Cryptic taxonomic diversity and high-latitude melanism in the glossiphoniid leech assemblage from the Eurasian Arctic.

The family Glossiphoniidae is a diverse and widespread clade of freshwater leeches, playing a significant role in functioning of aquatic ecosystems. The taxonomy and biogeography of leeches from temperate, subtropical, and tropical regions attracted much attention of zoologists, while their taxonomic richness and distribution in the Arctic are poorly understood. Here, we present an overview of the Eurasian Arctic Glossiphoniidae based on the most comprehensive occurrence and DNA sequence datasets sampled to date.

No strict host specificity: Brain metacercariae Diplostomum petromyzifluviatilis Müller (Diesing, 1850) are conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014).

Metacercariae of Diplostomum petromyzifluviatilis (Digenea, Diplostomidae) from the brain of European river lamprey Lampetra fluviatilis from the Baltic Sea basin and Arctic lamprey Lethenteron camtschaticum from the White Sea basin were studied with the use of genetic and morphological methods. Phylogenetic analysis based on cox1 marker showed that the parasites of both lamprey species were conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al.

Fatty Acid Composition and Contents of Fish of Genus from Natural Ecosystems and Aquaculture.

Fatty acids (FA) of muscle tissue of species and its forms, , , , and , from six Russian lakes and two aquacultures, were analyzed. Considerable variations in FA compositions and contents were found, including contents of eicosapentaenoic and docosahexaenoic acids (EPA and DHA), which are important indicators of fish nutritive value for humans. As found, contents of EPA+DHA (mg·g wet weight) in muscle tissue of species and forms varied more than tenfold.

The Center of Origin and Colonization Routes of Noble Salmons of the Genus Salmo (Salmonidae, Actinopterigii).

Genetic diversity and colonization routes of noble salmons were studied using a partial nucleotide sequence of the mitochondrial COI gene. The brown trout S. trutta, which is the most ancient species of the genus, was concluded to originate from the modern southeastern Pontic-Caspian area, which is currently inhabited by members of the subspecies S.

Polyunsaturated Fatty Acid Content in Muscle Tissue Is Associated with the Duration of Embryo Development in Salmonoid Fishes (Salmonoidei).

A hypothesis was advanced and grounded that the total content of eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic (DHA, 22:6n-3) acids in fish muscle tissue is associated with the species-specific (taxon-specific) duration of embryo development. A meta-analysis of the original and published data was performed using fishes of the families Coregonidae and Salmonidae as an example. Fishes with longer embryo development times, which are observed at lower temperatures, were found to have significantly higher EPA + DHA contents in muscles as compared with the species that belong to the same families but have shorter embryo development times.

Integrative taxonomy, biogeography and conservation of freshwater mussels (Unionidae) in Russia.

Freshwater mussels are ecosystem engineers and keystone species in aquatic environments. Unfortunately, due to dramatic declines this fauna is among the most threatened globally. Here, we clarify the taxonomy and biogeography of Russian Unionidae species based on the most comprehensive multi-locus dataset sampled to date.

Freshwater mussels house a diverse mussel-associated leech assemblage.

Freshwater mussels (Unionida) are one of the most imperiled animal groups worldwide, revealing the fastest rates of extinction. Habitat degradation, river pollution and climate change are the primary causes of global decline. However, biological threats for freshwater mussels are still poorly known.

Resident and Anadromous Forms of Arctic Charr (Salvelinus alpinus) from North-East Europe: An Example of High Ecological Variability without Speciation.

Samples from 11 populations of the Arctic char of the North-European part of Russia belonging to the anadromous and resident forms and two samples from Lake Sobach'e (Taimyr) were studied. The nucleotide sequence of the mitochondrial COI gene was determined in 60 individuals. In the majority of populations, the same COI haplotype was found.

Fish hosts, glochidia features and life cycle of the endemic freshwater pearl mussel Margaritifera dahurica from the Amur Basin.

Margaritiferidae is a small freshwater bivalve family with 16 species. In spite of a small number of taxa and long-term history of research, several gaps in our knowledge on the freshwater pearl mussels still exist. Here we present the discovery of host fishes for Margaritifera dahurica, i.

Sex Determination Model in Pink Salmon Oncorhynchus gorbuscha (Walbaum, 1792) (Salmonidae, Osteichthyes) Controlled by Multi-Copy Genes Located in Sex Chromosomes.

This article is devoted to presenting the hypothesis explaining the fact of a considerable prevalence of phenotypic males among the triploid pink salmon as well as the regular occurrence of intersexes, which were revealed by us. This hypothesis also explains the large proportion (in some cases) in pink salmon populations of the individuals whose genetic sex does not match the phenotypic sex. We assume that the genes encoding the factors that contribute to the transformation of individuals into males (but not the marker sequences of the Y chromosome) are present not only in the Y chromosome of pink salmon but also in the X chromosome, although in smaller quantities.

Climate Warming as a Possible Trigger of Keystone Mussel Population Decline in Oligotrophic Rivers at the Continental Scale.

The effects of climate change on oligotrophic rivers and their communities are almost unknown, albeit these ecosystems are the primary habitat of the critically endangered freshwater pearl mussel and its host fishes, salmonids. The distribution and abundance of pearl mussels have drastically decreased throughout Europe over the last century, particularly within the southern part of the range, but causes of this wide-scale extinction process are unclear. Here we estimate the effects of climate change on pearl mussels based on historical and recent samples from 50 rivers and 6 countries across Europe.

A Narrowing of the Phenotypic Diversity Range after Large Rearrangements of the Karyotype in Salmonidae: The Relationship between Saltational Genome Rearrangements and Gradual Adaptive Evolution.

