Ural Populations Research Articles

Genetic enrichment of the arctic clonal plantSaxifraga cernuaat its southern periphery via the alpine sexualSaxifraga sibirica

Isolation of populations at the margins of a species range may lead to decreasing genetic diversity via genetic drift and inbreeding. Hybridization between peripheral populations of two species can, however, counteract genetic impoverishment. The mainly clonal, polyploid plant Saxifraga cernua has a wide arctic distribution but also extends southwards into alpine sites. In the Ural Mountains, its peripheral distribution overlaps with that of its sexually reproducing, diploid relative Saxifraga sibirica, and fertile polyploids of more or less intermediate appearance are found in this overlap zone. We used amplified fragment length polymorphism (AFLP) analysis to address the potential impact of interspecific gene flow on genetic diversity in the peripheral populations. A total of 149 plants from 17 populations along a 1650 km south-north gradient were analysed for 253 markers. The results suggest that three Middle Ural populations containing fertile and morphologically more or less intermediate plants have been affected by hybridization. All of these plants formed a strongly supported (100%) group with S. cernua in a neighbour-joining tree, but their AFLP phenotypes assigned either to S. cernua or to artificial (simulated) F(1) hybrids between S. cernua and S. sibirica in multilocus assignment tests. The three populations were highly diverse with virtually every plant representing a distinct AFLP phenotype, providing additional evidence for formation of later-generation hybrids and/or backcrossing to S. cernua. In contrast, other peripheral populations of S. cernua were typically monoclonal, suggesting that hybridization with S. sibirica can increase genetic diversity in S. cernua at its southern periphery.

Factors of maintaining chromosome polymorphism in common vole Microtus arvalis pallas, 1779: Reduced fertility and meiotic drive

The common vole Microtus arvalis (the form obscurus) exhibits polymorphism of a pericentric inversion in chromosome pair 5 throughout the species range. In the Urals populations, the frequency of an acrocentric variant of the heteromorphic chromosome is very low (on average 3.2%) and virtually does not change annually. The factors of maintaining stable chromosomal polymorphism in the common vole were studied under conditions of a laboratory colony. Heterozygous and homozygous for the acrocentric chromosome females showed a significant reduction of the reproductive output irrespective of the male karyotype. This effect was manifested mostly in litter size at birth. A number of cytogenetic and exophenotypic characteristics, as well as parent--offspring transmission of this chromosome in crosses of various types, were examined. We have found meiotic drive in favor of the acrocentric, as a result of which the frequency of the acrocentric (without taking into account the postnatal mortality) totaled over all cross variants (0.48) was significantly higher than that expected with random segregation (0.42). It is likely that meiotic drive of the acrocentric largely compensates for the reduced fertility of its carriers, being among the factors of maintaining it in natural populations.

Mitochondrial DNA Polymorphism in Russian Population form Five Oblasts of the European Part of Russia

New data on mitochondrial DNA polymorphism among Russian population from five oblasts, located within the main ethnic area of Russians, specifically, Ryazan' oblast, Ivanovo oblast, Vologda oblast, Orel oblast, and Tambov oblast (N = 177) are presented. RFLP analysis of the mtDNA coding region showed that most of the mtDNA diversity in the populations examined could be described by main European haplogroups H, U, T, J, K, I, V, W, and X. Haplogroup frequency distribution patterns in the populations of interest were analyzed in comparison with the European and Uralic populations. Based on the haplogroup frequencies, the indices of intraethnic population diversity, Wright's F(st) statistics, and the values of squared deviation from the mean, as well as genetic distances between Russians and European and Uralic populations were estimated. Analysis of these indices along with the anthropological data provided identification of a number of regional groups within the populations examined, which could either result from the interaction of ancient Slavs with different non-Slavic tribes, or could be caused by the ethnic heterogeneity of the ancient Slavs themselves.

Differentiation of the Mitochondrial Subhaplogroup U4 in the Populations of Eastern Europe, Ural, and Western Siberia: Implication to the Genetic History of the Uralic Populations

Phylogenetic relationships between the sequences of the mitochondrial DNA (mtDNA) hypervariable segment 1, belonging to subhaplogroup U4, were examined in the populations of Eastern Europe, Ural, and Northwest Siberia. It was shown that the frequency of subhaplogroup U4, as well as its proportion in the U-component of the gene pools, increased eastwards, reaching maximum values in the populations of Northwest Siberia. Phylogenetic analysis it was showed that the appearance of specific U4-lineage (16113C-16356-16362) in the ancestors of Mansi was most likely caused by its divergence from the East European cluster 16356-16362 in the Late Upper Paleolithic (18566 +/- 12915 years before present). Other U4 mtDNA lineages (16189-16356 and 16311-16356), typical mostly of the indigenous populations of Northwest Siberia (Mansi, Nganasans, and Kets) may have formed during the Neolithic-early Bronze Age (6055 +/- 3599 years before present, on average). It seems likely that the isolation of ancient populations inhabiting the region between the Ob' and Yenisei rivers was the key factor, providing the appearance of the unique Caucasoid mtDNA lineages in their gene pools. These results were consistent with the traditional point of view on the mixed origin of the Finno-Ugric populations of the Volga-Ural region and West Siberia, resulted from the genetic relationships between the populations of Europe and Asia.

