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S. V. Mezhzherin, S. V. Kokodiy, P. P. Pukhtaevitch and A. V. Kulish

Abstract

Study of population structure of crucian carps in the mixed forests zone of Northern Ukraine (characterized by ample diversity of unregulated aquatic systems) showed the presence of diploid C. carassius and C. auratus, triploid C. gibelio (represented by a series of clones), C. auratus × C. carassius diploid hybrids, and tetraploid hybrids between C. carassius and C. gibelio. The crucian carps of the region compared with those of more southern zones of Ukraine are characterized by numerical prevalence of unisexual form of C. gibelio, and relatively restricted hybridization of C. carassius and C. auratus.

Open access

S. V. Mezhzherin and O. V. Vernygora

Abstract

Migratory stocks of shads passing through the Kerch strait during their seasonal migrations consist of three groups of specimens, that can be identified based on the number of gill rakers on the first arch. These are so called Kerch shad A. maeotica (50.2 %), Pontic shad A. immaculata (48.7 %) and Caspian shad A. caspia (1.1 %). This ratio of species in the region remains stable for the last 60 years. Populations of Kerch and Pontic shads have similar age structure and sex ratio with a shift toward females 52-54 %. Specimens of A. maeotica have greater linear size and weight than those of A. immacuta, that indicates higher growth rate of the former. Analysis of 26 body measurements shows definite differences between these shads in their absolute features, there are also some differences in the proportions of the head. Nevertheless, degree and reproducibility of interspecific differences during various periods of time, do not allow for the reliable discrimination of specimens of these species assumed by some researchers

Open access

S. V. Mezhzherin, T. V. Salyy and A. A. Tsyba

Abstract

Comparison of reproductive parameters in several Cobitis forms with different ploidy shows that the maximum fertility is found in diploid Cobitis, the triploids are less fertile and the tetraploids even less fecund. The latter reach maximum values of size and weight indicators but minimum number of eggs, the smallest size of the ovaries but the biggest eggs. Nevertheless, the combined reproductive potential of polyploid females is higher than of diploid spiny loaches with equal ratios of males to females in populations. The obvious reasons for the successful expansion of polyploid individuals of the spiny loaches are both their higher fertility at the population level and the changes in environmental conditions associated with the regulation of all major rivers in Ukraine in the 1960-1970s.

Open access

S. V. Mezhzherin, V. S. Kostyuk, A. V. Garbar, E. I . Zhalai and P. S. Kutishchev

Abstract

Allozymic, karyological and morphological analyzes confirmed the presence of the Thick-clawed crayfish, Astacus pachypus (Rathke, 1837), in Ukraine. Th is rare species in Ukraine is found only in two small adjacent localities restricted to the Lower Dnieper. It is characterized by a unique set of chromosomes (2n = 116) and a distinct pool of allozymes, allowing, together with morphological features, to clearly distinguish it from the other three species of the Ukrainian fauna.

Open access

V. S. Kostyuk, A. V. Garbar and S. V. Mezhzherin

The existence on the territory of Ukraine of two sympatric widespread species definitely different by their chromosome number was proved based on the meiotic chromosome preparations. Besides the nominal species Pontastacus leptodactylus (Dana, 1852) with modal haploid chromosome number n = 93 we prove the existence of P. angulosus (Rathke, 1837) with n = 88.

Open access

S. V Mezhzherin, P. P Pukhtayevych and А. А Tsyba

Abstract

In the rivers of the Northern Ukraine by meams of karyological and allozyme analysys obtained extensive natural hybridization between Cobitis taenia and Sabanejewia aurata, initially leading to the formation of diploid hybrids. Besides that certain water bodies are predominantly populated by triploids of the C. taenia - C. tanaitica - S. aurata biotypes. Since the share of this kind of hybrid biotypes significantly exceeds the number of individuals of S. aurata, it is concluded that the hybridization of a common and eurybiontic C. taenia with rarer stenobiontic S. aurata, is of absorbing character.

Open access

V. Tytar, S. Mezhzherin and L. Sobolenko

Abstract

Maximum entropy niche modeling was employed as a tool to assess potential habitat suitability for 13 amphibian species and to map their potential distribution in the Western Podillya (Ukraine). The predictor variables used were of climate, topography and human impact (assessed by the Human Footprint). The “mean temperature of coldest quarter” and “isothermality” were two of the most important factors in predicting habitat suitability and distribution. Another profound contribution has been displayed by the Human Footprint, meaning that human infrastructure may benefit amphibians, a phenomenon that perhaps is much more widespread than thought. Areas have been distinguished that in the first place should be of interest to nature conservationists targeting amphibians (exemplified by Bombina variegata) and a map summarizing species richness was produced.

Open access

S. V. Mezhzherin, L. M. Yanovich, E. I. Zhalay, L. A. Vasilieva and M. M. Pampura

Abstract

Genetic and Morphological Variability and Diff erentiation of Mussels (Bivavia, Unionidae, Anodontinae) in Ukraine. Mezhzherin S. V., Yanovich L. M., Zhalay Е. I., Vasilieva L. А., Pampura М. М. - Th e study of allozymes variation and sequence analysis of two mitochondrial genes supports the concept that there are four species of subfamily Anodontinae in the Eastern European fauna, three of them; Anodonta cygnea Linnaeus, 1758; A. anatina Linnaeus, 1758; Pseudanodonta complanata (Rossmassler, 1835) are indigenous and one is invasive (Sinanodonta woodiana Lea, 1834). Th is paper analyzes morphological diagnostic features of which some can be used in identification of these species.

Open access

S. V. Mezhzherin, E. I. Lashkova, I. I. Kozinenko, A. V. Rashevskaya and V. M. Tytar

Abstract

Based on the maximum entropy modeling algorithm and using 12 environmental variables, we modeled the distribution of the vole twin species Microtus arvalis and M. levis, with particular attention to regions where the species overlap. For both species models performances were considered “excellent” (AUC > 0.9), although some occurrences appeared in areas of low habitat suitability, whereas in some areas of predicted high habitat suitability there were no occurrences. Apparently, both species do not fully occupy areas predicted to be favorable in terms of habitat suitability and persistence. Th e cause for such restriction are not the considered factors (including bioclimatic), but competitive interactions that prevent individuals of one species from expanding within the home range of the other. Contributions of the considered environmental variables for generating the potential distribution prediction were distinguished: for M. arvalis net primary production alone made the largest contribution (42 %), whereas for M. levis there was a cumulative effect of a number of factors.

Open access

V. Tytar, L. Sobolenko, O. Nekrasova and S. Mezhzherin

Abstract

Using Ecological Niche Modeling for Biodiversity Conservation Guidance in the Western Podillya (Ukraine): Reptiles. Tytar, V., Sobolenko, L., Nekrasova, O. Mezhzherin, S. - Maximum entropy niche modeling was employed as a tool to assess potential habitat suitability for 10 reptile species and to map their potential distribution in the Western Podillya (Ukraine). We used climate, topography and human impact (assessed by the Human Footprint) as predictor variables. “Isothermality”, “temperature seasonality” and the “mean temperature of coldest month” were three most important factors in predicting habitat suitability and distribution. A profound contribution to the modeling has been displayed by the Human Footprint, meaning that human infrastructure may benefit reptile species. Areas have been distinguished that in the first place should be of interest to biodiversity conservationists targeting reptiles and maps summarizing predicted habitat suitability and species richness were produced for guiding conservation efforts.