ISSN 1022-7954, Russian Journal of Genetics, 2014, Vol. 50, No. 3, pp. 274–279. © Pleiades Publishing, Inc., 2014. Original Russian Text © Yu.V. Slynko, V.V. Stolbunova, S.V. Chebotar, V.V. Zamorov, A.N. Gurovskiy, 2014, published in Genetika, 2014, Vol. 50, No. 3, pp. 314–320. 274 INTRODUCTION The main paradox of biological invasions is that, despite the existence of founder and bottleneck effects, the level of genetic diversity in new popula- tions is usually not lower, and is often higher, than in donor populations [1, 2]. One of the basic assumptions allowing for an explanation of this paradox concerns the high level of genetic diversity in donor populations and the spatial-temporal multiplicity of the invasions [3, 4]. Such diversity, especially in the presence of a large number of rare variants, creates the prerequisites for sustainable adaptation to new habitats, even with a small number of invaders [5]. For successful invasion, it is essential that the invading species is characterized by a close relationship of genotypic and phenotypic variability, especially the variability of plastic charac- ters [5, 6]. The round goby (Neogobius malanostomus (Pallas)) is one of the fish species endemic to the estuarine brackish water complex of Ponto-Caspian Basin, which is most widely distributed in freshwater ecosys- tems [7–11]. The natural range of the round goby includes the basins of the Black, Marmara, Azov and Caspian seas, as well as the lower reaches of the rivers flowing into them [12]. Since the last two decades of the 20th century, this species successfully spread over almost all of the river basins of Ponto-Caspian drain- age (Danube, Dniester, Dnieper, Don, and Volga riv- ers). Via the system of channels, the round goby pene- trated and settled in the bays and the river and lake basin ecosystems of Baltic Sea. With the ballast water of the ships, this species was introduced and formed large populations in North America (the Great Lakes basin). Such massive expansions of the round goby stimulated active genetic studies of this species in the native part of the range, as well as in newly invaded water bodies. Based on the analysis of the mtDNA and microsatellite loci, it was demonstrated that the spe- cies of interest was characterized by a high level of genetic variation [13–16]. Specifically, at the main phylogeographic marker, the mtDNA cyt b locus, a total of >80 haplotypes were described. Moreover, it was demonstrated that the highest haplotype diversity was typical for populations of the Black Sea basin. As it was established, these populations became the major sources of origin of the majority of the populations of the Baltic basin and the Great Lakes basin of the United States. The objective of this study was to examine haplo- type diversity in the mtDNA cyt b gene fragment in populations of the round goby from the estuaries and bays of the northwestern part of the Black Sea basin. MATERIALS AND METHODS The fragment of the mtDNA cyt b locus was exam- ined in eight population samples (consisting of five specimens each) of round goby (N. melanostomus) from the estuaries, lakes, and bays of the northwestern part of the Black Sea and the waters of Snake Island (four specimens). In total, 39 individual specimens were examined (Fig. 1). Muscle samples were taken from pre-frozen fishes and immediately used for DNA extraction. Total DNA was extracted using the Haplotype Diversity in the mtDNA cyt b Gene in Round Goby (Neogobius melanostomus (Pallas)) from the Northwestern Part of the Black Sea Basin Yu. V. Slynko a , V. V. Stolbunova a , S. V. Chebotar b , V. V. Zamorov b , and A. N. Gurovskiy c a Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl oblast, 152742 Russia e-mail: syv@ibiw.yaroslavl.ru b Department of Hydrobiology, Department of Genetics, Odessa Mechnikov National University, Odessa, 65058 Ukraine c Department of Zoology, Voronezh State University, Voronezh, 394000 Russia Received June 11, 2013; in final form, October 9, 2013 Abstract—To study the genetic causes of successful biological invasion, haplotype diversity in the mtDNA cyt b locus was examined in populations of the round goby Neogobius malanostomus (Pallas): (Gobidae, Piscs) from the Black Sea basin, which is considered to be the main source of irruption. It was demonstrated that the haplotype diversity of this species was much higher than was assessed earlier. At the population level, a statistically significant association of haplotype diversity with the individual variation of plastic characters was established. DOI: 10.1134/S1022795414030090 ANIMAL GENETICS