Genetic Structure of the Volga–Ural and Central Asian Populations Inferred from the Data on Alu Polymorphism

NineAlu loci (Ya5NBC5, Ya5NBC27, Ya5NBC148, Ya5NBC182, YA5NBC361, ACE, ApoA1, PV92, TPA25) were analyzed in six ethnic populations (Trans-Ural Bashkirs, Tatars-Mishars, Mordovians-Moksha, Mountain Maris, Udmurts, and Komi-Permyaks) of the Volga–Ural region and in three Central Asian populations (Uzbeks, Kazakhs, and Uigurs). All Alu insertions analyzed appeared to be polymorphic in all populations examined. The frequency of insertion varied from 0.110 in Mountain Maris at the Ya5NBC5 locus to 0.914 in Tatars at the ApoA1 locus. The data on the allele frequency distribution at nine loci point to the existence of substantial genetic diversity in the populations examined. The value of the observed heterozygosity averaged over nine Alu insertions varied from 0.326 in Mountain Maris to 0.445 in Kazakhs and Uigurs. The level of the interpopulation genetic differences for the Volga–Ural population (F st = 0.061) was higher than for the populations of Central Asia (F st = 0.024), Europe (F st = 0.02), and Southeastern Asia (F st = 0.018). The populations examined were highly differentiated both in respect of linguistic characteristics and the geographical position. The data obtained confirmed the effectiveness of the marker system used for the assessment of genetic differentiation and the relationships between the ethnic groups.

Analysis of Polymorphisms of the Huntington Disease Gene in Ethnic Populations of the Volga–Ural Region

Eleven populations of the Volga–Ural region were analyzed with respect to three intragenic polymorphisms of the Huntington disease gene (IT15), including highly polymorphic (CAG)n and moderately polymorphic (CCG)n of exon 1 and neutral del2642 of exon 58. In the case of (CAG)n, 101 genotypes were observed, with genotype number varying from 15 in Southeastern Bashkirs to 34 in Mari. Allele diversity RS ranged from 9.70 in Southeastern Bashkirs to 18.00 in Chuvash, averaging 13.79 ± 2.12. The (CAG)n allele frequency distribution was unimodal and had a maximum at (CAG)17. In the case of (CCG)n, six alleles with 6–12 repeats were observed. RS was 4.13 ± 0.44, ranging from 3.73 in Udmurts to 4.99 in Tatars. In the case of del2642, allele del– was detected at a frequency 0.830 in Mari to 0.932 in Udmurts. Of all Volga–Ural ethnic populations, Finno-Ugric ones proved to be most heterogeneous with respect to the three polymorphisms, whereas Turkic populations and, in particular, Bashkirs were homogeneous. Microdifferentiation of the Volga–Ural populations corresponded to the European type.

Origins of Uralic-speaking populations: craniological evidence

Data on 55 modern cranial samples representing Uralic and other Eurasian populations were subjected to canonical variate (CV) and principal component (PC) analysis for 6 nonmetric and 14 metric traits, respectively. While PC1 and CV1 reveal strong east-to-west gradients among the Uralians, PC2 and CV2 separate most of them from the remaining groups, suggesting that they have descended from an ancestral proto-Uralian population. The biologically "Uralic" features survive in modern Uralic groups despite the fact that the initial split was followed by a long period of hybridization with widely dissimilar people. Our results confirm that the ancestors of many Turkish-speaking groups as well as the Yukaghirs belonged to the proto-Uralic community.

