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Anoxia is a significant challenge for most animals, as it can lead to tissue damage and death. Among amphibians, the Siberian frog Rana amurensis is the only known species capable of surviving near-zero levels of oxygen in water for a prolonged period. In this study, we aimed to compare metabolomic profiles of the liver, brain, and heart of the Siberian frog exposed to long-term oxygen deprivation (approximately 0.2 mg/L water) with those of the susceptible Far Eastern frog (Rana dybowskii) subjected to short-term hypoxia to the limits of its tolerance. One of the most pronounced features was that the organs of the Far Eastern frog contained more lactate than those of the Siberian frog despite a much shorter exposure time. The amounts of succinate were similar between the two species. Interestingly, glycerol and 2,3-butanediol were found to be significantly accumulated under hypoxia in the Siberian frog, but not in the Far Eastern frog. The role and biosynthesis of these substances are still unclear, but they are most likely formed in certain side pathways of glycolysis. Based on the obtained data, we suggest a pathway for metabolic changes in the Siberian frog under anoxia.

The aim of our study is to assess changes in soil macroinvertebrate biodiversity when conventional tillage (CT) is replaced by no-tillage (NT) in agroecosystems of the southern part of the West Siberian forest steppe. The research was conducted in the Novosibirsk region at the end of May 2017, May 2018, and in June 2018. The agricultural plots with CT and NT were located close to each other on identical soils, at a distance of about 200 m from the nearest forest shelterbelts. NT technology has been applied on the experimental plot since 2007. Sampling of invertebrates was conducted in two ways, namely soil sampling and pitfall trapping. The majority of basic physicochemical properties of soil were the same or similar between the CT and NT plots. However, depending on the type of tillage, different soil invertebrate communities had already developed in the control (CT) and experimental (NT) plots during this time. The community of the CT plot includes a large number of flying predatory Carabidae species typical of early successional stages (such as Bembidion properans and B. quadrimaculatum, Poecilus spp.) and phytophages, i.e., larvae of Elateridae. The NT plot has significantly higher density and species richness of earthworms (Eisenia nordenskioldi and synanthropic E. fetida in the NT plot versus one individual of E. nordenskioldi in the CT plot). The NT plot has a significantly richer and more abundant assemblage of spiders (especially in spring) and a poor assemblage of insect predators (except for the superdominant ground beetle Poecilus cupreus and the subdominant P. versicolor in summer 2018). Large numbers of larvae of some carabids (e.g., Amara consularis) were found in the NT soil, suggesting that they complete a full life cycle in this habitat.

Earthworm invasions often reduce biodiversity and affect the ability of ecosystems to perform ecosystem functions. Over the past few decades, European lumbricid species have spread widely in natural habitats in Western Siberia, without completely displacing the native species. The aim of the present experiment is to study the survival, reproductive potential, vertical distribution, abundance, and biomass of Aporrectodea caliginosa and Lumbricus rubellus invasive species for the region and the native species Eisenia nordenskioldi and their influence on each other. For this purpose, winter and vegetation experiments were conducted in mesocosms simulating the real situation of invasions in the same communities on the same types of soils with the same amount and composition of litter. The authors found that the native species was significantly inferior to A. caliginosa in reproduction rate, number of offspring, and final biomass, but had an advantage over L. rubellus. The native species was positively influenced by the presence of A. caliginosa. In the experiment, there was a significant rejuvenation of the populations of the studied species, as well as an increase in abundance and relative mass under interaction conditions compared to mono variants. The native species had advantages over the invasive species in terms of winter survival. The natural volume of litter used in the experiment was insufficient for L. rubellus. According to the results of the experiment, it can be assumed that the spread of L. rubellus will continue to be limited to non-freezing biotopes rich in organic matter. A. caliginosa will spread in natural communities and agrocenoses of Western Siberia.

The geographic variability of the cold hardiness of poikilothermic animals is one of the keys to understanding the mechanisms of the formation of their ranges under climate change or anthropogenic introductions. A convenient object is the small tortoiseshell butterfly Aglais urticae, which is distributed from the Atlantic Ocean to the Pacific Ocean. On the edges of the distribution range, the difference between the averages of the absolute minimum air temperatures reaches 60 °C. The cold hardiness (supercooling point and lower lethal temperatures) of imago wintering in a supercooled state in the northeast of Russia was assessed in comparison to the previously studied European ones. Despite the huge difference in air temperatures, the mean supercooling points ranges in the east (−23...−29 °C) and the west (−17...−22 °C) differ by only 7 °C; the lower lethal temperatures for this species is near −30 °C. The identified cold hardiness is not enough for overwintering of A. urticae on the vast majority part of the species range in natural shelters above the level of snow cover. The inhabiting of A. urticae in regions with air temperatures below −30 °C is possible only when wintering under snow. This primitive behavioral adaptation probably does not require physiological changes and may not be unique to Lepidoptera.

