorded in the last decade of May-in the beginning of June. M. cinerea arrives in the third decade of April or in the beginning of May. The most massive flying to the places of winterings took place in the third decade of July-in the first decade of August. The most recent capture was registered on September 15, 2008. We did not reveal any significant differences in terms of departure of adult and young individuals. M. alba and M. personata. A border between the habitats of M. alba and M. personata lies in the Kuznetsk-Salair mountain region. M. alba is common in plains, whereas M. personata is widespread in mountain and foothill territories. Both species, which actively hybridize with each other, live in the valley of the Tom river. The width of the zone, where hybrid individuals are constantly encountered, makes up about 60 km; in the zone up to 150 km the presence of hybrid individuals is already a relative rarity. The article contains 3 Tables, 8 Figures, 49 References.