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Chromosome sets of eight Apodemus peninsulae individuals captured in Gansu Province (Lianhuashan Natural Reserve) were studied for the first time in 2012. Chromosome sets of mice contained from 55 to 62 chromosomes and included 48 A chromosomes and 7–14 additional B chromosomes of different morphologies.

The first genetic study of the holotype of the Gansu short-tailed shrew, Blarinella griselda Thomas, 1912, is presented. The mitochondrial analysis demonstrated that the type specimen of B. griselda is close to several recently collected specimens from southern Gansu, northern Sichuan and Shaanxi, which are highly distinct from the two species of Asiatic short-tailed shrews of southern Sichuan, Yunnan, and Vietnam, B. quadraticauda and B. wardi. Our analysis of four nuclear genes supported the placement of B. griselda as sister to B. quadraticauda / B. wardi, with the level of divergence between these two clades corresponding to that among genera of Soricinae. A new generic name, Parablarinella, is proposed for the Gansu short-tailed shrew. Karyotypes of Parablarinella griselda (2n = 49, NFa = 50) and B. quadraticauda (2n = 49, NFa = 62) from southern Gansu are described. The tribal affinities of Blarinellini and Blarinini are discussed.

Fauna of small mammals of southern Gansu have been studied in three key areas: Lianhuashan Nature Reserve, Taizishan Nature Reserve, and the vicinity of Goin Ba and Lang Mu Monastery. All the key areas are associated with different altitudinal belts and, therefore, with different vegetation types. Altogether, 22 species of small mammals have been found. Among them were ten species of the order Eulipotyphla, two species of the order Lagomorpha, and ten species of Rodenta. The habitat distribution and morphometric characteristics of all species found have been analyzed. Molecular diagnostics as based on mitochondrial gene cytochrome b (cytb) and a karyological analysis were also performed. Using these methods, we revealed several new forms of small mammals. The most interesting was the finding of the Chinese dormouse Chaetocauda sichuanensis Wang, 1985. This was only the sixth report of this species, which had not been recorded earlier in Gansu Province. The small mammals were divided into three faunistic groups according to the species distribution patterns. The first group includes species the distributions of which are mainly confined to the south of Gansu and to Sichuan. The species that live in woodlands on both the eastern and southern slopes of the Qinghai-Xizang (Tibet) Plateau were assigned to the second group. The third group includes species with wider ranges, which are not limited to the slopes of the Qinghai-Xizang (Tibet) Plateau.

Karyotype studies of common shrews in the vicinity of Lake Baikal (Irkutsk Region, Eastern Siberia) resulted in the description of two new chromosomal races of Sorex araneus Linnaeus, 1758 (Lypotyphla, Mammalia), additional to 5 races formerly found in Siberia. In the karyotypes of 12 specimens from 3 locations, the polymorphism of metacentric and acrocentric chromosomes of the Robertsonian type was recorded and two distinct groups of karyotypes interpreted as the chromosomal races were revealed. They are geographically distant and described under the racial names Irkutsk (Ir) and Zima (Zi). Karyotypes of both races were characterized by species-specific (the same for all 74 races known so far) metacentric autosomes af, bc, tu and jl, and the typical sex chromosome system – XX/XY1Y2. The race-specific arm chromosome combinations include three metacentrics and four acrocentrics in the Irkutsk race (gk, hi, nq, m, o, p, r) and four metacentrics and two acrocentrics in the Zima race (gm, hi, ko, nq, p, r). Within the races, individuals with polymorphic chromosomes were detected (g/m, k/o, n/q, p/r). The presence of the specific metacentric gk allowed us to include the Irkutsk race into the Siberian Karyotypic Group (SKG), distributed in surrounding regions. The Zima race karyotype contained two metacentrics, gm and ko, which have been never found in the Siberian part of the species range, but appear as the common feature of chromosomal races belonging to the West European Karyotypic Group (WEKG). Moreover, the metacentrics of that karyotype are almost identical to the Åkarp race (except the heterozygous pair p/r) locally found in the southern Sweden. One of two Siberian races described here for the first time, the Zima race, occurs in an area considerably distant from Europe and shares the common metacentrics (gm, hi, ko) with races included in WEKG. This fact may support a hypothesis of independent formation of identical arm chromosome combinations due to occurrence of the same centric fusions in different parts of the species range.

Genetic diversity of the genus Blarinella was studied using one mitochondrial and four nuclear genes as examples. The first genotyping of shrews from the southeast of Gansu province (China), which is a typical habitat of B. griselda, has been performed. Molecular genetic analysis showed that Blarinella sp. from southern Gansu stand apart among the other representatives of the genus and can be assigned to neither of the known species.

In Western Siberia, most boundaries between common shrew chromosomal races have been found to pass along the banks of rivers, mainly those flowing in the meridional direction. The races Serov and Novosibirsk co-inhabited the right bank of the Irtysh. The easternmost point of the Novosibirsk race has been found on the middle Yenisei River, while the race Tomsk in this area was only on the right (eastern) bank.

Using a large body of observational data on the occurrence ofSorex shrews in boreal forests, we test two models that predict the structure of small mammal communities along a gradient of increasing habitat productivity. Tilman’s (1982) model predicts a humped curve of species richness along productivity gradients. In contrast, we found a linear increase in species richness with increasing logarithm of the pooled density of shrews, which we use as a measure of habitat productivity for shrews. The model of Hanski and Kaikusalo (1989) assumes a trade-off between exploitative and interference competitive abilities, and it predicts that the size structure of small mammal communities should shift from the dominance of small species (superior in exploitative competition) in unproductive habitats to the dominance of large species (superior in interference competition) in productive habitats. Shrew assemblages show such a shift. Though it is not possible to draw definite conclusions about the role of interspecific competition from our observational data, the changing size structure of local shrew assemblages with increasing habitat productivity is a predictable feature of their community structure.