Gene pool differences between northern and southern Altaians inferred from the data on Y-chromosomal haplogroups

Y-chromosomal haplogroups composition and frequencies were analyzed in Northern and Southern Altaians. In the gene pool of Altaians a total of 18 Y-chromosomal haplogroups were identified, including C3xM77, C3c, DxM15, E, F*, J2, I1a, I1b, K*, N*, N2, N3a, O3, P*, Q*, R1*, R1a1, and R1b3. The structured nature of the Altaic gene pool is determined by the presence of the Caucasoid and Mongoloid components, along with the ancient genetic substratum, marked by the corresponding Western and Eastern Eurasian haplogroups. Haplogroup R1a1 prevailed in both ethnic groups, accounting for about 53 and 38% of paternal lineages in Southern and Northern Altaians, respectively. This haplogroup is thought to be associated with the eastward expansion of early Indo-Europeans, and marks Caucasoid element in the gene pools of South Siberian populations. Similarly to haplogroup K*, the second frequent haplogroup Q* represents paleo-Asiatic marker, probably associated with the Ket and Samoyedic contributions to the Altaic gene pool. The presence of lineages N2 and N3a can be explained as the contribution of Finno--Ugric tribes, assimilated by ancient Turks. The presence of haplogroups C3xM77, C3c, N*, and 03 reflects the contribution of Central Asian Mongoloid groups. These haplogroups, probably, mark the latest movements of Mongolian migrants from the territory of contemporary Tuva and Mongolia. The data of factor analysis, variance analysis, cluster analysis, and phylogenetic analysis point to substantial genetic differentiation of Northern and Southern Altaians. The differences between Northern and Southern Altaians in the haplogroup composition, as well as in the internal haplotype structure were demonstrated.     

Structure of the gene pool of eastern Ukrainians from Y-chromosome haplogroups

Y chromosomes from representative sample of Eastern Ukrainians (94 individuals) were analyzed for composition and frequencies of haplogroups, defined by 11 biallelic loci located in non-recombining part of the chromosome (SRY1532, YAP, 92R7, DYF155S2, 12f2, Tat, M9, M17, M25, M89, and M56). In the Ukrainian gene, pool six haplogroups were revealed: E, F (including G and I), J, N3, P, and R1a1. These haplogroups were earlier detected in a study of Y-chromosome diversity on the territory of Europe as a whole. The major haplogroup in the Ukrainian gene pool, haplogroup R1a1 (earlier designated HG3), accounted for about 44% of all Y chromosomes in the sample examined. This haplogroup is thought to mark the migration patterns of the early Indo-Europeans and is associated with the distribution of the Kurgan archaeological culture. The second major haplogroup is haplogroup F (21.3%), which is a combination of the lineages differing by the time of appearance. Haplogroup P found with the frequency of 9.6%, represents the genetic contribution of the population originating from the ancient autochthonous population of Europe. Haplogroups J and E (11.7 and 4.2%, respectively) mark the migration patterns of the Middle-Eastern agriculturists during the Neolithic. The presence of the N3 lineage (9.6%) is likely explained by a contribution of the assimilated Finno-Ugric tribes. The data on the composition and frequencies of Y-chromosome haplogroups in the sample studied substantially supplement the existing picture of the male lineage distribution in the Eastern Slav population.     

Characterization of mitochondrial haplogroups in a large population-based sample from the United States

Mitochondrial DNA (mtDNA) haplogroups are valuable for investigations in forensic science, molecular anthropology, and human genetics. In this study, we developed a custom panel of 61 mtDNA markers for high-throughput classification of European, African, and Native American/Asian mitochondrial haplogroup lineages. Using these mtDNA markers, we constructed a mitochondrial haplogroup classification tree and classified 18,832 participants from the National Health and Nutrition Examination Surveys (NHANES). To our knowledge, this is the largest study to date characterizing mitochondrial haplogroups in a population-based sample from the United States, and the first study characterizing mitochondrial haplogroup distributions in self-identified Mexican Americans separately from Hispanic Americans of other descent. We observed clear differences in the distribution of maternal genetic ancestry consistent with proposed admixture models for these subpopulations, underscoring the genetic heterogeneity of the United States Hispanic population. The mitochondrial haplogroup distributions in the other self-identified racial/ethnic groups within NHANES were largely comparable to previous studies. Mitochondrial haplogroup classification was highly concordant with self-identified race/ethnicity (SIRE) in non-Hispanic whites (94.8 %), but was considerably lower in admixed populations including non-Hispanic blacks (88.3 %), Mexican Americans (81.8 %), and other Hispanics (61.6 %), suggesting SIRE does not accurately reflect maternal genetic ancestry, particularly in populations with greater proportions of admixture. Thus, it is important to consider inconsistencies between SIRE and genetic ancestry when performing genetic association studies. The mitochondrial haplogroup data that we have generated, coupled with the epidemiologic variables in NHANES, is a valuable resource for future studies investigating the contribution of mtDNA variation to human health and disease.     

