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Karyotypes of the Petchora and Kirillov chromosomal races of the common shrew differ by six Robertsonian metacentrics with monobrachial homology, such that interracial F hybrids produce a ring-of-six configuration at meiosis I and are expected to suffer infertility. Mapping of 52 karyotyped individuals by using a unique global positioning system (GPS) revealed that the Kirillov-Petchora hybrid zone is positioned close to the river Mezen, which separated these races, and so may limit the migration of shrews across the contact zone. Although the population density of shrews was found to be markedly different with respect to habitats, the zone runs through a mosaic of habitats that are similar for both the Petchora and the Kirillov sides. This is one of the narrowest chromosomal hybrid zones among those studied in Sorex araneus with a standard cline width of about 1 km. The center of the cline is located on a bank occupied by the Petchora race at a distance of 0.4 km away from a riverine barrier. Interestingly, both the Kirillov race and hybrid individuals were found on a small island in the middle of a river fully flooded each spring. The frequencies of karyotypic variants allow us to consider the zone as an example of a bimodal zone. New Robertsonian and de novo whole-arm reciprocal translocations (WART) chromosomal variants found in the zone could be regarded as evidences of current evolutionary process in chromosomal hybrid zones. [ABSTRACT FROM AUTHOR]

The common hamster ( Cricetus cricetus L.), a rodent of the Eurasian steppes and agricultural areas, is threatened by habitat loss. Remnant populations in Western and Central Europe are small, isolated and genetically impoverished. The populations of Belgium, The Netherlands and North Rhine-Westphalia, Germany (BNN), for which Nehring proposed the epiphet canescens, are most affected by this decline. They are distinguished from more eastern populations by large, white areas on throat, chest and forelegs. These traits are sometimes also found in other populations, which casts doubt on their value as diagnostic characteristics. Here, we show that the frequency of occurrence of relatively large chest spots, chin streaks and cuffs on the forelegs is highest in BNN, where a white chest spot occurs in 67-100 % of the sampled individuals, compared to 0-8 % in Central and Eastern European populations. Additionally, hamsters from the Upper Rhine area also display relatively high frequencies of these characters (7-44 %). This suggests a common origin of BNN and Upper Rhine hamsters and an ancient expansion route along the Rhine Valley. A supplementary genetic study of two mitochondrial genes revealed extremely low diversity in both BNN and Upper Rhine hamsters but also clear differentiation and isolation between the two remaining relict populations of North Rhine-Westphalia. [ABSTRACT FROM AUTHOR]

The present paper reports karyotypic data for 76 individuals of the common shrew, Sorex araneus L., collected from 10 geographic sites in Belarus. We revealed two vast areas of polymorphism for diagnostic chromosomes of karyotypic races Białowieża ( gr, hn, ik, mp) and Kiev ( gm, hi, ko) with low frequency of metacentrics. The frequencies of the Białowieża diagnostic metacentrics decreased towards the east and the frequency of the Kiev metacentrics decreased towards the north. A high level of chromosomal variability was observed in the River Ptich basin. The contact zone of races Białowieża and Kiev was observed along the Ptich and Pripyat Rivers. The polymorphism and a low metacentric frequencies in the studied populations of the Białowieża and Kiev races from the Pripyat and Ptich basin may be associated either with selection against heterozygotes in the hybrid zone of these two races ('acrocentric peak') or with the spread of the diagnostic metacentrics of the Białowieża and Kiev races in populations characterized by 10 pairs of acrocentric diagnostic chromosomes ( g, h, i, k, m, n, o, p, q, r). Individuals with single diagnostic metacentric hk (such karyotype was previously attributed to new race Turov, Mishta et al. Acta Theriol 45 (Suppl 1):47-58, ) occurred in sites where the Białowieża and Kiev races cohabited. In accordance with these data, the previous description of the Turov race (Mishta et al. Acta Theriol 45 (Suppl 1):47-58, ) needs a revision. [ABSTRACT FROM AUTHOR]

A total of 440 skulls of common shrews, Sorex araneus, from Germany and Europe (Croatia, Hungary, Austria, and Norway) were studied. The material represented six chromosomal races (Ulm, Laska, Drnholec, Mooswald, Jütland, and Abisko) assignable to the Western European and Northern European karyotypic groups. The race of a few samples was not determined. Twenty-one linear measurements were taken on skulls and mandibles and used in this study. Pearson correlations and multiple linear regressions were used to see the relationship of the cranial variables to altitude, latitude, the chromosomal race, and the geographic location. The results from the tested samples differed; the most negative correlations to latitude were found in the samples assigned to the Western European karyotypic group (WEK), the least negative ones in the samples of the Ulm race. These results indicate the converse of Bergmann's rule. But taking into consideration all the samples of the different karyotypic groups across Europe, the correlations to latitude included positive ones, which would indicate that Sorex follows Bergmann's rule in some of the variables. The studied material of different karyotypic groups could not be differentiated in discriminant analyses. The separation of the studied races within the WEK alone was slightly better, but about 30 % of ungrouped cases remained. Only the separation of the regional samples within one chromosomal race revealed better results but was still very different between the races. This indicates that within the races, regional differences might be strong enough for a separation of the samples and that within a karyotypic group, and even more so across karyotypic groups, regional differences conceal racial differences. [ABSTRACT FROM AUTHOR]

