Reconstructing the evolutionary history of China: a caveat about inferences drawn from ancient DNA

The decipherment of the meager information provided by short fragments of ancient mitochondrial DNA (mtDNA) is notoriously difficult but is regarded as a most promising way toward reconstructing the past from the genetic perspective. By haplogroup-specific hypervariable segment (HVS) motif search and matching or near-matching with available modern data sets, most of the ancient mtDNAs can be tentatively assigned to haplogroups, which are often subcontinent specific. Further typing for mtDNA haplogroup-diagnostic coding region polymorphisms, however, is indispensable for establishing the geographic/genetic affinities of ancient samples with less ambiguity. In the present study, we sequenced a fragment (approximately 982 bp) of the mtDNA control region in 76 Han individuals from Taian, Shandong, China, and we combined these data with previously reported samples from Zibo and Qingdao, Shandong. The reanalysis of two previously published ancient mtDNA population data sets from Linzi (same province) then indicates that the ancient populations had features in common with the modern populations from south China rather than any specific affinity to the European mtDNA pool. Our results highlight that ancient mtDNA data obtained under different sampling schemes and subject to potential contamination can easily create the impression of drastic spatiotemporal changes in the genetic structure of a regional population during the past few thousand years if inappropriate methods of data analysis are employed.     

Differentiation of mitochondrial DNA and Y chromosomes in Russian populations

The genetic composition of the Russian population was investigated by analyzing both mitochondrial DNA (mtDNA) and Y-chromosome loci polymorphisms that allow for the different components of a population gene pool to be studied, depending on the mode of DNA marker inheritance. mtDNA sequence variation was examined by using hypervariable segment I (HVSI) sequencing and restriction analysis of the haplogroup-specific sites in 325 individuals representing 5 Russian populations from the European part of Russia. The Y-chromosome variation was investigated in 338 individuals from 8 Russian populations (including 5 populations analyzed for mtDNA variation) using 12 binary markers. For both uniparental systems most of the observed haplogroups fell into major West Eurasian haplogroups (97.9% and 99.7% for mtDNA and Y-chromosome haplogroups, respectively). Multidimensional scaling analysis based on pairwise F(ST) values between mtDNA HVSI sequences in Russians compared to other European populations revealed a considerable heterogeneity of Russian populations; populations from the southern and western parts of Russia are separated from eastern and northern populations. Meanwhile, the multidimensional scaling analysis based on Y-chromosome haplogroup F(ST) values demonstrates that the Russian gene pool is close to central-eastern European populations, with a much higher similarity to the Baltic and Finno-Ugric male pools from northern European Russia. This discrepancy in the depth of penetration of mtDNA and Y-chromosome lineages characteristic for the most southwestern Russian populations into the east and north of eastern Europe appears to indicate that Russian colonization of the northeastern territories might have been accomplished mainly by males rather than by females.     

mtDNA haplogroup distribution in Chinese patients with Leber's hereditary optic neuropathy and G11778A mutation

Mitochondrial DNA background has been shown to be involved in the penetrance of Leber’s hereditary optic neuropathy (LHON) in western Eurasian populations. To analyze mtDNA haplogroup distribution pattern in Han Chinese patients with LHON and G11778A mutation, we analyzed the mtDNA haplogroups of 41 probands with LHON known to harbor G11778A mutation by sequencing the mtDNA control region hypervariable segments and some coding region polymorphisms. Each mtDNA was classified according to the available East Asian haplogroup system. The haplogroup distribution pattern of LHON sample was then compared to the reported Han Chinese samples. Haplogroups M7, D, B, and A were detected in 11 (26.8%), 10 (24.4%), 8 (19.5%), and 5 (12.2%) LHON families, respectively, and accounted for 82.9% of the total samples examined. For the remaining seven mtDNAs, six belonged to M8a, M10a, C, N9a, F1a, and R11, respectively, and one could only be assigned into macro-haplogroup M. The LHON sample was distinguished from other Han Chinese samples in the principal component map based on haplogroup distribution frequency. Our results show that matrilineal genetic components of Chinese LHON patients with G11778A are diverse and differ from related Han Chinese regional samples. mtDNA background might affect the expression of LHON and the G11778A mutation in Chinese population.     

