Vol 43, No 8 (2016)

Historical analysis of studying chromosome changes in evolution allows better understanding of the current level of research in this area. Reorganizations of the genetic system due to chromosomal rearrangements have important evolutionary consequences and may lead to speciation. Despite the complexity of evaluating the primacy of chromosome changes in speciation events, such phenomena are possible and occur in nature, as recent studies have demonstrated.

The question of how migrating birds find their way to winter quarters and back has fascinated humans since the beginning of scientific research into avian biology. Migrating birds have been shown to possess compass systems that allow them to select and maintain certain compass directions. Three such systems are known, solar, stellar and magnetic. Their details are not quite clear and need further research. Hierarchy and interaction of compass systems of migrating birds are poorly studied; different species may vary in this respect. During migration, birds learn to use maps that make true navigation possible, i.e. to detect their position relatively to the goal of movement. The physical nature of navigational maps is an object of intensive research; currently the most promising concepts are the geomagnetic and possibly olfactory maps. A significant contribution to the study of formation of navigational maps was made by Soviet/Russian researchers, whose work was published in Zoologicheskii Zhurnal (Sokolov et al., 1984). Migrating birds have no innate map, and first-autumn individuals reach their species-specific wintering areas by using compass sense and counting time that should be spent moving in certain genetically fixed directions. However, in recent years more and more data surface that suggest that juveniles (maybe not of all species) do have some mechanism of controlling their position on the migratory route that allows them to compensate for errors of the spatio-temporal programme of migration.

The population of earthworms has been studied in the main types of old-growth dark coniferous forests of Pechora-Ilych Nature Reserve (Komi Republic) that have not been subject to anthropogeniс impact for a long time. Ten species of earthworms have been identified. The greatest diversity (7 species), abundance, and biomass of earthworms has been revealed in the tall-grass fir–spruce forests. P. diplotetratheca had the greatest abundance. E. nordenskioldi nordenskioldi and E. atlavinyteae had the greatest biomass. The lowest species diversity (3 species), abundance, and biomass of earthworms have been found in the largefern, blueberry–green moss, and sphagnum–horsetail fir–spruce forests. The role of deadwood in maintaining the species diversity of Lumbricidae in dark coniferous forests has been demonstrated. The complexes of Lumbricidae have been considered in anthropogenically disturbed territories, where the following species with a habitat range to the south of the northern and middle taiga have been identified: L. rubellus, A. rosea, A. caliginosa caliginosa, and E. fetida.

Long-term data reflecting the abundance and species composition of large colonies of gulls (more than five nests, distance between the nests less than 50 m) on Aiopechan Island, West Chukotka, were compared. A comparative analysis of the data published in 1970–1984 and our data for 1989, 2000–2013 revealed significant changes in the composition and abundance of colonies over the 40-year period with simultaneous shift in the spring phonological characteristics to earlier dates. Growth in the number of the Vega gull (Larus vegae) and decrease in the number of Sabine’s gull (Xema sabini) were revealed. The number of glaucous gulls (Larus hyperboreus) was stable. A change of the dominant species in the colonies and disappearance of some colonies of the Sabine’s gull under the influence of the expansion of the Vega gull were registered. It was found that the increase in the abundance of the Vega gull occurs not owing to the increase of long-term colonies but due to the appearance of new ones.

The ringing data on Common Rosefinch obtained during thirteen field seasons (2002–2014) at the National Park “Russky Sever” (Vologda region) are analyzed. Birds were trapped in two sites 59 km apart. The age of the birds (yearlings or first breeders and adults) was determined according to the plumage color in every male captured with mist nets. The apparent survival rate of adult individuals was determined using two methods: according to the ratio of males’ age and the CJS model (Lebreton et al., 1992; Bursky, 2011). A total of 713 captures of 657 individuals were analyzed. The ratios of ages in the males from the sites studied did not differ; yearlings amounted to 56% of all males. The rate of survival in the males based on the age ratios was estimated at 44 ± 2%. The apparent survival rate obtained using the CJS model was significantly higher (61 ± 6%). The survival rate of adult rosefinches in two sites did not differ and did not depend on sex. Literature materials on the age ratio and survival of rosefinches in local populations are analyzed. There is a suggestion that the mismatch of the survival rates obtained by two methods and the high proportion of yearling males in the banding captures can be explained by the fact that the majority of individuals of that age category did not participate in nesting.

This review summarizes the available data on multilevel differentiation in the araneus species group of the genus Sorex (Eulipotyphla, Mammalia). Communication 1 gives basic information about the biology and morphological and karyotypic differentiation of some species belonging to this genus, as well as about the subdivision of one of the species, the common shrew (Sorex araneus), into intraspecific chromosomal races. The list of the 75 races known so far is included (26 of them dwell in Russia).

The intraspecies variability of Spermophilus relictus sensu lato was studied based on 27 measurements of skulls from 67 specimens of relict ground squirrels (S. relictus) and 66 specimens of Tien Shan ground squirrels (S. ralli), as well as six specimens of the relict ground squirrel from the Gissar Ridge (Tien Shan). A colorimetric analysis of skins of relict ground squirrels (19 specimens, including three individuals from the Gissar Ridge) and Tien Shan ground squirrels (19 specimens) was made. Significant intraspecies variability was found in the relict and Issyk-Kul ground squirrels, whereas the interspecies differences were small, raising questions about the species independence of the Tien Shan ground squirrel (S. ralli).

The nutrition of free-ranging bison (Bison bison), domestic horses (Equus caballus), and camels (Camelus bactrianus) were investigated from their joint grazing on a forb-grass steppe pasture. The species composition of consumed plants, selectivity of food plants, and digestibility of plant forage were assessed. Species of the plants consumed and their share in the diet have been determined using microhistological analysis of feces. The plant food selectivity (FS) was estimated by the ratio of the share of plant species in the diet of animals to their portion in the plant community of the pasture. The digestibility is calculated by the ratio of inert (undigested) components (silicon, lignin) in the diet and feces. In summer (June), these characteristics were similar for horses and bison. Both species are typical animals consuming gramineous plants: the share of these plants in their diet is 81–83%, their selectivity of graminoids is equal (1.4), and the digestibility of food is similar (49–51%). Camels differed from bison and horses by all food characteristics: forbs (mainly ruderal annual Bassia sedoides (43%) and Atriplex tatarica (20%)) predominated at 86%; graminoids amounted to 14%. The food selectivity coefficient (FS) for forbs was 2.1, including 7.7 and 2.9 for Bassia and Atriplex, respectively. The digestibility coefficient (60%) was much higher for camels in comparison with bison and horses. Under joint grazing, species with different forage selectivity (horse–camel or bison–camel) affect the plant community of a pasture evenly and preserve its species diversity.