The problem of how a gradual development of ecological and morphological adaptations combines with large genome rearrangements, which have been found to occur in the phylogeny of many groups of organisms, is a matter of discussion in the literature. The objective of this work was to study the problem with the example of salmonids, whose evolution included at least six events of multiple chromosome fusions. Large karyotype rearrangements are associated with a decrease in ecological and morphological diversity in salmonids.

Fatty Acid Composition and Contents of Seven Commercial Fish Species of Genus Coregonus from Russian Subarctic Water Bodies.

In several Russian northern lakes and rivers, Arctic cisco Coregonus autumnalis, least cisco C. sardinella, peled C. peled, tugun C.

Triploidy does not decrease contents of eicosapentaenoic and docosahexaenoic acids in filets of pink salmon Oncorhynchus gorbuscha.

Triploid fish has become an important item of commercial aquaculture, but data on its fatty acid (FA) composition are still controversial, especially regarding essential polyunsaturated fatty acids, eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA). We studied FA composition and content of diploid and triploid pink salmon Oncorhynchus gorbuscha, reared in aquaculture in a bay of the White Sea (Russia). FA composition, measured as percentages of total FA of triploids and immature diploid females significantly differed from that of mature diploid fish.

[Abnormal development of gonads of dwarf females and low survival of their offspring as the cause of rarity of resident populations of Atlantic salmon (Salmo salar L.)].

Fecundity and mass of eggs, as well as survival of offspring, of hatchery-reared small (less than 406 g) females of Atlantic salmon are determined. The absolute fecundity and mass of egg of artificially reared fish are sufficiently less than that of anadromous spawners. Small females are characterized by delayed spawning; histological analysis has demonstrated significant asynchrony in oocyte development of some specimens.

[Results of testing the comparative method: the curvature of the shell valve frontal section is inappropriate as a systematic character for the freshwater pearl mussel of the genus Margaritifera].

This paper continues a discussion on the number of pearl mussel species of the genus Margaritifera in northern Europe. A biometric study of 1711 pearl mussel Margaritifera margaritifera shells from 15 rivers in Russia and Latvia (basins of the White and Baltic seas) has been conducted. All the examined samples fall into two groups: the northern group (with the shells more flattened on average, f.

[Variation in the timing of spawning of the Black Sea brown trout Salmo trutta labrax Pallas under artificial and natural conditions].

Analysis of the maturation and spawning times of the Black Sea brown trout bred at the fish-farming plants and inhabiting natural waterways of the Northwestern Caucasus has demonstrated a considerable variation depending on environmental conditions, first and foremost, temperature. This fact, as well as the analysis of literature data, suggests that the duration and timing of the spawning season cannot be used as self-sufficient criteria for identifying species of the genus Salmo.

[Does freshwater pearl mussel (Margaritifera margaritifera) change life-history of Atlantic salmon (Salmo salar)?].

The critical analysis of the literature data shows that infection of freshwater pearl mussel glochidia does not influence the duration of freshwater period of the Atlantic salmon's life, as well as on all life cycle duration of this fish. Such infection does not influence health of Atlantic salmon or worsens slightly. There are no experimental data about symbiosis between pearl mussel and salmonid fishes.

[Hybridization of two mussel species Dreissena polymorpha (Pallas, 1771) and Dreissena bugensis (Andrusov, 1897) in natural environment].

Dreissenids display a high diversity of shell morphology, and it is frequently difficult to ascribe some individuals from mixed populations to one of the two species, Dreissena polymorpha (Pallas, 1771) or D. bugensis (Andrusov, 1897). Presumably, such individuals may be interspecific hybrids.

[Detection of the mitochondrial DNA haplotype characteristic of the least cisco (Coregonus sardinella, Valenciennes, 1848) in the vendace (C. albula, Linnaeus, 1758) population of Vodlozero (the Baltic Sea basin)].

Analysis of the nucleotide sequence of the mitochondrial ND-1 gene in the vendace population in lake Vodlozero (the eastern part of the Baltic Sea basin) revealed a sequence variant that is closely related to that of the least cisco of Siberia (the Indigirka River). Thus, together with the results of morphological and allozyme analysis of this population performed earlier, the results obtained in this study are suggestive of the immigration of the least cisco to the Baltic Sea basin during the last glaciation.

[Freshwater Pearl mussels of the genus Margaritifera (Mollusca: Bivalvia) described as M. elongata (Lamarck, 1819) and M. borealis (Westerlund, 1871) should be classified with M. margaritifera (Linnaeus, 1758)].

The shells of Pearl mussels from the basins of the Solza, Keret', and Umba rivers flowing into the White Sea have been measured to determine the ratio of shell convexity to its maximum height. This ratio is the main character that, according to Bogatov et al. (2003), allows one to distinguish between three species of the genus Margaritifera: M.

[Dispersal routes and species identification of freshwater animals in Northern Europe: a review of molecular evidence].

According to genetic data, North European freshwater areas were colonized from refugia along the eastern Atlantic coast, in southern and eastern areas of Baltic Sea, in Siberia, North America, and areas of the Caspian and Black seas. Probably, a refugium also existed in Southern Norway. Colonization from the sea also took place.

[Uncontrolled genetic processes in artificial populations: proving the leading role of selection in evolution].

The review considers studies examining artificially maintained populations as models for understanding biological evolution. The key factors of gene pool evolution-random processes, interspecific hybridization, migration, mutation, and selection--are analyzed. We present evidence indicating that selection is the leading evolutionary factor that regulates the operation of other factors, directly or through genetic systems.

[Hybridization between Atlantic salmon Salmo salar L. and brown trout S. trutta l. upon artificial propagation].

Samples of Salmo salar and S. trutta were examined in 12 Russian fish hatcheries. With protein markers, hybrids of the two species were found in three hatcheries of the Baltic Sea basin.