Secondary types of food in the diet of a small-sized mammalian herbivore: from species ecology to habitat inferences

A macroscopic analysis of stomach contents is undertaken in the common vole, Microtus arvalis, obscurus chromosomal form in order to assess the patterns of non-herbivorous foraging activity of a herbivore distributed in different Eurasian biomes. The samples are collected in the Ural Mountains at midsummer (8 localities, 60° 38′ N to 51° 07′ N), and in winter (one locality, 56° 37′ N). Based on the frequency of occurrence and quantitative abundance in stomachs, photoassimilating parts of vascular plants are considered as the primary food category and inflorescences, roots, seeds, mycorrhizal fungi, arthropods, chitin fragments, colorless amorphous matter, and mosses are recognized as the secondary food categories. Although no alternatives to the primary food are found, some of the supplements substitute one another either geographically (fungi in the north versus mature seeds in the south) or by the vertical layers of habitats (seeds and arthropods in the herbaceous layer versus roots and fungi in the shallow layers of soil). Non-staple food consumption in different latitudinal zones at midsummer reflects spatiotemporal dynamics of food availability. From taiga to steppes of the Urals, the common vole is sporadically included in soil foraging but the consumption of mycorrhizal fungi (Glomerales) is only revealed within the zones of dark coniferous forests. The results suggest that the extents of inclusion of a herbivore in soil food webs might vary among ecosystems. In a paleoecological perspective, the analysis of stomach contents in a herbivorous micromammal might reveal fine-scale details of the habitats and provides insights into the stages of the growing season.     

The genetic diversity of burbot (<Emphasis Type="Italic">Lota lota</Emphasis> L., 1758) of Western Siberia (the analysis of the mtDNA control region polymorphism)

The genetic variability of burbot (Lota lota L., 1758) inhabiting the Ob-Irtysh and Taz river basins in Western Siberia has been studied based on the polymorphism of the hypervariable fragment of mtDNA control region (407 bp). The analysis of 134 fish samples revealed 30 haplotypes, 23 of which were new. Among haplotypes, previously detected in Eurasia and North America, EB30 was the most frequently found in Western Siberia (45.5% frequency). The results of our study are in agreement with previous research pointing to the genetic differentiation of two burbot subspecies, L. l. lota and L. l. maculosa, and indicate that burbot inhabiting the Ob-Irtysh and Taz river basins belong to the Eurasian-Beringian clade (nominative subspecies L. l. lota). However, a high genetic diversity of burbot in Western Siberia, along with a relatively high differentiation of burbot groups within studied territory, points to a regional specificity of burbot population.     

Genetic Variability in the Yellow-Necked Field Mouse (<Emphasis Type="Italic">Sylvaemus flavicollis</Emphasis> Melch., 1834, Muridae,Rodentia) at the Eastern Border of the Range

The first characterization of the genetic variability in populations of S. flavicollis on the eastern border of the range is presented. Seven individuals from the most northeastern habitat of the species (Middle Urals) were karotyped. No deviations from the standard chromosome set, either by the chromosome number or morphology, were revealed. Analysis of the mtDNA cytochrome b gene sequences (1133 bp) in 44 individuals from five populations on the eastern border of the species range (Middle and Southern Urals) resulted in identification of 17 haplotypes. All haplotypes were new and not found earlier in other parts of the species range. The genetic diversity indices and analysis of the demographic and genetic structure indicate a relatively recent origin of the populations under study as a result of rapid expansion. Phylogenetic analysis (97 haplotypes, including the GenBank data) showed that all haplotypes described at the eastern border of the range belonged to the same phylogroup distributed in the Balkan region, Northern and Eastern Europe, and Russia (Samara oblast). Close relationships between the examined populations and the populations from the northern part of the species range in Eastern Europe was demonstrated.