The emerging limbs and twigs of the East Asian mtDNA tree

We determine the phylogenetic backbone of the East Asian mtDNA tree by using published complete mtDNA sequences and assessing both coding and control region variation in 69 Han individuals from southern China. This approach assists in the interpretation of published mtDNA data on East Asians based on either control region sequencing or restriction fragment length polymorphism (RFLP) typing. Our results confirm that the East Asian mtDNA pool is locally region-specific and completely covered by the two superhaplogroups M and N. The phylogenetic partitioning based on complete mtDNA sequences corroborates existing RFLP-based classification of Asian mtDNA types and supports the distinction between northern and southern populations. We describe new haplogroups M7, M8, M9, N9, and R9 and demonstrate by way of example that hierarchically subdividing the major branches of the mtDNA tree aids in recognizing the settlement processes of any particular region in appropriate time scale. This is illustrated by the characteristically southern distribution of haplogroup M7 in East Asia, whereas its daughter-groups, M7a and M7b2, specific for Japanese and Korean populations, testify to a presumably (pre-)Jomon contribution to the modern mtDNA pool of Japan.     

Phylogeny of mitochondrial DNA macrohaplogroup N in India, based on complete sequencing: implications for the peopling of South Asia

To resolve the phylogeny of the autochthonous mitochondrial DNA (mtDNA) haplogroups of India and determine the relationship between the Indian and western Eurasian mtDNA pools more precisely, a diverse subset of 75 macrohaplogroup N lineages was chosen for complete sequencing from a collection of >800 control-region sequences sampled across India. We identified five new autochthonous haplogroups (R7, R8, R30, R31, and N5) and fully characterized the autochthonous haplogroups (R5, R6, N1d, U2a, U2b, and U2c) that were previously described only by first hypervariable segment (HVS-I) sequencing and coding-region restriction-fragment-length polymorphism analysis. Our findings demonstrate that the Indian mtDNA pool, even when restricted to macrohaplogroup N, harbors at least as many deepest-branching lineages as the western Eurasian mtDNA pool. Moreover, the distribution of the earliest branches within haplogroups M, N, and R across Eurasia and Oceania provides additional evidence for a three-founder-mtDNA scenario and a single migration route out of Africa.     

Mitochondrial DNA diversity and population differentiation in southern East Asia

Mitochondrial DNA (mtDNA) polymorphism has been studied systematically in the Han, Tibeto-Buman, and Hmong-Mien ethnic families of southern East Asia. Only two families in this region, Daic and Austro-Asiatic, were still uninvestigated. Daic is a major ethnic family in South China and Southeast Asia and has a long history. To study mtDNA polymorphism within this family, all the Daic populations of China and some of Vietnam (774 individuals from 30 populations) were typed by HVS-1 region sequencing and by PCR-RFLP assays. The observed high Southern type frequencies (B, F, M7, R) confirmed Daic as a typical Southern group. mtDNAs of other populations (126 individuals from 14 populations) from Austro-Asiatic ethnic families neighboring the Daic were also typed. Networks of mtDNA haplogroups in South China were traced from these new data and those from the literature. Ethnic families share many haplogroups, indicating their common origin. However, the two largest families in South China, Daic, and Hmong-Mien, polarized into several ethnic family specific haplogroups. Haplogroup ages were estimated in the networks of high-frequency haplogroups (B, F, M7, R), and they were found to originate about 50,000 years ago. In contrast, ethnic family specific haplogroups all originated around 20,000 years ago. We therefore conclude that modern humans have lived in South China for a long time, inside-ethnogenesis was a rather late event, and frequent inmixing was taking place throughout. MtDNA data of Daic, Austro-Asiatic and other populations in South China has therefore proven pivotal for studying the human history of East Asia.     

Different matrilineal contributions to genetic structure of ethnic groups in the silk road region in china

Previous studies have shown that there were extensive genetic admixtures in the Silk Road region. In the present study, we analyzed 252 mtDNAs of five ethnic groups (Uygur, Uzbek, Kazak, Mongolian, and Hui) from Xinjiang Province, China (through which the Silk Road once ran) together with some reported data from the adjacent regions in Central Asia. In a simple way, we classified the mtDNAs into different haplogroups (monophyletic clades in the rooted mtDNA tree) according to the available phylogenetic information and compared their frequencies to show the differences among the matrilineal genetic structures of these populations with different demographic histories. With the exception of eight unassigned M*, N*, and R* mtDNAs, all the mtDNA types identified here belonged to defined subhaplogroups of haplogroups M and N (including R) and consisted of subsets of both the eastern and western Eurasian pools, thus providing direct evidence supporting the suggestion that Central Asia is the location of genetic admixture of the East and the West. Although our samples were from the same geographic location, a decreasing tendency of the western Eurasian-specific haplogroup frequency was observed, with the highest frequency present in Uygur (42.6%) and Uzbek (41.4%) samples, followed by Kazak (30.2%), Mongolian (14.3%), and Hui (6.7%). No western Eurasian type was found in Han Chinese samples from the same place. The frequencies of the eastern Eurasian-specific haplogroups also varied in these samples. Combined with the historical records, ethno-origin, migratory history, and marriage customs might play different roles in shaping the matrilineal genetic structure of different ethnic populations residing in this region.     