Abstract Background Many earthworm species demonstrate significant cryptic diversity, with several highly diverged mitochondrial lineages found within most of the taxa studied to date. The status of differences between these lineages on the nuclear level is still unclear. Because of widespread polyploidy in earthworms, most studies were limited to two nuclear loci, the ribosomal and the histone clusters. Here we attempted to elucidate the status of a set of genetic lineages within Eisenia nordenskioldi nordenskioldi, an earthworm species from Northern Asia with high intraspecific diversity. We performed RNA-seq on an IonTorrent platform for five specimens of this species belonging to five genetic lineages, as well as two outgroups from the family Lumbricidae, the congenetic E. andrei, and Lumbricus rubellus. Results We de novo assembled transcriptomes and constructed datasets of genes present in all seven specimens using broad (ProteinOrtho; 809 genes) and narrow (HaMStR; 203 genes) ortholog assignment. The majority of orthologs had identical amino acid sequences in all studied specimens, which we believe was due to strong bias towards the most conserved genes. However, for the rest of genes the differences among the lineages were lower than those between them and the congeneric E. andrei. Both datasets yielded phylogenetic trees with the same topology. E. n. nordenskioldi was found to be monophyletic. The differences on the genetic level had no concordance with geography, implying complex history of dispersal. Conclusions We found that genetic lineages of E. n. nordenskioldi are genetically distinct on nuclear level and probably diverged long ago. Current data implies that they might even represent distinct species within the E. nordenskioldi species complex.

Ants of the «Formica picea—F. candida» complex are widespread across Eurasia. However, it is still a matter of debate if it constitutes one or two species. In this study, we collected a sample of specimens from different parts of Eurasia, sequenced the mitochondrial cox1 and cytb genes, as well as three nuclear loci—wg, Top1, and ITS2—and analyzed the available published data. We found this complex to contain a new, yet undescribed, taxon that has a large distribution in Siberia and East Asia. Thus, the «Formica picea—F. candida» complex consists of at least three taxa with distinct distributions.

The moor frog Rana arvalis is one of a few amphibians that can tolerate freezing to low temperatures, up to −16 °C. In this study, we performed metabolomic analysis of the liver and hindlimb muscles of frozen and control R. arvalis. We found that the moor frog synthesizes glucose and glycerol in similar concentrations as low molecular weight cryoprotectants. This is the first such case reported for the genus Rana, which was believed to use glucose only. We found that freezing upregulates glycolysis, with the accumulation of several end products: lactate, alanine, ethanol, and, possibly, 2,3-butanediol. To our knowledge, this is also the first report of ethanol as an end product of glycolysis in terrestrial vertebrates. We observed highly increased concentrations of nucleotide degradation products, implying high level of stress. The Krebs cycle arrest resulted in high concentrations of succinate, which is common for animals. However, we found almost no signs of adaptations to reoxygenation stress, with overall low levels of antioxidants. We also performed metabolomics analysis of subcutaneous ice that was found to contain glucose, glycerol, and several other substances.

Eisenia nordenskioldi (Eisen, 1879) is the only autochthonous Siberian earthworm with a large distribution that ranges from tundra to steppe and broadleaved forests. This species has a very high morphological, ecological, karyological, and genetic diversity, so it was proposed that E. nordenskioldi should be split into several species. However, the phylogeny of the complex was unclear due to the low resolution of the methods used and the high diversity that should have been taken into account. We investigated this question by (1) studying the diversity of the COI gene of E. nordenskioldi throughout its range and (2) sequencing transcriptomes of different genetic lineages to infer its phylogeny. We found that E. nordenskioldi is monophyletic and is split into two clades. The first one includes the pigmented genetic lineages widespread in the northern and western parts of the distribution, and the second one originating from the southern and southeastern part of the species' range and representing both pigmented and non-pigmented forms. We propose to split the E. nordenskioldi complex into two species, E. nordenskioldi and Eisenia sp. 1 (aff. E. nordenskioldi), corresponding to these two clades. The currently recognized non-pigmented subspecies E. n. pallida will be abolished as a polyphyletic and thus a non-natural taxon, while Eisenia sp. 1 will be expanded to include several lineages earlier recognized as E. n. nordenskioldi and E. n. pallida.

