Geographic and genetic boundaries of brown bear (Ursus arctos) population in the Caucasus

The taxonomic status of brown bears in the Caucasus remains unclear. Several morphs or subspecies have been identified from the morphological (craniological) data, but the status of each of these subspecies has never been verified by molecular genetic methods. We analysed mitochondrial DNA sequences (control region) to reveal phylogenetic relationships and infer divergence time between brown bear subpopulations in the Caucasus. We estimated migration and gene flow from both mitochondrial DNA and microsatellite allele frequencies, and identified possible barriers to gene flow among the subpopulations. Our suggestion is that all Caucasian bears belong to the nominal subspecies of Ursus arctos. Our results revealed two genetically and geographically distinct maternal haplogroups: one from the Lesser Caucasus and the other one from the Greater Caucasus. The genetic divergence between these haplogroups dates as far back as the beginning of human colonization of the Caucasus. Our analysis of the least‐cost distances between the subpopulations suggests humans as a major barrier to gene flow. The low genetic differentiation inferred from microsatellite allele frequencies indicates that gene flow between the two populations in the Caucasus is maintained through the movements of male brown bears. The Likhi Ridge that connects the Greater and Lesser Caucasus mountains is the most likely corridor for this migration.     

Variability of the upper incisors in the cave bears (Carnivora,Ursidae) from the Caucasus and Urals

Morphometric and morphotypic variability of the cave bear upper incisors from two different geographic regions (Caucasus and Urals), different stratigraphic periods (middle and late Pleistocene), and bearing different mitochondrial haplogroups (kudarensis and ingressus) was studied. The specific diet of the cave bears, i.e. hard vegetables, led to noticeable differences between their incisors and the incisors of the brown bear (Ursus arctos). It was found that the upper incisors of the Caucasian cave bears from different stratigraphic periods demonstrate consistent development of their morphology. The late Pleistocene cave bears from the Urals show a greater similarity to the Caucasian cave bears from earlier periods than with the cave bears from later periods. Our results suggest that the incisor morphology has evolved independently in the Caucasian and Ural cave bears as they belong to different phylogenetic lineages and display different ways of adaptation to local environmental conditions.     

Les hommes de Néandertal du Caucase du Nord : entre l’Ouest et l’Est

A geographical position of the Caucasus in the border between Europe and Asia defines a complex character of the Middle Paleolithic in the region as a whole and in the Northern Caucasus in particular. Today, we can recognize three major cultural areas existed during the Middle Paleolithic in the Northern Caucasus: (1) a local North Caucasian variant of Eastern Micoquian, which is closely related to Eastern Micoquian of Central and Eastern Europe, in the Northwestern Caucasus; (2) a specific Caucasian industry type (called Khostinian Mousterian), which penetrated during later MIS 3 to the Northwestern Caucasus from the Northeastern Black sea cost in the Southern Caucasus; and (3) a similar to Zagros Mousterian industry, which is presented in Weasel Cave in the Northeastern Caucasus.     

Karyotype structure and polymorphism peculiarities of Chironomus nuditarsis Keyl, 1961 (Diptera,Chironomidae) from natural populations of North Caucasus

The study presents data on the karyotype characteristics and features of chromosomal polymorphism of Chironomus nuditarsis Keyl, 1961 (Diptera, Chironomidae) from seven natural populations of Caucasus (Northwest, Central and East Caucasus). We found 16 banding sequences in the Caucasian populations. We observed inversion polymorphism almost in all chromosome arms except for arms C and E. The genetic distances between all the studied populations of Ch. nuditarsis were calculated using Nei criteria (1972). In spite of relative geographic proximity, the genetic distances between populations of the Caucasus are quite big, and they do not form a single cluster of Caucasian populations. The population of the Northwest Caucasus goes to European cluster; the populations of Central and East Caucasus form their own separate clusters. The principal component analysis (PCA) shows the similar picture. We suggest that such a clear separation of Caucasian populations in distinct clusters is a result of differences of collection sites in terms of geography and climate (complex diverse terrain and microclimate conditions). Four of the Caucasian populations do not follow Hardy-Weinberg expectation. In two populations, there being a marked deficiency of heterozygotes in arms B, F and G. In two other populations, there being a marked excess of heterozygotes in arms B and G. One can suggest that observed pictures could be a reflection of multi-directional selection of heterozygotes in different populations. The populations of Ch. nuditarsis from different parts of the Caucasus possibly diverged from each other at the level of subspecies. All the obtained data are indicative of the complex genetic structure of Caucasian populations of Ch. nuditarsis and total complexity of microevolution processes occurring in the Caucasus region.     