Genetic diversity of the Khakass gene pool: Subethnic differentiation and the structure of Y-chromosome haplogroups

The structure of Khakass gene pool has been investigated: Y-chromosome haplogroup compositions and frequencies were described in seven population samples of two basic subethnic groups, Sagai and Kachins, from three geographically separated regions of the Khakass Republic. Eight haplogroups were detected in the Khakass gene pool: C3, E, N*, N1b, N1c, R1a1a, and R1b1b1. The haplogroup spectra and the genetic diversity by haplogroups and YSTR haplotypes differed significantly between Sagai and Kachins. Kachins had a low level of gene diversity, whereas the diversity of Sagai was similar to that of other South-Siberian ethnic groups. Sagai samples from the Askizskii district were very similar to each other, and so were two Kachin samples from the Shirinskii district, while Sagai samples from the Tashtypskii district differed considerably from each other. The contribution of intergroup differences among ethnic groups was high, indicating significant genetic differentiation among native populations in Khakassia. The Khakass gene pool was strongly differentiated both by haplogroup frequencies and by YSTR haplotypes within the N1b haplogroup. The frequencies of YSTR haplotypes within the chromosome Y haplogroups N1b, N1c, and R1a1 were determined and their molecular phylogeny was investigated. Factor and cluster analysis, as well as AMOVA, suggest that the Khakass gene pool is structured by territory and subethnic groups.     

The Multifaceted Origin of Taurine Cattle Reflected by the Mitochondrial Genome

A Neolithic domestication of taurine cattle in the Fertile Crescent from local aurochsen (Bos primigenius) is generally accepted, but a genetic contribution from European aurochsen has been proposed. Here we performed a survey of a large number of taurine cattle mitochondrial DNA (mtDNA) control regions from numerous European breeds confirming the overall clustering within haplogroups (T1, T2 and T3) of Near Eastern ancestry, but also identifying eight mtDNAs (1.3%) that did not fit in haplogroup T. Sequencing of the entire mitochondrial genome showed that four mtDNAs formed a novel branch (haplogroup R) which, after the deep bifurcation that gave rise to the taurine and zebuine lineages, constitutes the earliest known split in the mtDNA phylogeny of B. primigenius. The remaining four mtDNAs were members of the recently discovered haplogroup Q. Phylogeographic data indicate that R mtDNAs were derived from female European aurochsen, possibly in the Italian Peninsula, and sporadically included in domestic herds. In contrast, the available data suggest that Q mtDNAs and T subclades were involved in the same Neolithic event of domestication in the Near East. Thus, the existence of novel (and rare) taurine haplogroups highlights a multifaceted genetic legacy from distinct B. primigenius populations. Taking into account that the maternally transmitted mtDNA tends to underestimate the extent of gene flow from European aurochsen, the detection of the R mtDNAs in autochthonous breeds, some of which are endangered, identifies an unexpected reservoir of genetic variation that should be carefully preserved.     

Genetic diversity of Khakassian gene pool: subethnic differensiation and the structure of Y-chromosome haplogroups,