Tilia sibirica and T. nasczokinii are considered to be endemic Siberian linden species. They have very small distributions located hundreds to thousands of kilometers away from other lindens. It is unclear how closely these species are related to the widespread Tilia cordata: according to the current hypotheses, they could be pre-Pleistocene relicts or remnants of the recent continuous range of T. cordata that existed during the Holocene climatic optimum. Earlier studies detected significant differences between T. sibirica, T. nasczokinii, and T. cordata in microsatellite loci, but not in plastid sequences. Here we performed a phylogenetic analysis of several linden species based on GBS data. The obtained GBS sequences were assembled to create phylogenetic trees based on 16,000–294,000 variable sites. We found that T. cordata and the two putative Siberian species formed a monophyletic group. It consisted of three clades: the basal clade containing specimens from the Caucasus, and two sister clades representing populations from the East European Plains+the Urals and Siberia, respectively. Neither of the Siberian species was related to the Far Eastern T. amurensis, as was hypothesized earlier. Our study suggests that the colonization of Europe and Siberia after the Last Glacial Maximum occurred from different glacial refugia.

The Siberian salamander Salamandrella keyserlingii Dybowski, 1870 is a unique amphibian that is capable to survive long-term freezing at −55 °C. Nothing is known on the biochemical basis of this remarkable freezing tolerance, except for the fact that it uses glycerol as a low molecular weight cryoprotectant. We used 1H-NMR analysis to study quantitative changes of multiple metabolites in liver and hindlimb muscle of S. keyserlingii in response to freezing. For the majority of molecules we observed significant changes in concentrations. Glycerol content in frozen organs was as high as 2% w/w, which confirms its role as a cryoprotectant. No other putative cryoprotectants were detected. Freezing resulted in ischemia manifested as increased concentrations of glycolysis products: lactate and alanine. Unexpectedly, we detected no increase in concentrations of succinate, which accumulates under ischemia in various tetrapods. Freezing proved to be a dramatic stress with reduced adenosine phosphate pool and high levels of nucleotide degradation products (hypoxanthine, β-alanine, and β-aminoisobutyrate). There was also significant increase in the concentrations of choline and glycerophosphocholine, which may be interpreted as the degradation of biomembranes. Thus, we found that freezing results not only in macroscopical damage due to ice formation, but also to degradation of DNA and biomembranes.

The Kuril Archipelago is a part of the Circum-Pacific Belt (Ring of Fire). These islands have numerous thermal springs. There are very few studies on these microbial communities, and none of them have been conducted by modern molecular biological methods. Here we performed the first metagenomic study on two thermophilic microbial communities of Kunashir Island. Faust Lake is hot (48 °C) and highly acidic (pH 2.0). We constructed 28 metagenome-assembled genomes as well as 17 16S ribosomal RNA sequences. We found that bottom sediments of Faust Lake are dominated by a single species of red algae belonging to the Cyanidiaceae family. Archaeans in Faust Lake are more diverse than bacteria but less abundant. The Tretyakovsky Thermal Spring is also hot (52 °C) but only weakly acidic (pH 6.0). It has much higher microbial diversity (233 metagenome-assembled genomes; 93 16S ribosomal RNAs) and is dominated by bacteria, with only several archaeans and one fungus. Despite their geographic proximity, these two thermal springs were found to not share any species. A comparison of these two lakes with other thermal springs of the Circum-Pacific Belt revealed that only a few members of the communities are shared among different locations.

Aporrectodea rosea is a cosmopolitan earthworm species widespread in agricultural soils throughout the world. In this paper, we present its complete mitochondrial genome, which is a circular molecule 15,086 bp long and has gene content and arrangement typical for earthworm mtDNA.

Opisthorchis felineus or Siberian liver fluke is a trematode parasite (Opisthorchiidae) that infects the hepato-biliary system of humans and other mammals. Despite its public health significance, this wide-spread Eurasian species is one of the most poorly studied human liver flukes and nothing is known about its population genetic structure and demographic history. In this paper, we attempt to fill this gap for the first time and to explore the genetic diversity in O. felineus populations from Eastern Europe (Ukraine, European part of Russia), Northern Asia (Siberia) and Central Asia (Northern Kazakhstan). Analysis of marker DNA fragments from O. felineus mitochondrial cytochrome c oxidase subunit 1 and 3 (cox1, cox3) and nuclear rDNA internal transcribed spacer 1 (ITS1) sequences revealed that genetic diversity is very low across the large geographic range of this species. Microevolutionary processes in populations of trematodes may well be influenced by their peculiar biology. Nevertheless, we suggest that lack of population genetics structure observed in O. felineus can be primarily explained by the Pleistocene glacial events and subsequent sudden population growth from a very limited group of founders. Rapid range expansion of O. felineus through Asian and European territories after severe bottleneck points to a high dispersal potential of this trematode species.