Towards resolving the evolutionary history of Caucasian pears (Pyrus,Rosaceae)—Phylogenetic relationships,divergence times and leaf trait evolution

With approximately 25 endemic species, the genus Pyrus (pears) is highly diverse in the Caucasus ecoregion. The majority of Caucasian pears inhabit xerophytic open woodlands or similar habitats, to which they display morphological adaptations, such as narrow leaves. The other species, both Caucasian and non‐Caucasian taxa, mainly inhabit mesophytic forests and display broad leaves. Using a representative taxon sampling of Pyrus from the Caucasus, Europe and Asia, we reconstruct phylogenetic relationships in the genus based on multiple plastid regions. We also estimate the divergence times of major clades in Pyrus, reconstruct the evolution of leaf shapes, and discuss the emergence of xeromorphic leaf traits. Our results confirm the monophyly of Pyrus and the existence of two major clades: (a) an E Asian clade with a crown group age of 15.7 (24.02–8.37 95% HPD) My, and (b) a W Eurasian clade that comprises species from Europe, SW Asia and the Caucasus and that displays a slightly younger crown group of 12.38 (19.02–6.41 95% HPD) My. The existing infrageneric classification of Pyrus was found partially incongruent with the inferred phylogenetic trees. Several currently accepted species were not recovered as monophyletic, indicating that current species limits require re‐evaluation. Ancestral character state reconstructions revealed several independent transitions from broad‐ to narrow‐shaped leaves in Pyrus, probably via intermediate‐shaped leaves.     

Genetic differentiation of <Emphasis Type="Italic">Puccinia triticina</Emphasis> Erikss. in Russia

A collection of Puccinia triticina isolates was characterized for polymorphism of microsatellite loci and estimated for their differentiation by geographic origin. The collection included 20 isolates from the Ural region, 31 from West Siberia, 53 from Central Europe, 32 from the Northwest region, 32 from the Volga region, and 40 from the North Caucasus (24 from Dagestan and 16 from Krasnodar and Stavropol). The studied isolates were represented by 65 virulence phenotypes. In the polymorphism analysis of 18 microsatellite loci, 69 genotypes were determined. The index values of genetic distances (F _st, R _st, KB _c) between populations for microsatellite loci indicated differentiation of P. triticina isolates according to geographical origin, and they were clustered into three groups: (1) Asian, (2) European, and (3) North Caucasian. The North Caucasian isolates from Krasnodar and Stavropol regions were closer in similarity to European isolates than the Dagestan ones. Current analysis confirmed the assumption made earlier on the basis of the virulence analysis about the existence of several geographic fungi populations in Russia.     

First DNA sequences from Asian cave bear fossils reveal deep divergences and complex phylogeographic patterns

Until recently, cave bears were believed to have only inhabited Europe. However, recent morphological evidence suggests that cave bears' geographic range extended as far east as Transbaikalia, Eastern Siberia. These Asian cave bears were morphologically distinct from European cave bears. However, how they related to European lineages remains unclear, stressing the need to assess the phylogenetic and phylogeographic relationship between Asian cave bears and their European relatives. In this work, we address this issue using a 227 base-pair fragment of the mitochondrial control region obtained from nine fossil bone samples from eight sites from the Urals, Caucasus, Altai Mountains, Ukraine and Yana River region in Eastern Siberia. Results of the phylogenetic analyses indicate that (i) the cave bear from the Yana River is most closely related to cave bears from the Caucasus region; (ii) the Caucasus/Yana group of bears is genetically very distinct from both European cave bears and brown bears, suggesting that these bears could represent an independent species; and (iii) the Western European cave bear lineage reached at least temporarily to the Altai Mountains, 7000 km east of their known centre of distribution. These results suggest that the diversity of cave bears was greater than previously believed, and that they could survive in a much wider range of ecological conditions than previously assumed. They also agree with recent studies on other extinct and extant species, such as wolves, hyenas and steppe bison, which have also revealed higher genetic and ecological diversity in Pleistocene populations than previously known.     

Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution

Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus) and brown bears (U. arctos) remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus), plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed <1% of the autosomal genome of the ABC Islands brown bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize.     

Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears

Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction.     

Genotype diversity of the Bacillus anthracis strains isolated from the Caucasus region

The study of the genotypes of Bacillus anthracis strains isolated from the Caucasus region was performed using MLVA. Among 149 strains, 32 distinctive MLVA-8 genotypes belonging to Ala, A3a, A4 and B1 molecular diversity groups were identified. 9 genotypes were not described previously; 6 genotypes were not found in other geographic regions and could be considered as endemic for Caucasus. The majority of the identified genotypes are widespread not only in Caucasus, but also throughout Eurasia, Africa, and America. Molecular diversity of Caucasian isolates is comparable to the worldwide diversity. This represents historical relations of this region, proximity to ancient trade routes and intensity of the anthrax epizootic in Caucasus. The obtained results are of interest from the theoretical point of view, as well as for the application in epidemiological research of the anthrax outbreaks.     

