Morphometric Distances and Population Structuring in the Common Shrew Sorex araneus L. (Lipotyphla: Soricidae).

The skulls of shrews of genus Sorex from eight samplings from the European part of Russia and two from the vicinity of Novosibirsk were compared. The characteristics were identified using 22 marks on the axial skull. It was found that the centroid size differs significantly in the common and Laxmann's shrews S. caecutens and the pygmy shrew S. minutus, while for selected marks, the common and Laxmann's, as well as pygmy, shrews were significantly different in form, but the differences were very small between Laxmann's and pygmy shrews. The characteristic features of the biology of the shrews Sorex are discussed, which may contribute to understanding the general laws of the morphological evolution of the genus.

[Variability of a cytochrome b region in different chromosome races and populations of the common shrew Sorex araneus L., 1758].

The nucleotide sequence (572 bp) of the cytochrome b gene of the common shrew Sorex araneus was analyzed. In total, 92 animals of five chromosome races from 12 localities were studied. The median haplotype network has a pronounced star-like structure. The central haplotype common for all samples, except for the southern island sample of the race Sok, accounts for about 36%. The main characteristics of molecular variation in our work correspond to those obtained in other studies. We revealed the lack of a correlation between the genetic and geographic distances and also population structurization of the species. On the basis of variation of the haplotypes in the samples, a scenario of colonization of the postglacial territories by females of one or several close matrilines with subsequent rapid subdivision of the population into independent populations is discussed.

[Two types of territory used by the common shrew Sorex araneus L].

The home range of resident animals is considered as "known territory" including a "foraging region." It has been revealed that the activity of an average animal unit in the "foraging region" could be approximated by normal distribution. Estimation of activity distribution in the "known territory" (beyond the "foraging region") was impeded by means of marking since it might be difficult to detect the frequency of distant translocations, and the method does not provide an essential body of data. In the case of the common shrew Sorex araneus, the "known territory" was estimated using trap cones as animals evade them in the known areal. The "foraging region" radius of the average shrew was taken to be 30 m (95% of the animal unit activity), the radius of known territory was within the range of 180-240 m. The "foraging region" was expected to provide the animal with vital resources, and the "known territory" reflects its need for exploratory activity.

[Racial and population variability of phenotypic (cranial) characters in the common shrew Sorex araneus L., 1758].

Variability of the cranial properties of chromosomal races Serov, Manturovo and Pechora of the common shrew were studied. A consistent increase of scull size in the Serov race with moving from the plain to highlands and a skull size decrease from low to high latitudes was detected. Interpopulation variability among different races was shown to be comparable with interracial variability or to exceed it. This suggests microevolution at the level of local populations.

Natural hybridization between extremely divergent chromosomal races of the common shrew (Sorex araneus, Soricidae, Soricomorpha): hybrid zone in European Russia.

The Moscow and Seliger chromosomal races of the common shrew differ by Robertsonian fusions and possibly whole-arm reciprocal translocations (WARTs) such that their F1 hybrids produce a chain-of-eleven configuration at meiosis I and are expected to suffer substantial infertility. Of numerous hybrid zones that have been described in the common shrew, those between the Moscow and Seliger races involve the greatest chromosomal difference. We collected 211 individuals from this zone to generate a total dataset of 298 individuals from 187 unique global positioning system (GPS) locations within the vicinity of interracial contact. We used a geographic information system (GIS) to map the location of the hybrid zone, which follows a direct route between two lakes, as would be anticipated from tension zone theory. Even within the central area of the hybrid zone, there is a much higher frequency of pure race individuals than hybrid, making this a clear example of a bimodal zone in the sense of Jiggins & Mallet (2000). The zone runs through good habitat for common shrews, but nevertheless it is very narrow (standard cline widths: 3-4 km), as would be anticipated from low hybrid fitness. There is clear potential for an interruption to gene flow and build-up of reproductive isolation. As found in some other hybrid zones, there is a high frequency of novel genetic variants, in this case, new chromosomal rearrangements. Here, we report a de novo Robertsonian fission and a de novo reciprocal translocation, both for the first time in the common shrew. There is an extraordinarily high frequency of de novo mutations recorded in F1 hybrids in the zone and we discuss how chromosomal instability may be associated with such hybrids. The occurrence of a de novo Robertsonian fission is of considerable significance because it provides missing evidence that fissions are the basis of the novel acrocentric forms found and apparently selected for in certain common shrew hybrid zones.

[Evaluation of abundance of residents and immigration by irretrievable requisitioning of the bank vole (Myodes glareolus Schreber, 1780)].

