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Chromosome approaches in studies of the taxonomic and genetic diversity of rodents in the Lower Volga region. Conclusions and outlook of their application. - Baskevich M.I. and Oparin M.L. - Chromosome data for the common voles (Microtus arvalis sl l.) and birch mice (Sicista) from the betulina and subtilis groups, representatives of the Sylvaemus genus from the left and right banks of the Volga river in the Saratov region are presented. The data obtained are used for specification of the taxonomic and genetic diversity of rodents in the Lower Volga region. The geographic and spatial distributions of some of them in the region have been determined more precisely by using chromosome markers as well. Evolutionary and ecological aspects of the chromosome variability in rodents and prospects of the chromosome approach application to Rodentia in the Lower Volga region are discussed.
Key words: chromosomes, rodents, taxonomic status, genetic diversity, geographic and spatial distribution, Lower Volga region.
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Ecology, morphological variability and distribution of Stephanodiscus niagarae (Bacillariophyta) in Russia. - Genkal S.I. and Lepskaya E.V. - The morphology of the centric diatom algae Stephanodiscus niagarae from Lake Sarannoe (Bering island) was studied by using scanning electron microscopy. Morphological variability of the main structural valve elements and its regularities were revealed, an assessment was made of the concernment of the quantitative features under study. Data on the distribution and ecology of the species were specified.
Key words: Bacillariophyta, Stephanodiscus niagarae, morphology, ecology, distribution, Lake Sarannoe, Bering island.
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On population analysis of the abundance dynamics mechanisms in Apodemus agrarius in the Lipetsk region. - Duvanova I.A., Khitsova L.N., Nedosekin V.Yu., and Drozdova V.F. - Studies were made in the Lipetsk region in 1987 - 1997 and 2001 - 2007. The patterns of the seasonal and long-term abundance dynamics and population structures in Apodemus agrarius were determined by using univariate and multivariate statistics. The observable changes of the numbers of mice were found to be a complex process with cyclic periods of nearly two years and one year. The quantity of precipitations strongly influences the studied species. The period of this factor was found to be equal to the two-year periods of the field mouse cycles.
Key words: Apodemus agrarius, population cycles, regulation mechanisms, exogenic factors.
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A correlation between Quickbird imagery characteristics and vegetation, soils and their salinity in the North Caspian region (Dzhanybek research station, RAS). - Konyushkova M.V. and Vyshivkin A.A. - Quickbird imagery has been analyzed at the Dzhanybek research station (RAS) in terms of its utility for assessment of vegetation, soils and their salinity in virgin areas. On the basis of 78 sampling sites, near-IR reflectance and calculated NDVI and NDCI indices (the latter proposed by us) are shown to be the most informative parameters to discern between different types of soils and plant communities. Discriminant analysis has shown that nonsaline dark-colored soils can be automatically discriminated with a very high accuracy (~80%); other categories of soils and salinity can be distinguished with an insufficient accuracy. With an accuracy of ~70%, the group of Artemisietum pauciflora, Kochietum prostratam, and Salsoletum laricina communities can be separated from other vegetation groups.
Key words: digital soil mapping, image analysis, discriminant analysis.
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Vertical distribution of the zooplankton of a small river. - Krylov A.V., Tsvetkov A.I., and Malin M.I. - A vertical stratification of water mass and a non-uniform distribution of zooplankton communities were observed at a deep-water site of the free watercourse zone and in the frontal area of the backup water pinch zone. The most density of zooplankton accumulation has been fixed in the near-bottom layer, where decreases of the water temperature and the content of dissolved oxygen, and an increase of the electroconductivity of water are noted. Among probable causes of such a distribution the 'second-bottom effect' created by higher-density water is proposed.
Key words: zooplankton, small river, number, biomass, vertical distribution.
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Dependence of the composition of the flavonoid complex Helichrysum arenarium (L). Moench on the vegetation conditions in the Saratov region. - Mashurchak N.V., Kashin A.S., and Ignatov V.V. - The qualitative and quantitative composition of the flavonoid complex in plants of 28 natural populations of Helichrysum arenarium (L.) Moench from 17 districts of the Saratov region was studied. Distinctions in the number of flavonoids presented in trace quantities are observed in plants from various districts of the region in the absence of distinctions in the qualitative composition of the basic components of the flavonoid complex. However, no strict zonal distribution of this variability has been revealed. The maximum concentration of naringenin was observed in the populations from the central and western districts of the right-Volga-bank region. In the northern and southern directions in the right-Volga-bank region the concentration of naringenin was reduced. But an especially low concentration of naringenin was detected in plants from the Trans-Volga region, reaching a minimum in the extreme east. Within the region in the direction from north to south the content of naringenin in plants from the steppe biotop increased with a higher intensity than in plants from the biotop of a steppefied pine forest.
Key words: Helichrysum arenarium, flavonoids, population, variability, Saratov region.
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Distribution pattern and some aspects of fern ecology at anthropogenous habitats in the northern Lower-Volga region. - Berezutsky M.A. and Pavlovsky A.M. - Findings of six fern species (Polypodiophyta) in different types of anthropogenous habitats in the northern Lower-Volga region within the Saratov region (forest plantations, railway embankments, and ponds) are reported. Sites of three fern species included in the Red Book of the Saratov region were revealed in forest plantations. Of special interest is the finding of Gymnocarpium dryopteris (L.) Newm in forest plantations, because it is an exclusively rare species even in natural habitats.
Key words: ferns, anthropogenous habitats, protected species, Saratov region.
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A submerged trap for quantitative measuring of heterotopic insect imago emergence on the water-air boundary in lentic waterbodies. - Dyomina I.V., Yermokhin M.V., and Dyomin A.G. - A new design of the submerged funnel trap is described. This trap is applicable for quantitative measuring of heterotopic insect emergence through the water surface.
Key words: submerged funnel trap, Chironomidae, heterotopic insects, emergence.
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Dynamics and possible causes of Pygmy Cormorant (Phalacrocorax pygmaeus, Pelecaniformes) expansion in the northern Lower-Volga region and adjacent territories. - Zavialov E.V., Tabachishin V.G., Yakushev N.N., Kharitonov S.P., and Mosolova E.Yu. - Data of registration of Phalacrocorax pygmaeus in the Saratov region are reported. The growing number of observations of these birds outside their nesting habitat in the migration period is obviously caused by the abundance increase of the species on its nesting places. Further dynamics of Ph. pygmaeus distribution in the Lower-Volga region and adjacent regions requires a careful study.
Key words: Phalacrocorax pygmaeus, distribution dynamics, Saratov region.
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