The structure of Khakass gene pool has been investigated: compositions and frequencies of Y-chromosome haplogroups were described in seven population samples of two basic subethnic groups--Sagays and Kachins from three territorially distanced regions of Khakassia Republic. Eight haplogroups: C3, E, N*, N1b, N1c, R1a1a and R1b1b1 have been determined in Khakass gene pool. Significant differences between Sagays and Kachins were shown in haplogroup spectra and a level of genetic diversity in haplogroups and YSTR-haplotypes. Kachin samples are characterized by a low value of gene diversity, whereas the level of Sagay diversity is similar to that of other South-Siberian ethnoses. Sagay samples from Askizsky region are very similar to each other just as two Kachin samples from Shirinsky region, while Sagay samples from Tashtypsky region greatly differ from each other. A great portion of intergroup differences was determined among different ethnic groups, which testifies to significant genetic differentiation of native populations in Khakassia. Khakass gene pool is greatly differentiated both in haplogroup frequencies and in YSTR-haplotypes within N1b haplogroup. Frequencies and molecular phylogenesis of YSTR-haplotypes were revealed within N1b, N1c and R1a1 haplogroups of Y-chromosome. We carried out comparative analysis of the data obtained. The results of factor, cluster and dispersion analyses are evidence of structuredness of Khakass gene pool according to territorial-subethnic principle.     

Gene Pool Structure of Eastern Ukrainians as Inferred from the Y-Chromosome Haplogroups

Y chromosomes from representative sample of Eastern Ukrainians (94 individuals) were analyzed for composition and frequencies of haplogroups, defined by 11 biallelic loci located in non-recombining part of the chromosome (SRY1532, YAP, 92R7, DYF155S2, 12f2, Tat, M9, M17, M25,M89, andM56). In the Ukrainian gene, pool six haplogroups were revealed: E, F (including G and I), J, N3, P, and R1a1. These haplogroups were earlier detected in a study of Y-chromosome diversity on the territory of Europe as a whole. The major haplogroup in the Ukrainian gene pool, haplogroup R1a1 (earlier designated HG3), accounted for about 44% of all Y chromosomes in the sample examined. This haplogroup is thought to mark the migration patterns of the early Indo-Europeans and is associated with the distribution of the Kurgan archaeological culture. The second major haplogroup is haplogroup F (21.3%), which is a combination of the lineages differing by the time of appearance. Haplogroup P found with the frequency of 9.6%, represents the genetic contribution of the population originating from the ancient autochthonous population of Europe. Haplogroups J and E (11.7 and 4.2%, respectively) mark the migration patterns of the Middle-Eastern agriculturists during the Neolithic. The presence of the N3 lineage (9.6%) is likely explained by a contribution of the assimilated Finno–Ugric tribes. The data on the composition and frequencies of Y-chromosome haplogroups in the sample studied substantially supplement the existing picture of the male lineage distribution in the Eastern Slav population.     

Excavating Y-chromosome haplotype strata in Anatolia

Analysis of 89 biallelic polymorphisms in 523 Turkish Y chromosomes revealed 52 distinct haplotypes with considerable haplogroup substructure, as exemplified by their respective levels of accumulated diversity at ten short tandem repeat (STR) loci. The major components (haplogroups E3b, G, J, I, L, N, K2, and R1; 94.1%) are shared with European and neighboring Near Eastern populations and contrast with only a minor share of haplogroups related to Central Asian (C, Q and O; 3.4%), Indian (H, R2; 1.5%) and African (A, E3*, E3a; 1%) affinity. The expansion times for 20 haplogroup assemblages was estimated from associated STR diversity. This comprehensive characterization of Y-chromosome heritage addresses many multifaceted aspects of Anatolian prehistory, including: (1) the most frequent haplogroup, J, splits into two sub-clades, one of which (J2) shows decreasing variances with increasing latitude, compatible with a northward expansion; (2) haplogroups G1 and L show affinities with south Caucasus populations in their geographic distribution as well as STR motifs; (3) frequency of haplogroup I, which originated in Europe, declines with increasing longitude, indicating gene flow arriving from Europe; (4) conversely, haplogroup G2 radiates towards Europe; (5) haplogroup E3b3 displays a latitudinal correlation with decreasing frequency northward; (6) haplogroup R1b3 emanates from Turkey towards Southeast Europe and Caucasia and; (7) high resolution SNP analysis provides evidence of a detectable yet weak signal (<9%) of recent paternal gene flow from Central Asia. The variety of Turkish haplotypes is witness to Turkey being both an important source and recipient of gene flow.     

