Victor P. Vasilev

Further studies of mitochondrial genome variability in Ponto-Caspian Proterorhinus species (Actinopterygii: Perciformes: Gobiidae) and their taxonomic implications

Background. A new taxonomy of tubenose gobies of the genus Proterorhinus has been proposed recently. However, some of taxonomic hypotheses have not been confirmed by recent genetic studies or seem not to cor- respond with ecological features and genetic differentiation of these fishes. The aim of this paper was to test the new taxonomy through a phylogeographic analysis of the fish from 15 sites in Southern Ukraine and Russia, through analyzing the genotypes deposited in the GenBank and to define the range of those species. Materials and methods. Fin clips were sampled from 52 specimens of tubenose gobies collected from 2003 up to 2009 in 15 localities of the Ponto-Caspian basin. Genomic DNA for amplification of mitochondrial cyt b gene fragment (about 408 bp) was extracted using the Diatom®DNA Prep 100. The haplotype MedianJoining Network was constructed using the Network 4.5.1.0. software. Results. Tubenose gobies from the Black Sea basin are represented by two euryhaline species historically dis- tributed in different areas: P. semilunaris in the north-western part of the Black Sea basin (and possibly eastern Aegean basin) and P. marmoratus in the north-eastern part. The hypothesis about freshwater and marine Black Sea Proterorhinus species seems to be not probable. The validity of endemic Crimean P. tataricus is not con- firmed, several independent findings presume it to be conspecific with P. marmoratus. Some Crimean rivers and reservoirs are populated by P. semilunaris which could spread from the Dnieper River basin through the Severo- Krymskyi channel or may be accidentally introduced. The populations from the Caspian Sea and Sea of Azov basins represent the distinct evolutionary lineage of tubenose goby. But their taxonomic state should be analyzed by further molecular genetic studies of a wide scope of Caspian samples. Conclusion. The present data on the variability of the mitochondrial cyt b gene fragment in different tubenose goby populations result in revision of some previous taxonomic hypotheses in this fish group. At the same time further molecular genetic researches of Caspian populations seem to be the main tool for future development of taxonomic conclusions.

A Unique Diploid-Tetraploid Unisexual-Bisexual Fish Complex (Pisces, Cobitidae)

The discovery of vertebrate clonal forms offered new prospects in evolutionary genetic, cytological, and ecological research, which can be divided into four major blocks: clonal form origin, cytogenetic mechanisms of clonal inheritance, clonal diversity and its sources, the ecological problems of the coexistence of clonal and bisexual forms. The important results of these studies were the following: clonal forms proved to have hybrid origin, the relationships between hybridization, unisexual reproduction, and polyploidy have been understood in the evolutionary respect. As a result, a concept of reticular speciation in vertebrates have been developed [1, 2] and the origin of even-polyploid species with restored bisexuality proved to be the final stage of this process [3, 4]. By now, about 80 forms were identified among fish, amphibia, and reptiles, which are reproduced by parthenogenesis, gynogenesis, and hybridogenesis. Unlike parthenogenesis that occurs in some groups of reptiles [5], natural gynogenesis involves males whose sperms stimulate egg development, although there is no true fertilization. Therefore, fish and amphibian gynogenetic forms inhabit the same areas as one or two closely related bisexual species from whose hybridization these forms have originated. In rare cases, the reproduction of clonal forms involves males of a third, less closely related, bisexual species. This way of clonal form reproduction leads to the development of unisexual–bisexual (clonal–bisexual) complexes, such as those indentified in the genera Poecilia , Poeciliopsis (Poeciliidae), Fundulus , Menidia (Atherinidae), Phoxinus (Cyprinidae), and Cobitis (Cobitidae) [2, 5, 6]. These complexes are diploid–diploid, diploid–diploid–triploid, and, in rare cases, diploid–triploid–tetraploid. In this study, we describe fish complexes from the genus Cobitis , in which the unisexual form is represented exclusively by tetraploid females.

From Asia to Europe across Siberia: phylogeography of the Siberian spined loach (Teleostei, Cobitidae)

We assessed the genetic variability of the Siberian spined loach Cobitis melanoleuca across its unusually broad distribution that encompasses areas greatly affected by Pleistocene glaciations. Due to extensive morphological variation among their populations, the taxonomic status of C. melanoleuca is complicated. It is unclear whether C. melanoleuca represents a single taxonomic unit or contains several species or subspecies. Our analyses showed low genetic variability in all populations without any phylogenetic structure. The absence of molecular distinctiveness indicates the conspecificity of all C. melanoleuca populations. Only a few common haplotypes shared by East Asian, Siberian and European populations were found at high frequency in the nuclear genes analysed. At the mitochondrial level, Siberian populations shared haplotypes with populations located at both extremes of the species’ range suggesting central populations as a source of current mitochondrial variability. Unimodal mismatch distributions and significant values from neutrality tests support a recent expansion of C. melanoleuca. Our time estimates suggest a postglacial colonisation of European waters around 1.0 MYA, indicating that C. melanoleuca may represent the last cobitid immigrant in Europe that used the northern route across Siberia to expand its range.

Fishes of inland waters of the Phu Quoc Island, Gulf of Thailand, Vietnam: ichthyofauna structure and some remarks on the major evolutionary trends in its genesis

Studying an island fauna offers a unique opportunity to learn about specific evolutionary trends in different groups of animals and the main features of the genesis of faunas. The comparative analysis of closely related populations living on an island and on the neighbouring mainland may bring about some clues regarding the pace of evolution at different biological levels, starting from the variability of characters and continuing in the origin of new taxa. Therefore, the islands of southeast Asia, representing the largest complex of islands in the world and housing a substantial proportion of global biodiversity (Mittermeier et al. 2004), are of the great interest for both evolutionaryand taxonomic investigators (Heaney 1986, Steppan et al. 2003, Esselstyn et al. 2009). The additional assets of some of those islands are the poorly studied faunas and the sufficiently dated geological history. The ichthyofauna of the Vietnamese Phu Quoc Island situated in the Gulf of Thailand in the proximity of the Cambodian mainland coast is one of those practically ACTA ICHTHYOLOGICA ET PISCATORIA (2012) 42 (3): 193–214 DOI: 10.3750/AIP2011.42.3.04