Interspecific interactions of amphipods <Emphasis Type="Italic">Gammarus lacustris</Emphasis> and <Emphasis Type="Italic">Gmelinoides fasciatus</Emphasis>

Experimental studies of interactions between two amphipod species (Gmelinoides fasciatus and Gammarus lacustris) showed that predation is the basic mechanism accounting for their mutual exclusion in nature. Mortality from predation among similar-sized specimens of both species at an equal abundance ratio was similar (24–25% in G. lacustris and 27–30% in G. fasciatus). The displacement of G. lacustris by G. fasciatus was observed when the latter was dominant. Adult G. fasciatus and G. lacustris successfully preyed on juveniles of their competitors and did not differ significantly in daily food consumption as a percentage of body weight: 6–24% at a fresh body weight of 18–24 mg in both species. The potential for rapid population growth under new conditions contributed to the success of the invasive Baikal species G. fasciatus in displacing G. lacustris from many water bodies of Russia.     

The role of rapid induced resistance of host plant in trophic interactions between <Emphasis Type="Italic">Betula pendula</Emphasis>, <Emphasis Type="Italic">Lymantria dispar</Emphasis>, and <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>

Life history traits of gypsy moth larvae markedly decrease under the effect of host plant insect resistance, but no significant changes occur in immunity parameters such as hemolymph phagocytic activity and lysozyme-like activity of hemolymph plasma and midgut tissue; moreover, alkaline protease activity in the midgut contents becomes higher. The actual sensitivity of the larvae to Bacillus thuringiensis remains unchanged.     

Analysis of rodent populations in technogenically transformed areas (with reference to <Emphasis Type="Italic">Apodemus</Emphasis> (<Emphasis Type="Italic">S.</Emphasis>) <Emphasis Type="Italic">uralensis</Emphasis> from the EURT zone)

It is shown that the response of rodent populations to acute and chronic irradiation depends on its functional structure, i.e., on specific features of animals with two alternative types of ontogenetic development. Upon acute irradiation, sexually immature young of the year (animals with the second type of ontogeny) are most radioresistant. Exposure to chronic irradiation, as in the zone of the Eastern Ural Radioactive Trace (EURT), leads to an increase in the proportion of mature young of the year (animals with the first type of ontogeny), which are the most radiosensitive part of the population. The abundance and fecundity of mice in the impact zone are consistently higher than in the background zone, which improves the adaptive potential of the population. The role of species ecological specialization and configuration of the contaminated zone in the formation of migrant rodent population is emphasized. It is concluded that a high migration activity allows the pigmy wood mouse (a radiosensitive species) to avoid long-term radiation exposure.     

Traditional management and conservation of shea trees (<Emphasis Type="Italic">Vitellaria paradoxa</Emphasis> subspecies <Emphasis Type="Italic">nilotica</Emphasis>) in Uganda

Traditional practices are universally recognised as a basis for conservation of biodiversity. However, such practices are often not included in natural resource conservation policies. This study assessed local conservation practices of shea trees (Vitellaria paradoxa) within different farming systems in Uganda and developed conservation guidelines for the species. The assessment involved 300 respondents, 15 focus groups and 41 key informants. Content analysis was used to identify the most important management and conservation practices. Local uses were categorised on the basis of shea tree products while differences in conservation practices were analysed using the Friedman test. The results show that eight shea tree products are used for 36 different purposes. Respondents’ age significantly influenced their knowledge about the shea tree. Traditional conservation practices include on-farm retention during cultivation and the use of folklore (mainly taboos), customs and rituals. Traditional management practices include weeding, bush burning, pollarding and pruning. Based on the current management and traditional conservation practices, a framework for the conservation of shea trees is proposed for integration into conservation policy decisions.     

Combined influence of food level and inoculation density on competition between <Emphasis Type="Italic">Anuraeopsis fissa</Emphasis> and <Emphasis Type="Italic">Brachionus patulus</Emphasis> or <Emphasis Type="Italic">Brachionus macracanthus</Emphasis> (Rotifera: Brachionidae)

We tested separately the effect of two taxonomically related rotifers (B. patulus and B. macracanthus) on the population dynamics of another species (A. fissa) at low (0.5 ×10 ⁶) and high food levels (1.5 × 10⁶ cells/ml of Chlorella vulgaris) using different inoculation densities (0–100%). We also quantified the impact of A. fissa on the two brachionid species. Regardless of the presence of the competing species, an increase in the availability of food led to increase in the abundances of the three rotifers. The population growth of B. patulus, B. macracanthus, or A. fissa was affected negatively when cultured together with another species. An increase in the initial density of any one of the competing species became advantageous to maintain a certain population size. At a low algal food level, B. patulus was able to suppress A. fissa more strongly than B. macracanthus. On the other hand, at a high food level, B. macracanthus suppressed the population of A. fissa more strongly than B. patulus. Peak population densities for A. fissa varied from about 150 to 1000 ind./ml, depending on food density and the presence of competitors. The rate of population increase (r) of A. fissa, B. patulus, and B. macracanthus increased with an increase in food availability but decreased with increasing initial density of the competitor. Both Brachionus spp. experienced negative growth rates in the presence of A. fissa, especially at a high initial density of the latter. Published in Russian in Ekologiya, 2007, Vol. 38, No. 5, pp. 381–390. The article was submitted by the authors in English.     