Male lineages in South American native groups: evidence of M19 traveling south

With this study, we aimed to determine the different male ancestral components of two Native American communities from Argentina, namely Toba and Colla. The analysis of 27 Y-chromosome SNPs allowed us to identify seven different haplogroups in both samples. Chromosomes carrying the M3 mutation, which typically defines the Native American haplogroup Q1a3a, were seen most frequently in the Toba community (90%). Conversely, Q1a3a was represented in 34% of the Colla Y-chromosomes, whereas haplogroup R1b1, the main representative of western European populations, exhibited the highest frequency in this population (41%). Different M3 sublineages in the Toba community could be identified by observing point mutations at both DYS385 and M19 loci. A microvariant at DYS385, named 16.1, has been characterized, which helps to further subdivide Q1a3a. It is the first time the M19 mutated allele is described in a population from Argentina. This finding supports the old age of the lineages carrying the M19 mutation, but it contradicts the previous hypothesis that the M19 mutated allele is confined to only two Equatorial-Tucano population groups from the north region of South America. The detection of M19 further south than previously thought allows questioning of the hypothesis that this lineage serves as an example of isolation after colonization. This observation also affirms the strong genetic drift to which Native Americans have been subjected. Moreover, our study illustrates a heterogeneous contribution of Europeans to these populations and supports previous studies showing that most Native American groups were subjected to European admixture that primarily involved immigrant men.     

Gene-pool structure of Tuvinians inferred from Y-chromosome marker data

The gene-pool structure of Tuvinians was examined in terms of the composition and frequency of Y-chromosome haplogroups in five geographically distanct populations. In the Tuvinian gene pool, a total of 22 haplogroups were identified with six of these, which were the most frequent (C3c, C3*, N1b, N1c1, Q1a3, and R1a1a). It was demonstrated that eastern regions of Tuva were most different from the other regions in haplotype frequencies. The evaluation of genetic diversity based on the frequencies of biallelic haplogroups and YSTR haplotypes revealed very high diversity values for all samples. In general, the genetic diversity values identified in Tuvinians were the highest for the indigenous ethnic groups of Siberia. The evaluation of the genetic differentiation of the samples examined using the analysis of molecular variance (AMOVA) showed that the gene pool of Tuvinians was relatively poorly differentiated with respect to haplogroup frequencies. Phylogenetic analysis within haplogroup N1b revealed strong founder effect, i.e., reduced diversity and star-like phylogeny of the median network of haplotypes, which formed a separate subcluster exclusive to Tuvinians. It was demonstrated that, in Tuvinians, haplogroup N1c1 was the most heterogeneous in haplotype profile and consisted of three different haplotype clusters, demonstrating considerable differences of western population from the rest of the Tuva populations. Phylogenetic analysis of haplogroups revealed common components for Tuvinians, Khakasses, Altaians, and Mongols.     

Mitochondrial DNA polymorphisms associated with longevity in a Finnish population

Sequence variation in mitochondrial DNA (mtDNA) may cause slight differences both in the functioning of the respiratory chain and in free radical production, and an association between certain mtDNA haplogroups and longevity has been suggested. In order to determine further the role of mtDNA in longevity, we studied the frequencies of mtDNA haplogroups and haplogroup clusters among elderly subjects and controls in a Finnish population. Samples were obtained from 225 persons aged 90-91 years (Vitality 90+) and from 400 middle-aged controls and 257 infants. MtDNA haplogroups were determined by restriction fragment length polymorphism. The haplogroup frequencies of the Vitality 90+ group differed from both those of the middle-aged controls ( P=0.01) and the infants ( P=0.00005), haplogroup H being less frequent than among the middle-aged subjects ( P=0.001) and infants ( P=0.00001), whereas haplogroups U and J were more frequent. Haplogroup clusters also differed between Vitality 90+ and both the middle-aged subjects ( P=0.002) and infants ( P=0.00001), the frequency of haplogroup cluster HV being lower in the former and that of UK and WIX being higher. These data suggest an association between certain mtDNA haplogroups or haplogroup clusters and longevity. Furthermore, our data appear to favour the presence of advantageous polymorphisms and support a role for mitochondria and mtDNA in the degenerative processes involved in ageing.     

