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The diversity of quality and the multilevel character of manifestation of biodiversity determine the necessity of using versatile approaches and methods to its study.  According to modern notions, the diversity of organisms is subdivided into taxonomic or phyletic (with respect to kinship) and typologic (with respect to categories of characters not associated with kinship) one.  Experimental methods can be used at those levels which deal with levels that are basic units of biodiversity, as well as with populations and individuals. The authors of publications presented in the present issue of the journal, while solving the problems of investigation and conservation of biological diversity, have used versatile approaches and methods

A comparative study of electrophoretic spectra of reserve globulins of seeds representing samples from 5 natural populations of Medicago falcata L. collected in the Novosibirsk Region and from 13 populations of Hedysarum theinum Krasnob. Growing in various ecogeographical zones has been carried out.
As a result of analysis of electrophoretric spectra of seeds in M. falcata populations, a similarity was found in the distribution of protein components, while in H. theinum populations a high degree of polymorphism with respect to reserve globulins of seedswas revealed.
The possibility of identification of species M. falcata and H. theinum characterized by prevalence of cross-pollination by polypeptide spectra of seeds was demonstrated, which is very important for specification of species belonging, especially for closely related species that are hard to identify by morphological characters.

Intraspecific variability of the perennial StH-genomic wild grass Elymus caninus (L.) L. were studied. Data on the variation of some morphological characters, endosperm protein and histon H1 have been obtained in accessions from different places of the area. The method of electrophoresis revealed a significant polymorphism on endosperm proteins and less one on histon H1. Homogeneity on endosperm proteins was found only in 1 from 7 studied Siberian populations. In most cases protein spectra were identical in sister-grains. This is an indication of the high level homozygous as resulted of a self-pollination.

Information is provided about trypsin inhibitors activity (TIA) in the leaves of five Hedysarum gmelinii Ledeb. populations growing in the Mountainous Altai. It was found that the populations were characterized by a certain value of TIA; the populations with the highest and the lowest value of this characteristic differed by ten times. Besides, these populations differed positively from each other and from other populations in the dimension of their leaves, number of leaves and potential seed productivity. Interdependence is discovered between the value of TIA and some morphological characteristics.

The status of the taxa Elymus dahuricus Turcz. ex Griseb.,E. excelsus Turcz. ex Griseb., E. woroschilowii Probat. and E. tangutorum (Nevski) Hand.-Mazz. in the StHY-genomic complex of E. dahuricus, has been investigated using morphological, biochemical (SDS-PAGE of endosperm proteins) and molecular (AFLP) variation characteristics. The materials include populations and separate accessions from Siberia, Far East (Russia), Tien-Shan (Kirghizstan), Tibetan and Sichuan Provinces (China). Variation of morphological characteristics and endosperm proteins patterns have been found in all populations of the complex. The same components of electrophoretic spectra were revealed for accessions of different taxonomic species. That is probably an evidence of the population variability with respect to species diagnostic characters. Differences in the variation obtained by means of DNA-AFLPs were revealed between studied biotypes. On the whole, genetic variability of investigated characters does not reflect the taxonomic status of studied species. The E. dahuricus complex seems to be a species having a wide geographical range with a wide morphological and biochemical variation. The different species need probably be relegated to infraspecific rank.

Ovulation rate, embryo mortality, mean number of live embryos and sexual maturation rate depended significantly on the phase of water vole population dynamics. Female's reproductive capacity was the highest at the increase phase and the lowest at the decline phase. Embryo mortality and sexual maturation rate were affected pleotropically by the coat colour genes. The lower reproductive capacity of dark-brown over wintered voles at all phases of population cycle, except for the peak, was due to a higher incidence of resorption of entire litters compared to brown over wintered females. At the peak, reproductive characteristics of brown and dark-brown over wintered females did not differ. Young-of-the-year dark-brown females matured earlier than brown females at the peak and decline phases and, therefore, were more reproductively successful. Analysis of voles growth in captivity revealed that dark-brown voles grew faster than brown ones. In natural population, coat colour differences in body weight of over wintered individuals were phase-dependent. Dark-brown voles usually weighed more than brown voles in the peak and decline years. It is suggested that differences in female fertility, growth and sexual maturation rate between coat colour genotypes contribute to transformation of genetic structure and act as mechanisms maintaining coat polymorphism in cyclic water vole population.

The number of wounds on skin, social ranks of captured adult males in experimental encounters, and spatial distribution of breeding individuals were studied in a population of Arvicola terrestris (L.) during two consecutive cycles (1980-1998). The study was performed within a period of intense breeding (May and June). The level of wounding of over wintered females low and independent of population density. In over wintered males, the wounding level was positively correlated with population density. The local density of reproductively active water voles within local populations did not change regardless of population fluctuations. The nearest neighbour analysis indicated that breeding females were territorial. In the male-biased local populations, heavier males were trapped closer to females. This might reflect their advantage in male-male competition and prior access to the relatively limited reproductive resource. Male body weight significantly differed among social ranks; it was maximal in dominant individuals. Dominance capacities of homozygous brown and black, and heterozygous dark-brown over-wintered males were also compared in experimental encounters. Differences among coat colour morphs were found to be cycle-dependent. At the peak and decline phases, the percentage of dominants was higher for heterozygous dark-brown than homozygous brown males. These differences may account partly for maintenance of coat colour polymorphism within the population.

Plasma 11-hydroxicorticosteroids, progesterone, testosterone, estradiol, circulating free fatty acids, and glucose were monitored in a water vole population during 1980

Inter-annual, seasonal and individual variations in food digestibility were studied in a cyclic population of water vole. Digestibility was calculated from the data on the indigestible component (lignin + acid-insoluble ash) in food and feces. Samples were collected in natural habitats and from captured water voles maintained on a natural diet for 3-5 days after capture. Estimates of food quality were based on the data for forage fibber.
Seasonal changes in digestibility were determined by seasonal alterations in the forage but found to differ at different phases of population dynamics. After the peak there was a relative loss of digestibility in animals with no loss of food quality. This is suggested to be caused by adoptions to eating un-preferable food against a background of food depletion in winter habitats overgrazed at high density. Digestibility values started to rise at low density and these inter-annual changes in over wintered animals were positively correlated with the cyclic-related changes in the mean body weight and negatively with the plasma level of free fatty acids. Relations between the digestibility and the individual body weight, social status and breeding conditions were found. Among animals over wintered at numbers decline, dominant males and pregnant females digested food more efficiently in contrast to subordinate and non-pregnant ones. It was concluded that adjustments of digestive system of animals, among other nutritional factors, may affect the population dynamics through changes in population and individual fitness.

In 1991-1996, the time course of numbers, and the variability of the basic demographic and some ecologic-physiological indices of Siberian lemming (L. sibiricus) population in the Kolyma lowland (lower reaches of the Bolshaya Chukochya river, 70