Ancient DNA evidence supports the contribution of Di‐Qiang people to the han Chinese gene pool

Han Chinese is the largest ethnic group in the world. During its development, it gradually integrated with many neighboring populations. To uncover the origin of the Han Chinese, ancient DNA analysis was performed on the remains of 46 humans (～1700 to 1900 years ago) excavated from the Taojiazhai site in Qinghai province, northwest of China, where the Di‐Qiang populations had previously lived. In this study, eight mtDNA haplogroups (A, B, D, F, M*, M10, N9a, and Z) and one Y‐chromosome haplogroup (O3) were identified. All analyses show that the Taojiazhai population presents close genetic affinity to Tibeto‐Burman populations (descendants of Di‐Qiang populations) and Han Chinese, suggesting that the Di‐Qiang populations may have contributed to the Han Chinese genetic pool. Am J Phys Anthropol, 2011. © 2010 Wiley‐Liss, Inc.     

Traces of archaic mitochondrial lineages persist in Austronesian-speaking Formosan populations

Genetic affinities between aboriginal Taiwanese and populations from Oceania and Southeast Asia have previously been explored through analyses of mitochondrial DNA (mtDNA), Y chromosomal DNA, and human leukocyte antigen loci. Recent genetic studies have supported the “slow boat” and “entangled bank” models according to which the Polynesian migration can be seen as an expansion from Melanesia without any major direct genetic thread leading back to its initiation from Taiwan. We assessed mtDNA variation in 640 individuals from nine tribes of the central mountain ranges and east coast regions of Taiwan. In contrast to the Han populations, the tribes showed a low frequency of haplogroups D4 and G, and an absence of haplogroups A, C, Z, M9, and M10. Also, more than 85% of the maternal lineages were nested within haplogroups B4, B5a, F1a, F3b, E, and M7. Although indicating a common origin of the populations of insular Southeast Asia and Oceania, most mtDNA lineages in Taiwanese aboriginal populations are grouped separately from those found in China and the Taiwan general (Han) population, suggesting a prevalence in the Taiwanese aboriginal gene pool of its initial late Pleistocene settlers. Interestingly, from complete mtDNA sequencing information, most B4a lineages were associated with three coding region substitutions, defining a new subclade, B4a1a, that endorses the origin of Polynesian migration from Taiwan. Coalescence times of B4a1a were 13.2 ± 3.8 thousand years (or 9.3 ± 2.5 thousand years in Papuans and Polynesians). Considering the lack of a common specific Y chromosomal element shared by the Taiwanese aboriginals and Polynesians, the mtDNA evidence provided here is also consistent with the suggestion that the proto-Oceanic societies would have been mainly matrilocal.     

Origins of domestic dog in southern East Asia is supported by analysis of Y-chromosome DNA

Global mitochondrial DNA (mtDNA) data indicates that the dog originates from domestication of wolf in Asia South of Yangtze River (ASY), with minor genetic contributions from dog-wolf hybridisation elsewhere. Archaeological data and autosomal single nucleotide polymorphism data have instead suggested that dogs originate from Europe and/or South West Asia but, because these datasets lack data from ASY, evidence pointing to ASY may have been overlooked. Analyses of additional markers for global datasets, including ASY, are therefore necessary to test if mtDNA phylogeography reflects the actual dog history and not merely stochastic events or selection. Here, we analyse 14,437 bp of Y-chromosome DNA sequence in 151 dogs sampled worldwide. We found 28 haplotypes distributed in five haplogroups. Two haplogroups were universally shared and included three haplotypes carried by 46% of all dogs, but two other haplogroups were primarily restricted to East Asia. Highest genetic diversity and virtually complete phylogenetic coverage was found within ASY. The 151 dogs were estimated to originate from 13-24 wolf founders, but there was no indication of post-domestication dog-wolf hybridisations. Thus, Y-chromosome and mtDNA data give strikingly similar pictures of dog phylogeography, most importantly that roughly 50% of the gene pools are shared universally but only ASY has nearly the full range of genetic diversity, such that the gene pools in all other regions may derive from ASY. This corroborates that ASY was the principal, and possibly sole region of wolf domestication, that a large number of wolves were domesticated, and that subsequent dog-wolf hybridisation contributed modestly to the dog gene pool.     