Genetic differentiation of <Emphasis Type="Italic">Pinus mugo</Emphasis> Turra and <Emphasis Type="Italic">P. sylvestris</Emphasis> L. populations in the Ukrainian Carpathians and the Swiss Alps

The allozyme analysis of six local populations of Pinus mugo Turra and six populations of P. sylvestris L. in the Ukrainian Carpathians, Swiss Alps, and Schwarzwald has shown a higher polymorphism and greater interpopulation differentiation of the Carpathian group of P. mugo populations compared to the Alpine group (Nei’s genetic distance DN ₇₈ at the level of geographic population group is −0.023). A genetic differentiation of DN ₇₈ = 0.049 between these populations, which are isolated by a distance of more than 1000 km, has been found. This confirms the existence of the subspecies P. mugo ssp. mugo and P. mugo ssp. uncinata in the Carpathians and Alps, respectively. The hypothesis is put forward that the former subspecies has been formed in the Balkans and the latter, in the Pyreneans. It has been demonstrated that regional populations and geographic groups of P. sylvestris are less differentiated than those of P. mugo.     

Effect of temperature and precipitation on linear increment of <Emphasis Type="Italic">Sphagnum fuscum</Emphasis> and <Emphasis Type="Italic">S. magellanicum</Emphasis> in Western Siberia

The linear increment of Sphagnum fuscum and S. magellanicum in ombrotrophic mires of Western Siberia has been measured during two years over a transect about 2500 km long extending from forest–steppe to forest–tundra. Along the latitudinal gradient, the increment of both species has proved to be correlated with annual average air temperature and, in S. magellanicum, also with annual precipitation. The determinants of their growth differ between the southern, central, and northern parts of the study region. At the regional level, the annual and summer precipitation plays a more important role than the average air temperature. The increment of S. fuscum in the southern part is positively correlated with the amount of precipitation and negatively correlated with summer temperature, whereas the situation in the central part is inverse. In S. magellanicum, the linear increment is directly dependent on the annual average temperature and annual and summer precipitation in the south and on the annual and summer precipitation in the north of Western Siberia. The dynamics of linear growth of both species in bog pine forests during the growing season are similar: its rate is the highest in June, when the linear increment of S. fuscum and S. magellanicum amounts to 60 and 85% of the annual total, respectively.     

Intrapopulation spatial segregation in bream (<Emphasis Type="Italic">Abramis brama</Emphasis>) and roach (<Emphasis Type="Italic">Rutilus rutilus</Emphasis>) in the Rybinsk Reservoir

In the course of studies on mass fish species (bream and roach) in water bodies of the Upper Volga basin, intraspecific groups of individuals have been distinguished. Conditions and possible mechanisms of spatial differentiation of these groups are considered. The intrapopulation divergence of individuals by some adaptive characters, primarily behavioral, enables them to utilize alternative resources, which provides for more efficient use of the environment by populations.     

Photosynthetic and biochemical characteristics of invasive species (<Emphasis Type="Italic">Ambrosia artemisiifolia L., Ambrosia trifida L.</Emphasis> and <Emphasis Type="Italic">Iva xanthifolia Nutt.</Emphasis>) depending on soil humidity and phenological phase

Environmental factors like temperature and soil humidity are recognized as influencing factors on photosynthetic response and organic productivity, distribution and biochemical characteristics of plants. Here we present measurements of gas exchange parameters, water-use efficiency (WUE) and nitrogen-use efficiency (NUE) of field-grown invasive species Ambrosia artemisiifolia L., Ambrosia trifida L. and Iva xanthifolia Nutt., in order to define their potentials as colonizers. Biogenic volatile organic compounds (BVOC) in leaves and flowers depending on soil humidity were also investigated.     

