Том 45, № 8 (2018)

The diet of a symbiont, Brandtia parasitica parasitica (Dybowsky 1874), of Baikal sponges collected during an ecological crisis in the littoral zone of Lake Baikal is analyzed. In June 2015, the main components of the diet of the amphipod that lived on diseased sponges were fine detritus, sedimented chrysophycean algae of the genus Dinobryon, and planktonic diatoms of the genus Synedra. These algae dominate in phytoplankton in the southern part of Baikal during the study period. Abundant blue-green algae were present on the surface of diseased sponges, but B. p. parasitica did not feed on these algae. As toxins secreted by blue-green algae are known to render a negative effect on hydrobionts, mass overgrowth of sponges with blue-green algae should reduce the population of the symbiotic amphipod.

Based on recordings, the time-frequency characteristics and repertoire size of the advertising song were studied comparatively in several leaf warblers (Phylloscopus) and reed warblers (Acrocephalus) from mainland and island populations. No significant variations in repertoire size were found between mainland and island populations, but clear differences were revealed in the frequency and time parameters of the song between the Sakhalin and continental populations. In all of the species studied, the differences are displayed in a similar way. In the Sakhalin population, the frequency range is wider than in the mainland. Possible reasons for this expansion are discussed: (1) the impoverishment of the species composition of ornithocomplexes, (2) the effect of high air humidity, and (3) the effect of specific characteristics of the vegetation cover.

We analyzed the variations in the demographic and morphological characteristics of mature Rana arvalis individuals from natural and transformed habitats near Surgut. Female frogs from the transformed habitat were significantly smaller than males and significantly younger and smaller than females from the natural habitat. The direction of sex-related differences in both populations was the same as in most of the populations of the species that had been studied earlier. The low values of the mean body length (but not age) that were recorded in populations living near the northern range limit correspond to the general trend of body size variation in adult frogs in relation to the length of the season of activity throughout its vast range. Sex-related differences in most of the studied characteristics were due only to the variations in body size; few characteristics are not dependent on the body size, and these characteristics are most likely to determine mating success in males. We observed no morphological differences related to different environmental conditions in both neighboring populations. The relative femur and shin lengths were significantly larger in males than in females not only in the two Surgut populations but in all other populations studied earlier; these differences were not related to the greater body length in males. A tendency toward an increase in the relative head width and a decrease in the relative femur and shin lengths from the southern to the northern populations was observed in both sexes; this tendency was related to neither the mean age nor the body length.

Eleven sables were captured in Sverdlovsk oblast, at distances of 133 to 203 km from the southwestern boundary of the species range, in 2014–2016. The capture sites were located within the species range of the pine marten. A brief description of the animals, photographs, morphometric data, and a map of capture sites are provided. Violation of the species range boundaries is enabled by local predominance of one species over another with regard to population size. An example of a female tagged in the Pechoro-Ilychskii Nature Reserve and caught a year later near the town of Karpinsk, 233 km from the tagging site, is given.

Five of the seven modern species of the family Anomaluridae have been studied. Significant intergeneric differences in the structure of the tongue between Anomalurus and Idiurus have been identified. These differences affect even such taxonomically important features as the number of circumvallate papillae (three in Anomalurus and two in Idiurus) and the distribution pattern of fungiform papillae. A parallel interspecific variability has been observed within the genera. It manifests itself in a decrease in the total number of fungiform papillae. The tongue structure in Anomalurus corresponds to the generalized version, initial for the order, whereas in Idiurus, it has clear signs of morphological and functional specializations.

The fecundity, fertility, and fitness of house mice from Transcaucasian populations have been investigated in laboratory conditions. We interpret our data in accordance with Milishnikov’s hypothesis (2004) that the ancestral form might have come from Transcaucasia. It is genetically close to Mus musculus s. str. and has kept a relict gene pool. The already differentiated M. musculus and M. domesticus have been introduced into this region as well. All three forms have crossed with one another, resulting in a very complicated hybrid zone formed in Transcaucasia. In our experiment, house mice from Moscow and Moscow oblast and from the hybrid zone of Transcaucasia were characterized by a similar reproduction rate. Reproduction indices weren’t significantly differ in different variants of crossings of mice from Transcaucasia with M. musculus as well as in hybrids from direct and back crosses and in backcrosses. Nevertheless, these rates differed significantly from those in M. musculus and Transcaucasian mice. In some cases, the mortality of the young was relatively high. The data obtained disagree with the presumed reduced fitness of house mice in Transcaucasia. No serious evidence has been obtained for the presence of postcopulative isolating mechanisms contributing to separation of mice from Transcaucasia from M. musculus. The results of these studies are consistent with the assumed kinship of house mouse populations of Transcaucasia and M. musculus.

The ratio between ungulates as potential victims and wolves as the main predators has been studied in different parts of the Caucasian Nature Reserve: northern, eastern, and southern. The optimum ratio of ungulates to wolves is shown to have been shifted during the stable period in the 1980s for a number of peripheral areas of the nature reserve totaling about 50 000 hectares in area. Following the crisis of the 1990s, these areas included not only all the peripheral sites but also some of the central parts of the nature reserve. From the point of view of a balance in the wolf–ungulate system, at present the functioning of the ecosystem is close to natural at no more than one-third of the territory. One of the main reasons for this is the intensification of anthropogenic economic activities of various kinds just at the borders of the nature reserve and their inevitable impact on the protected ecosystems.

Studies of the intertidal benthos of the water area of the Vitino Specialized Marine Oil Port using typical hydrobiological methods were carried out for more than ten years. From the analysis of the structure of intertidal communities using different mathematical methods, a quasi-cyclic dynamics of their biomasses was found. The dynamics of the main features of the intertidal blue mussel bed was found at one particular sampling site. In addition, some analytical approaches to the expert assessments of the state of sea floor ecosystem are discussed specifically regarding the diagnostics of the anthropogenic influence. It was shown that a single sampling cannot serve as reliable assessment due to permanent quasi-cyclic processes taking place in the intertidal communities, and the applied methods based on a sampling taking into account the shifting alongside K-, r-axis should be used only with great precaution. Long-term monitoring is needed to make the proper conclusions. The number of samplings at each station should be set in a way that can help outweigh the aggregated distribution of particular species.