Paternal origins of Chinese cattle

To determine the genetic diversity and paternal origin of Chinese cattle, 302 males from 16 Chinese native cattle breeds as well as 30 Holstein males and four Burma males as controls were analysed using four Y‐SNPs and two Y‐STRs. In Chinese bulls, the taurine Y1 and Y2 haplogroups and indicine Y3 haplogroup were detected in seven, 172 and 123 individuals respectively, and these frequencies varied among the Chinese cattle breeds examined. Y2 dominates in northern China (91.4%), and Y3 dominates in southern China (90.8%). Central China is an admixture zone, although Y2 predominates overall (72.0%). The geographical distributions of the Y2 and Y3 haplogroup frequencies revealed a pattern of male indicine introgression from south to north China. The three Y haplogroups were further classified into one Y1 haplotype, five Y2 haplotypes and one Y3 haplotype in Chinese native bulls. Due to the interplay between taurine and indicine types, Chinese cattle represent an extensive reservoir of genetic diversity. The Y haplotype distribution of Chinese cattle exhibited a clear geographical structure, which is consistent with mtDNA, historical and geographical information.     

Phylogeny of east Asian mitochondrial DNA lineages inferred from complete sequences

The now-emerging mitochondrial DNA (mtDNA) population genomics provides information for reconstructing a well-resolved mtDNA phylogeny and for discerning the phylogenetic status of the subcontinentally specific haplogroups. Although several major East Asian mtDNA haplogroups have been identified in studies elsewhere, some of the most basal haplogroups, as well as numerous minor subhaplogroups, were not yet determined or fully characterized. To fill the lacunae, we selected 48 mtDNAs from >2,000 samples across China for complete sequencing that cover virtually all (sub)haplogroups discernible to date in East Asia. This East Asian mtDNA phylogeny can henceforth serve as a solid basis for phylogeographic analyses of mtDNAs, as well as for studies of mitochondrial diseases in East and Southeast Asia.     

MtDNA haplogroups M7 and B in southwestern Han Chinese at risk for acute mountain sickness

We conducted a case-control study to investigate the association of mitochondrial DNA (mtDNA) haplogroups with acute mountain sickness (AMS) in Han Chinese from southwestern (SW) China. Pearson's chi-square test or Fisher's exact test revealed significant reduction of mtDNA haplogroups D and M9, while a significant increase of haplogroup M7 in AMS subjects compared with non-AMS subjects. The multivariate logistic regression analysis after adjustment for body mass index (BMI), a risk factor of AMS in the present study, showed that both D and M9 were associated with significantly decreased risk of AMS, while M7 was associated with a significantly increased risk of AMS (OR=0.605, p=0.000; OR=0.037, p=0.001, and OR=2.419, p=0.001, respectively). In addition, further analysis stratified by the AMS severities indicated that haplogroup B was correlated with a 2.41-folds increased risk of developing severe AMS (95%C.I=1.288-4.514, p=0.006). Our findings provide evidence that, in SW Han Chinese, mtDNA haplogroups D and M9 are related to individual tolerance to AMS, while haplogroups M7 and B are risk factors for AMS.     

Complete mitochondrial DNA analysis of eastern Eurasian haplogroups rarely found in populations of northern Asia and eastern Europe

With the aim of uncovering all of the most basal variation in the northern Asian mitochondrial DNA (mtDNA) haplogroups, we have analyzed mtDNA control region and coding region sequence variation in 98 Altaian Kazakhs from southern Siberia and 149 Barghuts from Inner Mongolia, China. Both populations exhibit the prevalence of eastern Eurasian lineages accounting for 91.9% in Barghuts and 60.2% in Altaian Kazakhs. The strong affinity of Altaian Kazakhs and populations of northern and central Asia has been revealed, reflecting both influences of central Asian inhabitants and essential genetic interaction with the Altai region indigenous populations. Statistical analyses data demonstrate a close positioning of all Mongolic-speaking populations (Mongolians, Buryats, Khamnigans, Kalmyks as well as Barghuts studied here) and Turkic-speaking Sojots, thus suggesting their origin from a common maternal ancestral gene pool. In order to achieve a thorough coverage of DNA lineages revealed in the northern Asian matrilineal gene pool, we have completely sequenced the mtDNA of 55 samples representing haplogroups R11b, B4, B5, F2, M9, M10, M11, M13, N9a and R9c1, which were pinpointed from a massive collection (over 5000 individuals) of northern and eastern Asian, as well as European control region mtDNA sequences. Applying the newly updated mtDNA tree to the previously reported northern Asian and eastern Asian mtDNA data sets has resolved the status of the poorly classified mtDNA types and allowed us to obtain the coalescence age estimates of the nodes of interest using different calibrated rates. Our findings confirm our previous conclusion that northern Asian maternal gene pool consists of predominantly post-LGM components of eastern Asian ancestry, though some genetic lineages may have a pre-LGM/LGM origin.     