Polymorphism of Y-Chromosomal Diallelic Loci in Populations of the Volga–Ural Region

Three diallelic polymorphisms of human Y chromosome (DYS287(Y Alupolymorphism, YAP), T/C transition at the RBF5locus (Tat), and G/A transition at the LLY22locus) were studied in eight ethnic populations of the Volga–Ural region, representing Turkic branch of the Altai (Bashkirs, Tatars, and Chuvashes) and Finno-Ugric branch of the Uralic linguistic family (Maris, Mordovians, Udmurts, Komi-Zyryans, and Komi-Permyaks), and in the group of Slavic migrants, belonging to the Indo-European linguistic family (Russians). The Volga–Ural populations were characterized by a low frequency of the Y chromosome Aluinsertion. Examination of an association between the Alupolymorphism and Tatmutation revealed absolute YAP–/C linkage. Analysis of the haplotype frequency distribution patterns constructed from the data on the DYS287and RBF5polymorphisms revealed substantial differences between Udmurts and other populations. The differences were also observed between Komi-Zyryans and the populations of Bashkirs, Mordovians, Komi-Permyaks, and Russians. Analysis of the degree of genetic differentiation pointed to high level of genetic differentiation of the male lineages of the Finno–Ugric ethnic groups. The data on the linkage between the RBF5locus and the LLY22locus mutations indicated the common origin of the Tatmutationin Bashkirs, Mordovians, Udmurts, and Komi-Zyryans, and of a number of ancestralCallele-bearing Y chromosomes in Tatars, Maris, and Chuvashes.

Pilot study of the Urals population by tooth electron paramagnetic resonance dosimetry.

During 1949-1956, about 76 x 10(6)m3 of radioactive liquid waste containing a total activity of 10(17) Bq was discharged into the Techa River by the first Russian industrial nuclear facility Mayak. As a consequence, the population living in the river valley received considerable internal and external radiation doses. The results of a first application of electron paramagnetic resonance (EPR) of tooth enamel for a retrospective individual dose evaluation of the residents of the Techa riverside are presented. Three main contributions to the dose absorbed in tooth enamel have been considered: external exposure mainly from the Techa River sediments, internal exposure mainly due to 90Sr; and background radiation including all other sources of exposure except the Techa River. The teeth of 86 inhabitants of the town Kamensk-Uralskii were analysed to determine the age-dependent contribution of the background radiation to the enamel dose. For 22 residents of the middle and lower Techa riverside, measurements of the 90Sr whole-body content and EPR measurements of the absorbed dose in enamel were used to establish a correlation between these two quantities. Finally, absorbed doses in the enamel of five residents of the upper Techa riverside were determined by EPR method. Contributions of the background radiation and the internal 90Sr contamination were subtracted to determine the external exposure of the residents.

An approach to dose reconstruction for the Urals population.

Population exposure in the Urals region occurred due to the releases of radionuclides by the Mayak plutonium facility in the 1950's. The major sources of radioactive contamination were the discharges of liquid wastes into the Techa river (1949-1956); an explosion in the storage facility for high level radioactive wastes which formed the East Urals Radioactive Trace in 1957; and gaseous aerosol releases within the first decade of the facility's operation (1949-1957). The problems of dose reconstruction for the population exposed on the Techa river banks and East Urals Radioactive Trace are outlined. The initial data sets and basic models for dose reconstruction are described. The main tasks of the Techa River Dosimetry System Project and the approaches to individual internal and external dose reassessment are formulated.

Coat Color Polymorphism of Abert's Squirrel, Sciurus aberti, in Colorado

Coat color variation was studied in museum specimens and in nat- ural populations of Abert's squirrel (Sciurus aberti) in Colorado. The phanero- morphism was manifest in two phases, previously described as normal wild type gray (agouti) and classical melanism (nonagouti). The polymorphism was limited to the subspecies (S. a. ferreus) of the north central portion of the state. In the Rocky Mountain Front Range ponderosa pine (Pinus ponderosa) forests, the fre- quency of nonagouti morphs was 67.5 + 6.5% and differed from that observed in the 40,000 acre Black Forest, where nearly all squirrels were nonagouti (79/80). The polymorphism seems a balanced one with frequencies of morphs having been generally stable since the turn of the century. The frequency of the morphs did not obviously vary with elevation, temperature, humidity, evaporation and freeze data. Coat color is an important characteristic in the study of mammals. Mammals have a small selection of color pigments (carotene, haemo- globin and melanins) with the melanins most important. Although coat color variants have been reported for many species of wild mam- mals, of which some coat color genes are known, these generally do not meet examples of Ford's definition of genetic polymorphism. Ford (1940) defined genetic polymorphism as the occurrence to- gether in the same population of two or more discontinuous forms of a species in such proportions that the rarest of them cannot be main- tained merely by recurrent mutation. Huxley (1955) proposed the present convention of using the term morph to replace form and phase when referring to poly- morphic variation. The presence of polymorphism in natural demes provides researchers a basis for sorting and studying observable genetic variability of organisms so similar that they share a common gene pool. The most common type of pelage color polymorphism in mammals