Ecological preferences of forest voles

Basic climatic parameters (annual average air temperature and annual amount of precipitation) over 12–25 years have been analyzed with regard to their values corresponding to different levels of abundance in three species of forest voles: Clethrionomys glareolus (in 11 areas of the species range), Cl. rutilus, and Cl. rufocanus (in three areas each). The results show that the abundance of all these species correlates significantly with fluctuations of annual average temperature, with the correlation being negative in Cl. glareolus and Cl. rufocanus but positive in Cl. rutilus. In addition, the abundance of Cl. rufocanus shows a significant correlation with annual precipitation. Voles inhabiting different geographic regions may reach high abundance under different conditions. As for the species range as a whole, however, Cl. glareolus is more ecologically flexible than the other two voles. This species is also more warmth- and moisture-loving, while Cl. rufocanus is more cold-loving and xerophilous, with Cl. rutilus occupying an intermediate position between them. Clethrionomys rutilus is most temperature-dependent and stenothermic among them, whereas Cl. glareolus is indifferent to the factors studied.     

Endogenous ethanol and acetaldehyde in the mechanisms of adaptation of small mammals to northern conditions

Study results on the condition of endogenous ethanol—acetaldehyde system in northern red-backed vole (Myodes (=Clethrionomys) rutilus Pallas, 1779), common species of northern latitudes, are presented. Concentrations of endogenous ethanol (EE) and acetaldehyde (EA) in blood, activities of alcohol dehydrogenase in ethanol oxidation reactions (ADH_I) and liver acetaldehyde (ADH_II) and aldehyde dehydrogenase (ALDH) reduction, and catalytic parameters of these enzymes are determined for winter and summer periods. Changes in ethanol—metabolizing dehydrogenase enzyme system in northern red-backed vole leading to statistically significant (p < 0.01) increase in blood EE and EA concentrations compared to white nonpedigreed laboratory rats without adaptations to cold (especially in winter period) are determined to serve ecoadaptive, antistress functions, comprising one of the systems for regulation of metabolism intensity in small mammals inhabiting extreme northern conditions. Ecological—physiological functions of EE and EA system are increasing the organism’s resistance to the influence of cold temperatures and maintaining thermoregulation even under rapid, considerable environmental temperature drops.     

On adaptations of trees and shrubs in the north of the Russian Far East

Specific ecological features of trees (Chosenia arbutifolia and Betula lanata) and shrubs (Pinus pumila and Duschekia fruticosa) at the northern limit of their distribution are compared. New biomorphological adaptations of these species under extreme conditions are described.     

Current state and long-term changes of the <Emphasis Type="Italic">Crenomytilus grayanus</Emphasis> community in Vostok Bay,Sea of Japan

The composition and structure of the Gray mussel (Crenomytilus grayanus) community in Vostok Bay of the Sea of Japan have been studied. A total of 165 species have been identified in the macrobenthos. Its species composition has changed insignificantly since the 1970s. The total biomass of the biocenosis has decreased, and the size-age composition of the C. grayanus population has changed due to poaching. The trophic structure of the community has also changed, with the Shannon indices of species diversity and equitability (E) becoming lower, due to intensive organic pollution of Vostok Bay resulting from increasing recreational activities and sewage discharge.     

Comparative Analysis of Coat Color Morphs in a Polymorphic Population of the Northern Mole Vole

Long-term stationary observations (1985–2000) on a polymorphic population of the northern mole vole (Ellobius talpinus Pall.) in Kurgan oblast were performed using the mark-recapture method. Original data were obtained on the abundance and structure of this population, which comprised individuals of three color morphs: black, brown, and intermediate (bicolor). Each morph proved to have its specific features with respect to abundance, age and sex composition, migration, birthrate, mortality, and life span. In general, this polymorphism contributes to population heterogeneity and the maintenance of population homeostasis.     

Long-term population dynamics of ixodid ticks and development of tick-borne encephalitis foci under conditions of the middle taiga subzone

Long-term (1995–2003) population dynamics of ixodid ticks and their main hosts (small mammals) and conditions providing for the formation of tick-borne encephalitis (TBE) foci were studies in the middle taiga subzone (Karelia). The results show that the bank vole (Clethrionomys glareolus Schr.) is the main host for the larvae and nymphs of Ixodes persulcatus Schulze, 1930 and for the larvae, nymphs, and adult individuals of I. trianguliceps Birula, 1895. The proportion of ticks feeding on this species (relative to their total number) reaches 63.3% (64.0% of I. persulcatus and 61.1% of I. trianguliceps). Activity of a TBE focus is determined primarily by the abundance of bank voles of older age groups.     