Phylogeographic analysis of mitochondrial DNA in northern Asian populations

To elucidate the human colonization process of northern Asia and human dispersals to the Americas, a diverse subset of 71 mitochondrial DNA (mtDNA) lineages was chosen for complete genome sequencing from the collection of 1,432 control-region sequences sampled from 18 autochthonous populations of northern, central, eastern, and southwestern Asia. On the basis of complete mtDNA sequencing, we have revised the classification of haplogroups A, D2, G1, M7, and I; identified six new subhaplogroups (I4, N1e, G1c, M7d, M7e, and J1b2a); and fully characterized haplogroups N1a and G1b, which were previously described only by the first hypervariable segment (HVS1) sequencing and coding-region restriction-fragment-length polymorphism analysis. Our findings indicate that the southern Siberian mtDNA pool harbors several lineages associated with the Late Upper Paleolithic and/or early Neolithic dispersals from both eastern Asia and southwestern Asia/southern Caucasus. Moreover, the phylogeography of the D2 lineages suggests that southern Siberia is likely to be a geographical source for the last postglacial maximum spread of this subhaplogroup to northern Siberia and that the expansion of the D2b branch occurred in Beringia ~7,000 years ago. In general, a detailed analysis of mtDNA gene pools of northern Asians provides the additional evidence to rule out the existence of a northern Asian route for the initial human colonization of Asia.     

Mitochondrial DNA haplogroup M7 confers a reduced risk of colorectal cancer in a Han population from northern China

Mitochondria are central eukaryotic organelles in cellular metabolism and ATP production. Mitochondrial DNA (mtDNA) alterations have been implicated in the development of colorectal cancer (CRC). However, there are few reports on the association between mtDNA haplogroups or single nucleotide polymorphisms (SNPs) and the risk of CRC. The mtDNA of 286 Northern Han Chinese CRC patients were sequenced by next-generation sequencing technology. MtDNA data from 811 Han Chinese population controls were collected from two public data sets. Then, logistic regression analysis was used to determine the effect of mtDNA haplogroup or SNP on the risk of CRC. We found that patients with haplogroup M7 exhibited a reduced risk of CRC when compared to patients with other haplogroups (odds ratio [OR] = 0.532, 95% confidence interval [CI] = 0.285–0.937, p = 0.036) or haplogroup B (OR = 0.477, 95% CI = 0.238–0.916, p = 0.030). Furthermore, haplogroup M7 was still associated with the risk of CRC when the validation and combined control cohort were used. In addition, several haplogroup M7 specific SNPs, including 199T>C, 4071C>T and 6455C>T, were significantly associated with the risk of CRC. Our results indicate the risk potential of mtDNA haplogroup M7 and SNPs in CRC in Northern China.     

Phylogeography of the brown hare (Lepus europaeus) in Europe: a legacy of south‐eastern Mediterranean refugia?