High-resolution SNPs and microsatellite haplotypes point to a single, recent entry of Native American Y chromosomes into the Americas

A total of 63 binary polymorphisms and 10 short tandem repeats (STRs) were genotyped on a sample of 2,344 Y chromosomes from 18 Native American, 28 Asian, and 5 European populations to investigate the origin(s) of Native American paternal lineages. All three of Greenberg's major linguistic divisions (including 342 Amerind speakers, 186 Na-Dene speakers, and 60 Aleut-Eskimo speakers) were represented in our sample of 588 Native Americans. Single-nucleotide polymorphism (SNP) analysis indicated that three major haplogroups, denoted as C, Q, and R, accounted for nearly 96% of Native American Y chromosomes. Haplogroups C and Q were deemed to represent early Native American founding Y chromosome lineages; however, most haplogroup R lineages present in Native Americans most likely came from recent admixture with Europeans. Although different phylogeographic and STR diversity patterns for the two major founding haplogroups previously led to the inference that they were carried from Asia to the Americas separately, the hypothesis of a single migration of a polymorphic founding population better fits our expanded database. Phylogenetic analyses of STR variation within haplogroups C and Q traced both lineages to a probable ancestral homeland in the vicinity of the Altai Mountains in Southwest Siberia. Divergence dates between the Altai plus North Asians versus the Native American population system ranged from 10,100 to 17,200 years for all lineages, precluding a very early entry into the Americas.     

Analysis of mtDNA variation in African populations reveals the most ancient of all human continent-specific haplogroups.

mtDNA sequence variation was examined in 140 Africans, including Pygmies from Zaire and Central African Republic (C.A.R.) and Mandenkalu, Wolof, and Pular from Senegal. More than 76% of the African mtDNAs (100% of the Pygmies and 67.3% of the Senegalese) formed one major mtDNA cluster (haplogroup L) defined by an African-specific HpaI site gain at nucleotide pair (np) 3592. Additional mutations subdivided haplogroup L into two subhaplogroups, each encompassing both Pygmy and Senegalese mtDNAs. A novel 12-bp homoplasmic insertion in the intergenic region between tRNA(Tyr) and cytochrome oxidase I (COI) genes was also observed in 17.6% of the Pygmies from C.A.R. This insertion is one of the largest observed in human mtDNAs. Another 25% of the Pygmy mtDNAs harbored a 9-bp deletion between the cytochrome oxidase II (COII) and tRNA(Lys) genes, a length polymorphism previously reported in non-African populations. In addition to haplogroup L, other haplogroups were observed in the Senegalese. These haplogroups were more similar to those observed in Europeans and Asians than to haplogroup L mtDNAs, suggesting that the African mtDNAs without the HpaI np 3592 site could be the ancestral types from which European and Asian mtDNAs were derived. Comparison of the intrapopulation sequence divergence in African and non-African populations confirms that African populations exhibit the largest extent of mtDNA variation, a result that further supports the hypothesis that Africans represent the most ancient human group and that all modern humans have a common and recent African origin. The age of the total African variation was estimated to be 101,000-133,000 years before present (YBP), while the age of haplogroup L was estimated at 98,000-130,000 YBP. These values substantially exceed the ages of all Asian- and European-specific mtDNA haplogroups.     

The origin of Yakuts: analysis of Y-chromosome haplotypes

Gene pool structure of Sakha Republic (Yakutia) native population has been studied: we defined composition and frequencies of Y-chromosome haplogroups for Yakuts. Six haplogroups: C3 x M77, C3c, N*, N2, N3a and R1a1 have been revealed in Yakut gene pool. A greater part of Y-chromosome in Yakut population belongs to N3a haplogroup (89%). All investigated Yakut population samples have low values of gene diversity, calculated based on haplogroup frequencies. Gene differentiation of the investigated samples estimated using the analysis of molecular variance (AMOVA) by two marker systems (haplogroup frequencies and microsatellite haplotypes of Y-chromosome) revealed a portion of interpopulation differences amounting to 0.24 and 2.85%, respectively. Frequencies and molecular phylogeny of YSTR-haplotypes were revealed for N3a haplogroup of Y-chromosome. Altogether forty haplotypes were found in Yakuts. Evenks and Yakuts are characterized by overlapping and very specific spectrum of N3a haplotypes, which is not typical for other Siberian ethnic groups. Cluster analysis of populations by N3a YSTR-haplotypes shows Yakut isolation from Turkic-speaking populations in the South Siberia. Genetic diversity generation time for a specific spectrum of Yakut haplotypes was estimated as 4.45 +/- 1.96 thousand years. As opposed to the data on mtDNA, the obtained results give an evidence for significant contribution of a local palaeolithic component into Y-chromosomal Yakut gene pool. Ethnogenetic reconstruction of the present picture of genetic diversity in N3a haplogroup in the territory of Siberia is under consideration.     