A contribution to the knowledge of the longicorn beetles (Coleoptera,Cerambycidae) of the Caucasus: 6. Notes on the distribution of some species with new data of their biology

The distribution of 18 longicorn-beetle species of the Caucasus Isthmus and adjacent regions is discussed. New records of some species are given enlarging their known distribution area in the Caucasus (in some cases, even beyond its limits). The modern knowledge of the distribution of Chlorophorus herbstii, Leptorhabdium caucasicum, and Brachyta caucasica does not confirm occurrence of the first species in the Caucasus and the others, in northern Iran. Stenocorus meridianus occurs only in the northernmost plains of the Ciscaucasia, bordering on Rostov Province. New data on the biology of two little known Caucasian species are given.     

Testing hypotheses of language replacement in the Caucasus: evidence from the Y-chromosome

A previous analysis of mtDNA variation in the Caucasus found that Indo-European-speaking Armenians and Turkic-speaking Azerbaijanians were more closely related genetically to other Caucasus populations (who speak Caucasian languages) than to other Indo-European or Turkic groups, respectively. Armenian and Azerbaijanian therefore represent language replacements, possibly via elite dominance involving primarily male migrants, in which case genetic relationships of Armenians and Azerbaijanians based on the Y-chromosome should more closely reflect their linguistic relationships. We therefore analyzed 11 bi-allelic Y-chromosome markers in 389 males from eight populations, representing all major linguistic groups in the Caucasus. As with the mtDNA study, based on the Y-chromosome Armenians and Azerbaijanians are more closely-related genetically to their geographic neighbors in the Caucasus than to their linguistic neighbors elsewhere. However, whereas the mtDNA results show that Caucasian groups are more closely related genetically to European than to Near Eastern groups, by contrast the Y-chromosome shows a closer genetic relationship with the Near East than with Europe.     

Identifying the risk regions of house break‐ins caused by Tibetan brown bears (Ursus arctos pruinosus) in the Sanjiangyuan region,China

Damage to homesteads by brown bears (Ursus arctos) has become commonplace in Asia, Europe, and the Americas. Science‐based solutions for preventing damages can contribute to the establishment of mechanisms that promote human–bear coexistence. We examined the spatial distribution patterns of house break‐ins by Tibetan brown bears (U. a. pruinosus) in Zhiduo County of the Sanjiangyuan region in China. Occurrence points of bear damage were collected from field surveys completed from 2017 to 2019. The maximum entropy (MaxEnt) model was then used to assess house break‐in risk. Circuit theory modeling was used to simulate risk diffusion paths based on the risk map generated from our MaxEnt model. The results showed that (a) the total risk area of house break‐ins caused by brown bears was 11,577.91 km², accounting for 29.85% of Zhiduo County, with most of the risk areas were distributed in Sanjiangyuan National Park, accounting for 58.31% of the total risk area; (b) regions of alpine meadow located in Sanjiangyuan National Park with a high human population density were associated with higher risk; (c) risk diffusion paths extended southeast to northwest, connecting the inside of Sanjiangyuan National Park to its outside border; and (d) eastern Suojia, southern Zhahe, eastern Duocai, and southern Jiajiboluo had more risk diffusion paths than other areas examined, indicating higher risk for brown bear break‐ins in these areas. Risk diffusion paths will need strong conservation management to facilitate migration and gene flow of brown bears and to alleviate bear damage, and implementation of compensation schemes may be necessary in risk areas to offset financial burdens. Our analytical methods can be applied to conflict reduction efforts and wildlife conservation planning across the Qinghai–Tibet Plateau.     

The recolonization of Europe by brown bears Ursus arctos Linnaeus, 1758 after the Last Glacial Maximum

1. At the end of the Last Glacial Maximum brown bears Ursus arctos recolonized the glacial landscape of Central and Northern Europe faster than all other carnivorous mammal species of the Holocene fauna. Ursus arctos was recorded in Northern Europe from the beginning of the Late-Glacial. The recolonization of northern Central Europe may have taken place directly after the maximum glaciation. The distribution of the brown bear was restricted to glacial refugia only during the Last Glacial Maximum, for probably no more than 10 000 years. 2. Genetic analyses have suggested three glacial refugia for the brown bear: the Iberian Peninsula, the Italian Peninsula and the Balkans. Subfossil records of Ursus arctos from north-western Moldova as well as reconstructed environmental conditions during the Last Glacial Maximum in this area suggest to us a fourth glacial refuge for the brown bear. Because of its connection to the Carpathians, we designate this as the ‘Carpathian refuge’. 3. Due to the low genetic distance between brown bears of northern Norway, Finland, Estonia, north-eastern Russia and the northern Carpathians (the so-called eastern lineage), the Carpathians were considered the geographical origin of the recolonization of these regions. During the recolonization of northern Europe the brown bear probably reached these areas rapidly from the putative Carpathian refuge.     