Aim We analysed the population genetics of the brown hare (Lepus europaeus) in order to test the hypothesis that this species migrated into central Europe from a number of late glacial refugia, including some in Asia Minor. Location Thirty‐three localities in Greece, Bulgaria, Italy, Croatia, Serbia, Poland, Switzerland, Austria, France, Germany, the Netherlands, Spain, the United Kingdom, Turkey and Israel. Methods In total, 926 brown hares were analysed for mitochondrial DNA (mtDNA) variation by restriction fragment length polymorphism (RFLP) performed on polymerase chain reaction‐amplified products spanning cytochrome b (cyt b)/control region (CR), cytochrome oxidase I (COI) and 12S–16S rRNA. In addition, sequence analysis of the mtDNA CR‐I region was performed on 69 individuals, and the data were compared with 137 mtDNA CR‐I sequences retrieved from GenBank. Results The 112 haplotypes detected were partitioned into five phylogeographically well‐defined major haplogroups, namely the ‘south‐eastern European type haplogroup’ (SEEh), ‘Anatolian/Middle Eastern type haplogroup’ (AMh), ‘European type haplogroup, subgroup A’ (EUh‐A), ‘European type haplogroup, subgroup B’ (EUh‐B) and ‘Intermediate haplogroup’ (INTERh). Sequence data retrieved from GenBank were consistent with the haplogroups determined in this study. In Bulgaria and north‐eastern Greece numerous haplotypes of all five haplogroups were present, forming a large overlap zone. Main conclusions The mtDNA results allow us to infer post‐glacial colonization of large parts of Europe from a late glacial/early Holocene source population in the central or south‐central Balkans. The presence of Anatolian/Middle Eastern haplotypes in the large overlap zone in Bulgaria and north‐eastern Greece reveals gene flow from Anatolia to Europe across the late Pleistocene Bosporus land‐bridge. Although various restocking operations could be partly responsible for the presence of unexpected haplotypes in certain areas, we nevertheless trace a strong phylogeographic signal throughout all regions under study. Throughout Europe, mtDNA results indicate that brown hares are not separated into discernable phyletic groups.     

The ancestry of Brazilian mtDNA lineages

We have analyzed 247 Brazilian mtDNAs for hypervariable segment (HVS)-I and selected restriction fragment-length-polymorphism sites, to assess their ancestry in different continents. The total sample showed nearly equal amounts of Native American, African, and European matrilineal genetic contribution but with regional differences within Brazil. The mtDNA pool of present-day Brazilians clearly reflects the imprints of the early Portuguese colonization process (involving directional mating), as well as the recent immigrant waves (from Europe) of the last century. The subset of 99 mtDNAs from the southeastern region encompasses nearly all mtDNA haplogroups observed in the total Brazilian sample; for this regional subset, HVS-II was analyzed, providing, in particular, some novel details of the African mtDNA phylogeny.     

Most of the extant mtDNA boundaries in South and Southwest Asia were likely shaped during the initial settlement of Eurasia by anatomically modern humans

Background

Recent advances in the understanding of the maternal and paternal heritage of south and southwest Asian populations have highlighted their role in the colonization of Eurasia by anatomically modern humans. Further understanding requires a deeper insight into the topology of the branches of the Indian mtDNA phylogenetic tree, which should be contextualized within the phylogeography of the neighboring regional mtDNA variation. Accordingly, we have analyzed mtDNA control and coding region variation in 796 Indian (including both tribal and caste populations from different parts of India) and 436 Iranian mtDNAs. The results were integrated and analyzed together with published data from South, Southeast Asia and West Eurasia.

Results

Four new Indian-specific haplogroup M sub-clades were defined. These, in combination with two previously described haplogroups, encompass approximately one third of the haplogroup M mtDNAs in India. Their phylogeography and spread among different linguistic phyla and social strata was investigated in detail. Furthermore, the analysis of the Iranian mtDNA pool revealed patterns of limited reciprocal gene flow between Iran and the Indian sub-continent and allowed the identification of different assemblies of shared mtDNA sub-clades.

Conclusions

Since the initial peopling of South and West Asia by anatomically modern humans, when this region may well have provided the initial settlers who colonized much of the rest of Eurasia, the gene flow in and out of India of the maternally transmitted mtDNA has been surprisingly limited. Specifically, our analysis of the mtDNA haplogroups, which are shared between Indian and Iranian populations and exhibit coalescence ages corresponding to around the early Upper Paleolithic, indicates that they are present in India largely as Indian-specific sub-lineages. In contrast, other ancient Indian-specific variants of M and R are very rare outside the sub-continent.     

凉地方牛群体母系遗传背景研究

黄牛（Bos taurus）的驯养作为农耕文化重要内容之一,在我国历史悠久,长久以来形成的役用型逐步被肉用型所替代。为了揭示平凉地方牛群体的遗传背景,分析其是否具有生产优质牛肉的遗传基础,本研究测定了88头平凉地方牛群体mtDNA D-loop HVS序列,并对包括平凉地方牛群体在内的我国23个地方牛群体单倍型分布及系统发生关系进行了分析。结果表明,mtDNA D-loop 高变区,在平凉地方牛群体共有52个单倍型,而23个地方牛群体共有95个单倍型,这些单倍型在系统发生树和中介网络关系中分布于两个分枝,即瘤牛型和普通牛进化枝。因此,我们认为平凉地方牛群体和我国其他牛种一样,存在普通牛和瘤牛两个母系起源的遗传背景。