山东汉、回族男性人群父系遗传结构研究

本研究基于75个Y-SNP位点和23个Y-STR基因座对山东汉、回族男性人群进行研究,旨在揭示两个人群的父系遗传结构,为法医学应用及群体遗传学等提供基础数据。研究基于微测序技术检测187份山东汉族和130份山东回族样本,获取75个Y-SNP位点分型;采用PowerPlex^®Y23试剂盒检测23个Y-STR基因座;采用直接计数法统计等位基因频率、单倍型频率及单倍群频率,根据公式D=n(1-∑pi²)/(n-1)计算基因多样性、单倍型多样性以及单倍群多样性;根据Median-joining方法,使用NETWORK 5.0和NETWORK Publisher构建并展示网络图。研究结果显示,单倍群O-M175、C-M130、N-M231、Q-M242为山东汉族男性人群主要的Y单倍群,单倍群O-M175、J-M304、R-M207、C-M130、N-M231为山东回族男性人群最主要的单倍群;23个Y-STR基因座在山东汉族男性样本中检出187种单倍型,单倍型多样性为1.0000,在山东回族中检出121种单倍型,单倍型多样性为0.9988;网络图显示同一Y单倍群的样本相对独立地聚集在一起,山东汉族与回族人群之间存在共享单倍群,同时也存在一些特异性单倍群,如单倍群J-M304、R-M207均以山东回族为主,单倍群Q-M242则以山东汉族为主。山东汉族和回族男性人群的主要单倍群均为单倍群O-M175;单倍群J-M304、R-M207在山东回族中的高频分布,单倍群Q-M242则在山东汉族中高频分布。研究表明山东回族人群中保留有一定比例的欧亚西部和中东特有的Y染色体类型。     

The Enigmatic Origin of Bovine mtDNA Haplogroup R: Sporadic Interbreeding or an Independent Event of Bos primigenius Domestication in Italy?

Background

When domestic taurine cattle diffused from the Fertile Crescent, local wild aurochsen (Bos primigenius) were still numerous. Moreover, aurochsen and introduced cattle often coexisted for millennia, thus providing potential conditions not only for spontaneous interbreeding, but also for pastoralists to create secondary domestication centers involving local aurochs populations. Recent mitochondrial genomes analyses revealed that not all modern taurine mtDNAs belong to the shallow macro-haplogroup T of Near Eastern origin, as demonstrated by the detection of three branches (P, Q and R) radiating prior to the T node in the bovine phylogeny. These uncommon haplogroups represent excellent tools to evaluate if sporadic interbreeding or even additional events of cattle domestication occurred.

Methodology

The survey of the mitochondrial DNA (mtDNA) control-region variation of 1,747 bovine samples (1,128 new and 619 from previous studies) belonging to 37 European breeds allowed the identification of 16 novel non-T mtDNAs, which after complete genome sequencing were confirmed as members of haplogroups Q and R. These mtDNAs were then integrated in a phylogenetic tree encompassing all available P, Q and R complete mtDNA sequences.

Conclusions

Phylogenetic analyses of 28 mitochondrial genomes belonging to haplogroups P (N = 2), Q (N = 16) and R (N = 10) together with an extensive survey of all previously published mtDNA datasets revealed major similarities between haplogroups Q and T. Therefore, Q most likely represents an additional minor lineage domesticated in the Near East together with the founders of the T subhaplogroups. Whereas, haplogroup R is found, at least for the moment, only in Italy and nowhere else, either in modern or ancient samples, thus supporting an origin from European aurochsen. Haplogroup R could have been acquired through sporadic interbreeding of wild and domestic animals, but our data do not rule out the possibility of a local and secondary event of B. primigenius domestication in Italy.     

