O. A. Radchenko

Genetic Divergence of Chars of the Genus Salvelinus from Kronotsky Lake (Kamchatka Peninsula)

Chars of the genus Salvelinus, inhabiting lakes and lake-river systems, comprise morphological and ecological forms whose taxonomic status is under dispute. In the present work, we have examined genetic variation and divergence in various chars from the Kronotsky lake basin: the lacustrine chars (white, nose, and longhead) and riverine Dolly Varden Salvelinus malma. The study was conducted using analysis of allozyme and microsatellite loci, myogens, RAPD, and restriction analysis of two mtDNA segments. The estimates of heterozygosity at allozyme and microsatellite loci were similar to the corresponding parameters in populations of northern Dolly Varden and Arctic char. Heterozygote deficit was recorded in both samples of separate forms, and in the total sample of all chars from Kronotsky Lake. For allozyme and microsatellite loci, appreciable genetic differentiation among the samples of different char forms was found, which was comparable to that among the spatially isolated populations of northern Dolly Varden. This result indicates reproductive isolation among the char forms examined. However, this isolation is not complete, because no fixed differences between the forms by any of the genetic systems analyzed were found. The genetic differentiation among different forms of lacustrine chars, which corresponds to the interpopulation rather than interspecific level, is thought to be explained by their comparatively recent divergence.

Relationships and divergence of some taxa of the subfamily Lycodinae (Zoarcidae, Pisces) based on molecular-genetic and morphological data

An integrated molecular-genetic and morphological study of 14 species of 6 genera of Zoarcidae of the subfamily Lycodinae was performed. A high coincidence of study results obtained using both methods was found. The generic independence of the genus Petroschmidtia that includes species P. albonotata and P. toyamensis was justified. It was shown that species L. schmidti and L. nigrocaudatus belong to the genus Lycogrammoides; and the generic status of the genus Bothrocarichthys with species B. microcephalus and of the genus Allolepis with species A. hollandi was restored. The studied taxa fall into three large monophyletic groups that include species of the genus Petroschmidtia, species of the genus Lycodes, and species of the genera Bothrocara, Allolepis, Bothrocarichthys, and Lycogrammoides. Taxa of the last group are characterized by a large complex of morphological differences from the first two groups, including the absence of ventral fins. A key to species and genera of Lycogrammoides and Bothrocarichthys was compiled. The problem of determination of the time of divergence of the studied zoarcid-like fish using the concept of “molecular clock” and its calibration according to paleontological and paleogeographic data is discussed.

Variation of cytochrome b gene in sympatric chars from kronotsky lake (Kamchatka Peninsula)

In previously identified sympatric char forms (species) from Kronotsky Lake (Kamchatka Peninsula) and a number of other chars from the genus Salvelinus, nucleotide sequences of the mtDNA cytochrome b gene were determined and phylogenetic analysis of these chars was performed. The divergence estimate of the cytochrome b gene in the Kronotsky char group (0.48%) coincided with the interpopulation difference estimates in northern Dolly Varden, which indicates a relatively recent divergence of the chars from Kronotsky Lake. Haplotypes of each form of the Kronotsky Lake chars are divided into two groups, which belonged to two different phylogenetic mtDNA lineages of northern Dolly Varden from Chukotka and Kamchatka. The formation of the Kronotsky char forms proved to be unrelated to the observed variability of the mtDNA cytochrome b gene.

Variability of Nucleotide Sequences of Mitochondrial DNA Cytochrome b Gene in Chars of the Genus Salvelinus

Nucleotide sequences of two (405- and 1050-bp) regions of mitochondrial DNA (mtDNA) cytochrome c gene were established in chars of the genus Salvelinus from Russian Far East and Siberia. Based on the divergence and phylogenetic analysis of nucleotide sequences of the mtDNA cytochrome b gene, S. laecomaenis was shown to carry the most ancient mitochondrial lineage, which is close to the ancestral one. The archaic mtDNA of S. levanidovi occupied an isolated position on the phylogenetic trees. The mtDNA lineage of the southern S. malma was close to the S. alpinus–S. malma malmacomplex group. Within the S. alpinus–S. m. malma complex, three groups of mtDNA types having particular geographic distributions were distinguished. The Kolyma–Chukotka group includes lake S. taranetzi, S. boganidae, andS. elgyticus from Chukotka, lake chars from Kolyma. The Okhotsk group is represented by northernS. malma, lake chars from northern Sea of Okhotsk, and anadromous S. taranetzi. The Siberian group is close to the Okhotsk one and consists of Taimyr and Baikal region chars as well as Arctic char from Finland. The divergence of char mitochondrial lineages was dated to the Pliocene–Pleistocene.

