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  • Author: S. V Mezhzherin x
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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.

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.

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

Abstract

The analysis of present-day crucians’ settlements in water systems of Eastern Ukraine designated the predominance of the digeneous Goldfish, C. auratus, in the region, the number of which made 78.7 %, from the total number of the examined representatives of the genus. The second group consists of gynogenetic Prussian carps, C. gibelio (14.3 %); it is represented by the clone biotype and recombinant individuals. Crucian carp, C. carassius (3.6 %), turned out to be rare and its number did not exceed the number of the caught hybrids C. auratus × C. carassius (3.4 %). The retrospective analysis of literature data and museum collections gave an opportunity to describe the changes in species composition of the genus which took place during the last 150 years. Within this period the crucian carp, which used to be the single and most common representative of genus Carassius (Jarocki, 1822) in the region, became nearly an extinct species. In the meanwhile the representatives of the group of species of Prussian carps, C. auratus + C. gibelio, which appeared in the region in the late 1960s, rapidly increased their number and became the most numerous fish of the Eastern Ukraine. The discovered tendency is not unique for the researched region; in general it reflects the European tendency for the crucian species. The reasons for that are rivers’ regulation and destruction of bottomland ecosystems. The secondary factors for the elimination of C. carassius are the competitive relations of individuals representing both species and easy hybridization, during which the more numerous species C. auratus absorbs the rare C. carassius.

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.

Abstract

The Steppe mouse, Mus spicilegus, is endemic to Europe and found to be expanding its home range in recent years. In Ukraine there are indications a north- and eastwards expansion and/or reestablishment of M. spicilegus. We suggest that climatic conditions may be the primary factors that foster or limit the range expansion of M. spicilegus in Eastern Europe. Our objective was to complement the knowledge about the distribution of the species with an estimation of the potential distribution of the species in Ukraine using known occurrence sites (in Ukraine and neighbouring areas) and environmental variables in an ecological niche modelling algorithm. After accounting for sampling bias and spatial autocorrelation, we retained 73 occurrence records. The algorithm used in this paper, Maxent (Phillips et al., 2006), is a machine learning algorithm and only needs presence data, besides the environmental layers. Using this approach, we have highlighted the importance and significance of a number of bioclimatic variables, particularly those characterizing wintering conditions, under which higher mean temperatures enhance habitat suitability, whereas increased precipitation leads to an opposite effect. The broadly northwards shift of the home range of the species in Ukraine could generally be due to the increasing (since the 1980s) mean temperature of the winter season. We expect this expansion process will continue together with the changing climate and new records of locations of the species may be used for monitoring such change.

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.

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.

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.

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.