Gene pool differences between Northern and Southern Altaians inferred from the data on Y-chromosomal haplogroups

Y-chromosomal haplogroups composition and frequencies were analyzed in Northern and Southern Altaians. In the gene pool of Altaians a total of 18 Y-chromosomal haplogroups were identified, including C3xM77, C3c, DxM15, E, F^*, J2, I1a, I1b, K^*, N^*, N2, N3a, O3, P^*, Q^*, R1^*, R1a1, and R1b3. The structuring nature of the Altaic gene pool is determined by the presence of the Caucasoid and Mongoloid components, along with the ancient genetic substratum, marked by the corresponding Western and Eastern Eurasian haplogroups. Haplogroup R1a1 prevailed in both ethnic groups, accounting for about 53 and 38% of paternal lineages in Southern and Northern Altaians, respectively. This haplogroup is thought to be associated with the eastward expansion of early Indo-Europeans, and marks Caucasoid element in the gene pools of South Siberian populations. Similarly to haplogroup K^*, the second frequent haplogroup Q^* represents paleo-Asiatic marker, probably associated with the Ket and Samoyedic contributions to the Altaic gene pool. The presence of lineages N2 and N3a can be explained as the contribution of Finno-Ugric tribes, assimilated by ancient Turks. The presence of haplogroups C3xM77, C3c, N^*, and O3 reflects the contribution of Central Asian Mongoloid groups. These haplogroups, probably, mark the latest movements of Mongolian migrants from the territory of contemporary Tuva and Mongolia. The data of factor analysis, variance analysis, cluster analysis, and phylogenetic analysis point to substantial genetic differentiation of Northern and Southern Altaians. The differences between Northern and Southern Altaians in the haplogroup composition, as well as in the internal haplotype structure were demonstrated.     

Linkage disequilibrium mapping of Arabidopsis CRY2 flowering time alleles

The selfing plant Arabidopsis thaliana has been proposed to be well suited for linkage disequilibrium (LD) mapping as a means of identifying genes underlying natural trait variation. Here we apply LD mapping to examine haplotype variation in the genomic region of the photoperiod receptor CRYPTOCHROME2 and associated flowering time variation. CRY2 DNA sequences reveal strong LD and the existence of two highly differentiated haplogroups (A and B) across the gene; in addition, a haplotype possessing a radical glutamine-to-serine replacement (AS) occurs within the more common haplogroup. Growth chamber and field experiments using an unstratified population of 95 ecotypes indicate that under short-day photoperiod, the AS and B haplogroups are both highly significantly associated with early flowering. Data from six genes flanking CRY2 indicate that these haplogroups are limited to an approximately 65-kb genomic region around CRY2. Whereas the B haplogroup cannot be delimited to <16 kb around CRY2, the AS haplogroup is characterized almost exclusively by the nucleotide polymorphisms directly associated with the serine replacement in CRY2; this finding strongly suggests that the serine substitution is directly responsible for the AS early flowering phenotype. This study demonstrates the utility of LD mapping for elucidating the genetic basis of natural, ecologically relevant variation in Arabidopsis.     

Linguistic and maternal genetic diversity are not correlated in Native Mexicans

Mesoamerica, defined as the broad linguistic and cultural area from middle southern Mexico to Costa Rica, might have played a pivotal role during the colonization of the American continent. The Mesoamerican isthmus has constituted an important geographic barrier that has severely restricted gene flow between North and South America in pre-historical times. Although the Native American component has been already described in admixed Mexican populations, few studies have been carried out in native Mexican populations. In this study, we present mitochondrial DNA (mtDNA) sequence data for the first hypervariable region (HVR-I) in 477 unrelated individuals belonging to 11 different native populations from Mexico. Almost all of the Native Mexican mtDNAs could be classified into the four pan-Amerindian haplogroups (A2, B2, C1, and D1); only two of them could be allocated to the rare Native American lineage D4h3. Their haplogroup phylogenies are clearly star-like, as expected from relatively young populations that have experienced diverse episodes of genetic drift (e.g., extensive isolation, genetic drift, and founder effects) and posterior population expansions. In agreement with this observation, Native Mexican populations show a high degree of heterogeneity in their patterns of haplogroup frequencies. Haplogroup X2a was absent in our samples, supporting previous observations where this clade was only detected in the American northernmost areas. The search for identical sequences in the American continent shows that, although Native Mexican populations seem to show a closer relationship to North American populations, they cannot be related to a single geographical region within the continent. Finally, we did not find significant population structure in the maternal lineages when considering the four main and distinct linguistic groups represented in our Mexican samples (Oto-Manguean, Uto-Aztecan, Tarascan, and Mayan), suggesting that genetic divergence predates linguistic diversification in Mexico.