Changes of leaf morphology in <Emphasis Type="Italic">Betula pendula</Emphasis> roth and <Emphasis Type="Italic">B. pubescens</Emphasis> Ehrh. along a zonal-climatic transect in the Urals and Western Siberia

Leaf size, shape, and parameters of venation in Betula pendula and B. pubescens have been studied along a 1600-km latitudinal zonal transect in the Urals and Western Siberia. The results show that leaf size and venation density depend on the geographic location of population, with these parameters in the two species changing in opposite directions along the transect. In its northern part (forest tundra-southern taiga), B. pubescens shows a positive correlation of leaf area with long-term-average air temperature, while this correlation in B. pendula is negative. In the southern part, correlations of leaf size with long-term average precipitation in the two species are also opposite in sign. Parameters of leaf shape in both species depend mainly on weather conditions in the current year rather than on long-term average climatic parameters. The conclusion is drawn that B. pendula and B. pubescens have different mechanisms of structural adaptation of leaves to climate and weather conditions that are based on changes in leaf size and shape.     

Mating systems in the steppe lemming (<Emphasis Type="Italic">Lagurus lagurus)</Emphasis> and narrow-skulled vole (<Emphasis Type="Italic">Microtus gregalis</Emphasis>) from the Northern Kulunda Steppe

A comparative analysis of reproductive behavior has been performed in the steppe lemming (Lagurus lagurus) and narrow-skulled vole (Microtus gregalis). The results show that the species are similar in certain behavioral features indicative of the stability of mating pairs. However, in the narrow-skulled vole, unlike in the steppe lemming, mature males in olfactory tests show preference for receptive sibling females versus non-kin females. Probably, it is the absence of the incest taboo that allows the involvement of young of the year in reproduction within growing family groups and accounts for “coloniality” of the species.     

Group effect on individual locomotor activity of common toad (<Emphasis Type="Italic">Bufo bufo</Emphasis> L.) and brown frog (<Emphasis Type="Italic">Rana temporaria</Emphasis> L.) tadpoles

Different components of group effect on the locomotor activity of single common toad and brown frog tadpoles have been studied by estimating the length of their trajectories, the speed of movement, the number of crossings of experimental field zones, and the number and duration of stops. The results show that toad tadpoles are more active than frog tadpoles. Conspecific metabolites added to the water do not change the pattern of their locomotor activity. Under conditions of visual contact with other tadpoles, locomotor activity of a toad tadpole decreases, whereas that of a frog tadpole increases. Thus, tadpoles of the two amphibian species show species-specific behavioral responses to changes in experimental conditions.     

Variability of biochemical parameters and radiation resistance of the seed progeny of <Emphasis Type="Italic">Descurainia sophia</Emphasis> and <Emphasis Type="Italic">Lepidium apetalum</Emphasis> under exposure to various factors

The physiological and biochemical characteristics of seedlings of Descurainia sophia (Fisch.) and Lepidium apetalum Wild. have been used as examples to demonstrate that long-term exposure of plant populations to environmental stress factors causes adaptive changes in antioxidant and genomic systems that may considerably affect the radioresistance of seed progeny. The resistance to additional acute irradiation of seed progeny of wild plants adapted to different environmental conditions has been found to be determined not only by the combination of antioxidant and DNA-repair protection systems and the vulnerability of the functioning genome, but also by their variability. The data on the relationship of the radioresistance of wild plant populations with physiological and biochemical characteristics and their variability may be used for expert environmental assessment of the state of the biota and prediction of its viability under exposure to abiotic environmental factors.     

Species composition and quantitative representation of fishes in biotopes with the riffle minnow <Emphasis Type="Italic">Alburnoides bipunctatus</Emphasis>

Species composition of fishes was studied in rivers (capture sites) inhabited by the riffle minnow. In some localities, this species proved to occupy a leading position in the ichthyofauna, being obviously dominant. In small rivers, 16 species were caught together with it, including seven species regularly occurring in catches. The relative abundance of riffle minnow showed a moderate positive correlation with that of the gudgeon (0.568) and a nonsignificant negative correlation (?0.399) with that of the bleak. It is probable that the population dynamics of riffle minnow are determined mainly by natural intraspecific mechanisms rather than by water quality, which has changed only slightly in the rivers studied.     

Seasonal variation of the forewing in polyvoltine whites <Emphasis Type="Italic">Pieris rapae</Emphasis> L. and <Emphasis Type="Italic">P. napi</Emphasis> L. (Lepidoptera: Pieridae) in the forest-steppe zone of the Southern Urals

The seasonal variation of forewing size and shape was analyzed in adults of different seasonal generations of two polyvoltine species of whites: Pieris rapae and P. napi (Lepidoptera: Pieridae). Particular morphological features of the forewing are characteristic of each seasonal generation of adults independently of their sex and species. Adults of the spring generations have the smallest wings, elongate and pointed. Adults of the summer generation have the largest, broad and rounded wings over the entire summer season. Adults of the autumn generation have wings similar in shape and size to those of the summer generation, but somewhat smaller and more elongate. Differences between seasonal generations in forewing shape are linked to differences between adults of each generation in adaptation to dispersal.