Assessment of nonselective elimination effects in rodent communities by methods of geometric morphometrics

Methods of geometric morphometrics and population phenogenetics have been used to evaluate morphogenetic rearrangements in two sympatric species of Myodes voles (M. glareolus Schreb. 1780 and M. rutilus Pall. 1779) from syntopic populations recovering after exposure to local “ecological vacuum” created as a result of rodent extermination in a natural focus of hemorrhagic fever in the southern taiga subzone of the Udmurt Republic. The model used in the study simulates the situation that arises upon nonselective elimination of rodent populations and communities in spring and their subsequent recovery. Analysis of variation in the size and shape of the mandible and in a complex of 30 nonmetric cranial characters has revealed similar (parallel) and species-specific morphogenetic and epigenetic changes occurring during the recovery of local rodent community. Species-specific differences in the pattern of change in the parameter characterizing within-group morphological disparity in the mandible shape (MNND) have been revealed between the dominant species (M. glareolus) and the subdominant species competing with it for territory (M. rutilus). Different reactions of close Myodes species in the course of filling the ecological vacuum are considered as a result of reduction in the level of competition for the subdominant species and a compensatory increase of morphological disparity in the dominant species under conditions of low density and incomplete composition of the community, in accordance with Chernov’s (2005) ecological compensation principle.     

Role of small mammals in natural and anthropogenic landscapes of the right-bank region of Saratov oblast

Small mammal communities inhabiting natural and anthropogenically transformed areas of the right-bank region of Saratov oblast are fairly similar in species composition. They are represented by wide-spread, common species that, against the background of a low population density of typical steppe species, make a major contribution to the community. The highest ecological tolerance is characteristic of the striped field mouse Apodemus agrarius, which is widespread in the study region and dominates in the majority of natural biotopes and in agrocenoses; the common vole Microtus arvalis is scarce in agrocenoses.     

Gradient Genogeographic Analysis of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. Populations in Europe

Gradients of Nei's genetic distances between 15 samples of Pinus sylvestris L. trees were analyzed along three submeridional transects, from Scandinavia to the Mediterranean and Transcaucasia. As a result, distinct chorogenetic differentiation was revealed between the populations of this species growing in climatically specific regions of northern and southern Europe. Considerable Nei's distances (DN = 0.045–0.056) and their gradients, combined with differences in stable phenotypic characters (the composition of monoterpenes and morphological parameters of cones) determined at the Pyrenean and Caucasian mountain borders, suggest that the P. sylvestris species structure includes two South Eurasian subspecies, the Pyrenean P. sylvestris L., ssp. iberica Svoboda and the Transcaucasian P. sylvestris L., ssp. hamata (Stev.) Fomin.     

Lipid peroxidation rates in <Emphasis Type="Italic">Taraxacum officinale</Emphasis> Wigg. and <Emphasis Type="Italic">Vicia cracca</Emphasis> L. from biotopes with different levels of soil pollution with heavy metals

The rates of lipid peroxidation (LPO) have been studied in Taraxacum officinale Wigg. (Asteraceae) and Vicia cracca L. (Fabaceae) from urban ecosystems with different levels of soil pollution with heavy metals (HMs), including Pb, Zn, Cu, and Cr. The former species responds to the increased HM contents by intensification of LPO processes, with their parameters correlating with the concentrations of Pb, Zn, and Cu in the soil. In the latter species from the same biotopes, conversely, LPO homeostasis remains actually undisturbed.     

Effect of interspecific competition on functional properties of plants in mountain-steppe communities of the Gobi

The isotope ratios δ¹³C and δ¹⁵N and the contents of nitrogen, carbon, and mineral substances have been studied in the leaves of Ephedra sinica, Allium polyrhizum, and Stipa glareosa plants growing separately or together under arid conditions of the Gobi (Mongolia). The contents of nitrogen, mineral substances, and δ¹⁵N have proved to decrease when these species grow together, providing evidence that they compete for environmental resources. The nitrogen content decreases to the greatest extent in E. sinica due to the low competitiveness of this species. The direction of change in δ¹³C in E. sinica is opposite to that in A. polyrhizum and S. glareosa. Differences in physiological mechanisms of adaptation to stress between these species provides a basis for attributing them to different functional groups and for predicting the result of their competition upon changes in climatic conditions.     

Effect of Ecological Factors on the Accumulation of Fluorine by Larches, <Emphasis Type="Italic">Larix gmelinii</Emphasis> (Rupr.) Rupr. and <Emphasis Type="Italic">L. sibirica</Emphasis> Ledeb., in Eastern Siberia

The accumulation of fluorine in the trunk wood and branches of Larix gmelinii growing on soils with a naturally increased fluoride content and of L. sibirica growing in a zone affected by atmospheric emissions from an aluminum plant has been studied. Based on results of in vivo and in vitro experiments, it is concluded that larch trees manifest individual differences in their response to fluorine.     

Comparative analysis of the effect of predator odor on morphological and physiological parameters of adult male Campbell hamsters (<Emphasis Type="Italic">Phodopus campbelli</Emphasis>) and dwarf hamsters (<Emphasis Type="Italic">Phodopus sungorus</Emphasis>)

The effect of long-term exposure to natural excretions of the European polecat on the morphological parameters and hormonal status of adult male Campbell hamsters (Phodopus campbelli) and dwarf hamsters (Ph. sungorus) was studied. Exposure to volatile components of natural excreta of a potential predator did not have any significant effect on hamsters. The combined influence of volatile and nonvolatile components of the polecat’s excretions caused physiological stress in Ph. campbelli, while in Ph. sungorus, on the contrary, an increase in thymus weight and the plasma testosterone level was recorded.     