Genetic Variability of the Grey Wolf Canis lupus in the Caucasus in Comparison with Europe and the Middle East: Distinct or Intermediary Population?

Despite continuous historical distribution of the grey wolf (Canis lupus) throughout Eurasia, the species displays considerable morphological differentiation that resulted in delimitation of a number of subspecies. However, these morphological discontinuities are not always consistent with patterns of genetic differentiation. Here we assess genetic distinctiveness of grey wolves from the Caucasus (a region at the border between Europe and West Asia) that have been classified as a distinct subspecies C. l. cubanensis. We analysed their genetic variability based on mtDNA control region, microsatellite loci and genome-wide SNP genotypes (obtained for a subset of the samples), and found similar or higher levels of genetic diversity at all these types of loci as compared with other Eurasian populations. Although we found no evidence for a recent genetic bottleneck, genome-wide linkage disequilibrium patterns suggest a long-term demographic decline in the Caucasian population – a trend consistent with other Eurasian populations. Caucasian wolves share mtDNA haplotypes with both Eastern European and West Asian wolves, suggesting past or ongoing gene flow. Microsatellite data also suggest gene flow between the Caucasus and Eastern Europe. We found evidence for moderate admixture between the Caucasian wolves and domestic dogs, at a level comparable with other Eurasian populations. Taken together, our results show that Caucasian wolves are not genetically isolated from other Eurasian populations, share with them the same demographic trends, and are affected by similar conservation problems.     

Gene pool of ethnic groups of the caucasus: results of integrated study of the Y chromosome and mitochondrial DNA and genome-wide data

Genetic diversity has been analyzed in 22 ethnic groups of the Caucasus on the basis of data on Y-chromosome and mitochondrial DNA (mtDNA) markers, as well as genome-wide data on autosomal single-nucleotide polymorphisms (SNPs). It has been found that the West Asian component is prevailing in all ethnic groups studied except for Nogays. This Near Eastern ancestral component has proved to be characteristic of Caucasian populations and almost entirely absent in their northern neighbors inhabiting the Eastern European Plain. Turkic-speaking populations, except Nogays, did not exhibit an increased proportion of Eastern Eurasian mtDNA or Y-chromosome haplogroups compared to some Abkhaz-Adyghe populations (Adygs and Kabardians). Genome-wide SNP analysis has also shown substantial differences of Nogays from all other Caucasian populations studied. However, the characteristic difference of Nogays from other populations of the Caucasus seems somewhat ambiguous in terms of the R1a1a-M17(M198) and R1b1b1-M73 haplogroups of the Y chromosome. The state of these haplogroups in Turkic-speaking populations of the Caucasus requires further study.     

Mitochondrial DNA variation in Asian Shepherd Dogs

The hypervariable region of the mitochondrial DNA (mtDNA) control region has been studied in several guardian dog breeds. The genetic diversity is high in the Central Asian Shepherd Dog and the Northern Caucasian Volkodav (an native group of breeds) and low in the Caucasian Shepherd Dog. Haplotypes of groups A, B, C, and E/W have been found in Central Asian Shepherd Dogs; haplotypes of groups A and B, in Caucasian Shepherd Dogs. The data indicates a gene flow from Scandinavian dog populations to the Northern Caucasus. The results of the analysis allow the Caucasian Shepherd Dog, Northern Caucasian Volkodav, Central Asian Shepherd Dog, and the Turkish breeds akbash and kangal to be combined into a single group with an extremely low degree of differentiation.     

Patterns of formation of the flea (Siphonaptera) fauna in the Caucasus

Fleas of the Caucasus belong to 155 species of 40 genera, constituting 17% and 43% of the species and generic composition of the Palaearctic fauna, respectively. The Caucasian fauna includes 23 endemic species but no endemic genera or subgenera. In the number of species, the Caucasian fauna is similar to that of the Mediterranean Subregion and is significantly poorer than the faunas of the Euro-Siberian (by 2.2 times) and Irano-Turanian (by 1.7 times) Subregions. Based on taxonomic diversity, we can propose a hypothesis on the West and East Palaearctic sources of the Caucasian fauna. The West Palaearctic source has determined the distribution of pulicomorph fleas of the families Pulicidae and Coptopsyllidae from Africa, on the one hand, and of fleas of the genera Ctenopthalmus and Palaeopsylla from Europe, on the other hand. Fleas of the Holarctic genera, such as Ceratophyllus and Megabothris, entered the Caucasus by the north Asian route; fleas of the genera Neopsylla, Rhadinopsylla, and Hystrichopsylla migrated to the Caucasus from east and central Asia by the south Asian route, through Middle and Western Asia.