The activity of average statistical species was approximated by normal distribution. This is provided by calculation of the part of resident animals without repeated hatching, i.e., the edge effect. Residence beyond the space covering 99% of species activity was considered as nonresidence. The appearance of nonresidence in general can be considered as "excursions" and "resettlement." The experiments on requisitioning of small settled animals from a preliminary marked site were carried out. It was shown that the number of settled small animals calculated using results of requisitioning corresponds to the number found during labeling with amendment to the edge effect, and immigration was constant and is not initiated by requisitioning. Only resettlements had an influence on the settlement of free space. The expected velocity of settling of the free space was calculated according to evaluation of the value of settlement and the share of "migrants" among immigrants. Second labeling of the place of hatching has shown that the expected and real paces of settlement are close.

[Distribution of two chromosome races of the common shrew (Sorex araneus L.) in the hybrid zone: may a change of the dispersal mode maintain independent gene frequencies?].

Combination of different dispersal modes may itself, without external obstacles, lead to the appearance of subdivided populations and maintain the existence of independent population systems. The common shrew, a mammal convenient for studying different levels of intraspecific differentiation, was the object of the study. Empirical data have been used for simulation taking into account the change of dispersal modes in the population area. The obtained results agree with empirical data on the distribution of races and hybrids in the hybrid zone of chromosome races Moscow and Seliger. Change of the dispersal mode may maintain independent population dynamics and, in the case of chromosome races, prevent the migration of parental individuals into the territory of the other race.

[Cytogenetic control of a hybrid zone of between two Sorex araneus chromosome races before breeding season].

Two chromosome races of common shrew, Moscow and Seliger, differ in the arm combination in 11 diagnostic chromosomes (Robertsonian metacentrics/acrocentrics). Homozygotes of both pure races, simple Robertsonian heterozygotes of Seliger race, and complex heterozygotes (FI hybrids) were detected in the found earlier between hybrid zone of these races, in the spring before the breeding seasonbreeding season. The g/oheterozygote was first discovered in race Seliger, whose chromosome formula typically contains acrocentrics g and o. The m/q heterozygote was recorded for the second time. Meiosis was studied in 16 males representing five detected karyotypic categories. No abnormal in pairing of homologs in either sex trivalent common for the species (XY1Y2) or autosome trivalents (g/o and m/q) was detected at diakinesis--metaphase I. Two hybrids displayed a theoretically expected and unimpaired meiotic configuration in a form of a very long chain comprising 11 monobrachial homologs (g/gm/mq/qp/pr/rk/ki/ih/hn/no/o). The results are discussed in terms of hypotheses on fertility of complex heterozygotes and limited gene flow in hybrid zone.

[Density-dependent behavior of the shrews (Sorex araneus, S. caecutiens, and S.minutus) in natural and experimental conditions]. / Plotnostno-zavisimoe povedenie zemleroek-burozubok (Sorex araneus, S caecutiens i S. minutus) v estestvennykh i éksperimental'nykh usloviiakh.

The behavior of three common shrew species was compared in a test of pairwise placement in a neutral territory (10 min) for various population densities in natural habitats and for animals kept isolated or in groups in open-air cage conditions. The behavior of the animals captured in nature was considered as the norm. We considered total number of social contacts (as an index of social activity), as well as the proportions of direct and ritualized aggressive interactions, contact avoidances, and friendly interactions (as a description of the interaction structure). Isolation of the shrews proved to decrease their social activity. Top frequency of interactions was observed in the animals kept in groups in open-air cages. The level of "sociality" and the changes in behavior related to different population density can be more significant in the three shrew species than the species-specific differences in their behavior.

[Comparative cytogenetics of three species of South American field hamsters of the genus Akodon (Rodentia, Cricetidae)]. / Sravnitel'naia tsitogenetika trekh vidov iuzhnoamerikanskikh polevykh khomiachkov roda Akodon (Rodentia, Cricetidae).

A karyological analysis of three species of South American field mice of the genus Akodon from four different localities of the Department of Tarija, Bolivian Republic, was performed. In Akodon simulator, 2n = 40 - 42, NFa = 42. The variation of the diploid number is caused by a polymorphism of the Robertsonian type involving six pairs of acrocentric chromosomes. Five variants of karyotypes were revealed. The chromosome set of A. sp. has 2n = 36, NFa = 40; in A. toba, 2n = 42 - 43, NFa = 44 - 46. The variation of the diploid number and the number of autosomal arms is caused by the polymorphism of the first autosomal pair. A comparative karyological analysis of A. simulator, A. sp., and A. toba revealed a high level of similarity of all karyotypic elements. Fifteen autosomal pairs of these three species have identical G-banding patterns; the others are involved in formation of larger chromosomes, representing one possible combination of the same chromosomal material. The set of rearrangements is limited only to tandem chromosome fusions.