Chernov’s compensation principle and the effect of rodent community completeness on the variability of bank vole (<Emphasis Type="Italic">Clethrionomys glareolus</Emphasis>) population in the Middle Urals

Using methods of geometric morphometrics, significant differences have been revealed in manifestations of variability and morphological disparity in allochronous samples from the population of model species, the bank vole (Clethrionomys glareolus Schreb. 1780), in the Middle Urals at different levels of rodent community (taxocene) completeness in different years. Two states of the taxocene—oligospecific (two species) and polyspecific (five species)—and the level of relative abundance of bank voles (high or low) have been taken into account. Comparative analysis of variation in the size and shape of the mandible in same-aged (late-summer) young of the year has shown that significant morphogenetic differences exist between the animals sampled from the rodent taxocene at its different states (oligospecific and polyspecific) and, to a lesser extent, at high and low levels of abundance. The level of variation and the parameter of intragroup morphological disparity (MNND) in the mandible shape reach a maximum when the community has a reduced composition and decrease to a minimum when its composition is complete (i.e., in the oligo- and polyspecific taxocene). A parallelism is observed in the manifestation of morphofunctional changes of the mandible in male and female voles under conditions when the taxocene has high abundance and oligospecific composition or low abundance but polyspecific composition. Different morphogenetic responses of the population to oligo- and polyspecific composition of the community are considered as a compensatory increase of morphological disparity in the dominant species (the bank vole) under conditions of incomplete composition of the taxocene and low population density, in accordance with Chernov’s ecological compensation principle.     

Tree vegetation of the forest-tundra ecotone in the Western Sayan mountains and climatic trends

Parameters of reproduction of the Siberian stone pine (Pinus sibirica), including radial and apical tree increments, the age structure of stands, the amount of young growth, and its distribution along an altitudinal gradient, have been studied in the forest-tundra ecotone of the Western Sayan. The results show that, over the past 30 years, P. sibirica undergrowth has expanded to the mountain tundra belt, the apical and radial tree increments and stand density have increased, and the life form of many P. sibirica plants has changed from prostrate to erect (single-or multistemmed). These changes correlate with the dynamics of summer temperatures and monthly (in May and June) and annual precipitation. The rise of summer temperatures by 1°C promotes the expansion of P. sibirica undergrowth for approximately 150 m up the altitudinal gradient.     

Latitudinal variation in size of freshwater pulmonate mollusks (Mollusca: Gastropoda: Pulmonata) in Western Siberia

The size of shells in some freshwater pulmonate mollusk species abundant in Western Siberia (Lymnaea fragilis, L. terebra, Planorbis planorbis, and Anisus leucostoma) is relatively large in the south and decreases in the north. It is supposed that this phenomenon is explained by the fact that the season with conditions allowing the growth of mollusks is shorter in the north than in the south of Western Siberia.     

Ecological and ethological characteristics of <Emphasis Type="Italic">Sylvia</Emphasis> warbler colonies in patchy habitats on the courland spit,Baltic Sea

Territorial and nesting behavior of Sylvia warblers in a patchy environment has been studied. The results show that shortage of nesting sites and consequent high population density result in acute social strain. Under such conditions, changes are observed in species-specific forms of this behavior, which provide for the maximum possible realization of individual reproductive potential.     

Seasonal dynamics of heart rate variability in three murine rodent species

Seasonal dynamics of heart rate variability in individuals of late summer and autumn generations have been studied in three rodent species kept in a vivarium: the striped field mouse (Apodemus agrarius), bank vole (Clethrionomys glareolus), and northern red-backed vole (Cl. rutilus). It has been shown that the cardiac function of the rodents in autumn and winter is mainly controlled by autonomic mechanisms: the heart rate is slow, cardiovascular control systems are relaxed. During the winter-spring transition, the role of central cardiovascular circuits increases because of the necessity to activate all body systems by spring.     

The Spatiotemporal Structure of Rodent Populations in the Steppe Zone of Western Siberia

The spatial structure of populations has been studied in two rodent species inhabiting the subzone of meadow steppes of the steppe zone of Omsk oblast: the narrow-sculled vole (Microtus gregalis Pall.) and steppe lemming (Lagurus lagurus Pall.). Their populations are represented by combinations of territorial family groups whose structure and spatial distribution vary by season depending on population density, the phase of the population cycle, and the status of their members in the population. In the areas cohabited by M. gregalis and L. lagurus, the pattern of territory use and the rhythm of animal activity during the day depend primarily on their total density: under conditions of low density, the population groups of both species are spatially separated; at increased density, they are distributed with respect to the pattern of daily activity. Both species jointly use part of the territory but at different times of day: M. gregalis, mainly at night and in the morning; L. lagurus, in the daytime.