In anthropogenically disturbed habitats, natural barriers still exist and have to be recognized, as they are important for conservation measures. Areas of phylogeographic breaks within a species are often stabilized in inhospitable regions which act as natural barriers. An area of contact between phylogeographic lineages of the common hamster ( Cricetus cricetus) was found in the Małopolska Upland in Poland. A total of 142 common hamsters were captured between 2005 and 2009. All hamsters were genotyped at 17 microsatellite loci and partial sequences of the mitochondrial (mtDNA) control region were obtained. No mixed populations with mtDNA haplotypes of both lineages were found. The distance between marginal populations was about 20 km; no hamsters were found in the area between. A principal components analysis (PCA) was performed on microsatellite data and the greatest change in PC1 scores was found between marginal samples. To define the habitat components responsible for the phylogeographic break, we compared the habitat composition of sites occupied by hamsters with those from which hamsters were absent. We found that hamsters avoided forested areas and sandy soils. The area of the potential barrier was characterized by a high proportion of woodland and unfavorable soils in comparison with neighboring areas inhabited by hamsters. They cannot settle in this area due to their high winter mortality in shallow burrows and high predation in the fields adjacent to forests. [ABSTRACT FROM AUTHOR]

Using a root vole Microtus oeconomus (Pallas, 1776) population in NE Poland we applied 31 microsatellite markers previously developed for root voles and closely related species, with the aim to improve the population genetic tools in this species. Here we present 16 polymorphic microsatellite markers grouped into four sets suitable for simultaneous amplification and genetically sex identification in M. oeconomus. The number of alleles per locus in 227 individuals varied from 7 to 26 with a low frequency of null alleles, expected heterozygosity ranged from 0.758 to 0.927, and observed heterozygosity from 0.722 to 0.947. Two loci showed significant deviation from Hardy-Weinberg equilibrium (p<0.05) and all loci showed independent inheritance. We expect these markers to be useful for studies of genetic population structure and kinship of M. oeconomus populations. [ABSTRACT FROM AUTHOR]

Reduced connectivity among local populations inhabiting a spatially heterogeneous landscape may restrict gene flow and thus contribute to diminished genetic variation within a population. The aim of this study was to determine the role of geographic distance and habitat barriers in developing genetic structure of a yellow-necked mouse Apodemus flavicollis (Melchior, 1834) population, taking into consideration the spatial organization of the landscape. A field study was carried out in two plots located in NE Poland that differed considerably in terms of the scale of habitat fragmentation: (1) a continuous forest complex, and (2) a mosaic of smaller forest habitats. The plots were separated by a water barrier comprised of a chain of lakes. DNA samples from a total of 654 individuals were examined by microsatellite analysis (5 loci). The results showed that the yellow-necked mouse population was characterized by a poorly pronounced genetic structure throughout the study area, although the statistical significance of FST for most location pairs indicated that gene flow in the area was not free. The division of the mouse population into three genetically distinct groups clearly demonstrated the significant role of water bodies as a natural barrier effectively hindering free movement of animals and thus gene flow. Analysis of the genetic structure of the mouse population throughout the study area and also within the distinguished groups indicated that the entire study population may be considered as a single metapopulation. Our results suggest that geographic distance alone is not the predominant factor affecting the genetic structure of population, but in the mosaic landscape the relative isolation of individual forest fragments, and barriers hindering movements of individuals and limiting gene flow among local populations played a much more important role. [ABSTRACT FROM AUTHOR]

The population dynamics of the Tatra vole Microtus tatricus (Kratochvíl, 1952) (Arvicolinae, Rodentia) was monitored as part of a long-term study (1996–2008) of demography of small mammals conducted in Western Tatra Mountains—Roháče, Slovakia. We observed low abundance and population densities and a balanced sex ratio but slightly more frequent captures of females. Reproductively active Tatra voles were significantly larger and heavier than reproductively inactive voles. Reproduction in both sexes tended to begin in early spring, and females moved less than males. Individuals start to reproduce after overwintering. Spatial characteristics differed between sexes, with home range size, distance travelled, and observed range length being non-significantly greater in males than in females, suggesting greater male mobility. Females remained longer on the site than did males. Mature individuals of both sexes exhibited territoriality during the peak of breeding season in spring. Home range overlap occurred more often within females, and mainly in summer and autumn. [ABSTRACT FROM AUTHOR]

A laboratory experiment was carried out in order to test the hypothesis that in a free-living population of bank volesMyodes glareolus Schreber, 1740, long distance movements and mating with females representing other breeding colonies may be a male strategy to increase their reproductive success. In an experimental cage system, the behaviour of female bank voles towards males that were either familiar to them or strangers was investigated, including whether or not females will accept stranger males as breeding partners. It was found that females did not display increased aggression towards stranger males; instead they tried to contact them and the level of female interaction did not differ significantly between the two categories of males. Based on an analysis of microsatellite markers in the genomic DNA of adults and their young, the proportion of offspring fathered by the stranger and familiar males was the same. In addition, a considerable proportion (40%) of double paternity litters was found among those obtained during the course of the study. [ABSTRACT FROM AUTHOR]