Relationships and position of the genus Neozoarces of the subfamily neozoarcinae in the system of the suborder Zoarcoidei (Pisces, Perciformes) by molecular-genetic data

Using the method of molecular-genetic analysis, we investigated the genus Neozoarces (subfamily Neozoarcinae) to reveal its relationships and position in the system of the suborder Zoacoidei. Comparison with representatives of other families of this suborder demonstrated that the lowest level of differences is observed between Neozoarces and subfamilies of the family Zoarcidae (the mean value of genetic divergence is 11.9%) with which it forms a general cluster on the phylogenetic tree. From representatives of the family Stichaeidae, Neozoarces differs at the same level (13.9%) as from the families Bathymasteridae, Pholidae, Ptilichthyidae, and Zaproridae (14.0%). The results of investigations confirm the viewpoint suggested by Makushok (1961) who included, for the first time, the subfamily Neozoarcinae to the family Zoarcidae on the basis of comparative morphological investigation of these groups.

Relationships and position of wrymouths of the family cryptacanthodidae in the system of the suborder Zoarcoidei (Pisces, Perciformes)

To determine the taxonomic position of wrymouths of the family Cryptacanthodidae in the system of the suborder Zoarcoidei, a study on molecular genetics and comparative morphology of Cryptacanthodes bergi from Peter the Great Bay (Sea of Japan) is conducted. Based on molecular genetic analysis using the genes of nuclear and mitochondrial DNA, Cryptacanthodes bergi is substantially similar to the representatives of the superfamily Stichaeoidae. Thus, the opinion of Makushok on a phylogenetically distinct position of wrymouths in relation to snake blennies and related families is not supported. The anatomical features of skull structure support the data of molecular genetics. The directions and time of distribution of wrymouths in the northwest Atlantic through the channel in the area of the Isthmus of Panama in approximately the late Miocene are discussed.

Relationships and position of the taxa of the subfamily Xiphisterinae in the system of the suborder Zoarcoidei (Perciformes)

Analysis of the nucleotide sequences of mitochondrial and nuclear DNA genes was used to examine the relationships and position of the subfamily Xiphisterinae in the system of the suborder Zoarcoidei. This study showed the genetic heterogeneity of Xiphisterinae and the propriety of its division into two subfamilies: Xiphisterinae with the genera Xiphister and Phytichthys and Cebidichthyinae with the genera Cebidichthys, Dictyosoma, Esselenichthys, and Nivchia. The genetic differences between the two subfamilies were not less, but in some cases even greater than the differences between families within the suborder; therefore, they should be raised to the rank of a family, Xiphisteridae and Cebidichthyidae, and classified not within the superfamily Stichaeoidae but rather as independent taxa of the suborder Zoarcoidei.

Position of neck banded blenny Leptostichaeus pumilus (Perciformes: Zoarcoidei) in the system of the suborder Zoarcoidei as inferred from molecular genetic data

Molecular genetic study of genetic variations within COI, cytochrome b, and 16S rRNA of mitochondrial DNA in neck banded blenny Leptostichaeus pumilus, which was earlier assigned to the family Stichaeidae, indicates that the species is most close to a group combining the families Zoarcidae, Neozoarcidae, and Anarhichadidae. Significant genetic differences between neck banded blenny and the family Stichaeidae correspond to the level of divergence between other families of the suborder Zoarcoidei (Zaproridae, Ptilichthyidae, Pholidae, Cryptacanthodidae, and Bathymasteridae).

Phylogenetic relations in the family pholidae (Perciformes: Zoarcoidei) based on genetic and morphological data

Molecular-genetic study of Pholidae of the suborder Zoarcoidei was first performed. Analysis of variation of genes of COI, cytochrome b, and 16S rRNA of mitochondrial DNA indicates different phylogenetic isolation of the family taxa. The groundlessness of separating subgenera (or genera) Enedrias and Allopholis and the rightfulness of including them in the composition of the genus Pholis are shown. Genetic close relation of the genera Pholis and Rhodymenichthys and their differences from the genus Apodichthys are established. The obtained results agree with the data of Makushok (1958) who separated in the composition of the family two subfamilies—Pholinae (with genera Pholis and Rhodymenichthys) and Apodichthyinae (with the genera Apodichthys, Xererpes, and Ulvicola). A key to species, genera, and subfamilies of gunnels of the northern part of the Pacific Ocean is provided.

Restriction Fragment Variation of the Mitochondrial Gene of Cytochrome b in Some Taxa of the Eelpout Family (Pisces, Perciformes, Zoarcidae) from the Northern Sea of Okhotsk

The first analysis of restriction fragment length polymorphism (RFLP) of the mitochondrial gene of cytochrome b of fish from the Eelpout Family (Zoarcidae) from the northern Sea of Okhotsk has been performed. The mean genetic distances between the subfamilies Zoarcinae and Lycodinae, subfamilies Lycodinae and Gymnelinae, and subfamilies Zoarcinae and Gymnelinae are 11.14, 13.87, and 14.00%, respectively. Species of the genus Lycodes (Lycodinae) are characterized by a mtDNA small divergence (on average, 2.04%) and are divided into two groups on the basis of lateral line morphology. Magadania skopetsi, an endemic of Tauiskaya Bay of the Sea of Okhotsk, is genetically close to Hadropareia middendorffii from the same subfamily (Gymnelinae). The mtDNA sequences of species from the genus Lycogrammoides (Lycodinae) differ by 3.83%. The genetic differences between the eelpout Zoarces elongatus Zoarces sp. (d = 4.54%) suggest that the latter is a separate species.