Tracing the legacy of the early Hainan Islanders--a perspective from mitochondrial DNA

Malaria resistance-related biological adaptation and complex evolutionary footprints inferred from one integrative Tai-Kadai-related genomic resource

Pathogen‒host adaptative interactions and complex population demographical processes, including admixture, drift, and Darwen selection, have considerably shaped the Neolithic-to-Modern Western Eurasian population structure and genetic susceptibility to modern human diseases. However, the genetic footprints of evolutionary events in East Asia remain unknown due to the underrepresentation of genomic diversity and the design of large-scale population studies. We reported one aggregated database of genome-wide SNP variations from 796 Tai-Kadai (TK) genomes, including that of Bouyei first reported here, to explore the genetic history, population structure, and biological adaptative features of TK people from southern China and Southeast Asia. We found geography-related population substructure among TK people using the state-of-the-art population genetic structure reconstruction techniques based on the allele frequency spectrum and haplotype-resolved phased fragments. We found that the northern TK people from Guizhou harbored one TK-dominant ancestry maximized in the Bouyei people, and the southern TK people from Thailand were more influenced by Southeast Asians and indigenous people. We reconstructed fitted admixture models and demographic graphs, which showed that TK people received gene flow from ancient southern rice farmer-related lineages related to the Hmong-Mien and Austroasiatic people and from northern millet farmers associated with the Sino-Tibetan people. Biological adaptation focused on our identified unique TK lineages related to Bouyei, which showed many adaptive signatures conferring Malaria resistance and low-rate lipid metabolism. Further gene enrichment, the allele frequency distribution of derived alleles, and their correlation with the incidence of Malaria further confirmed that CR1 played an essential role in the resistance of Malaria in the ancient "Baiyue" tribes.

The maternal phylogenetic insights of Yunnan Miao group revealed by complete mitogenomes

The Miao group is one of the representative Hmong-Mien-speaking populations and primarily scattered in southern China and Southeast Asia, which has experienced massive migrations in history and thus forms distinctive evolutionary genetics. Yet, the genetic explorations of Miao group are relatively limited based on complete mitochondrial genome (mitogenome), especially for the Miao group from Yunnan Province (YNM). Here, we sequenced complete mitogenomes of 132 Miao individuals from Yunnan Province using massively parallel sequencing method. Total 132 Miao individuals could be allocated to 119 various haplotypes, which were mainly dominated by haplogroups prevalent in southern East Asia (B, F, M7 and R9), and rarely occupied by northern lineages (A, D, G and M8). In order to dissect the genetic background of YNM more comprehensively, we introduced 99 published population data with 7135 complete mitochondrial sequences for population genetic comparisons. YNM exhibited closer genetic relationships with Hmong-Mien, Tai-Kadai, Sino-Tibetan and Austroasiatic populations, especially for Hmong-Mien populations; we further speculated that Miao group might have certain direct or indirect gene exchanges with ancient Baiyue groups. Several maternal lineages, such as B5a1c1a, F1g1, B4a5 and D4e1a3, were found to be specifically shared by YNM and other Hmong-Mien populations, and these matrilineal expansions occurred roughly during the Neolithic period. Eventually, according to the population dynamic analyses of YNM, the population size began to emerge recovery ∼1-0.5 kya after a long-term population reduction ∼1-5 kya, during which the B5a1c1a haplogroup manifested relatively apparent lineage expansion.

Extensive genetic admixture between Tai-Kadai-speaking people and their neighbours in the northeastern region of the Yungui Plateau inferred from genome-wide variations

BACKGROUND

Yungui Plateau in Southwest China is characterized by multi-language and multi-ethnic communities and is one of the regions with the wealthiest ethnolinguistic, cultural and genetic diversity in East Asia. There are numerous Tai-Kadai (TK)-speaking populations, but their detailed evolutionary history and biological adaptations are still unclear.

RESULTS

Here, we genotyped genome-wide SNP data of 77 unrelated TK-speaking Zhuang and Dong individuals from the Yungui Plateau and explored their detailed admixture history and adaptive features using clustering patterns, allele frequency differentiation and sharing haplotype patterns. TK-speaking Zhuang and Dong people in Guizhou are closely related to geographically close TK and Hmong-Mien (HM)-speaking populations. Besides, we identified that Guizhou TK-speaking people have a close genetic relationship with Austronesian (AN)-speaking Atayal and Paiwan people, which is supported by the common origin of the ancient Baiyue tribe. We additionally found subtle genetic differences among the newly studied TK people and previously reported Dais via the fine-scale genetic substructure analysis based on the shared haplotype chunks. Finally, we identified specific selection candidate signatures associated with several essential human immune systems and neurological disorders, which could provide evolutionary evidence for the allele frequency distribution pattern of genetic risk loci.

CONCLUSIONS

Our comprehensive genetic characterization of TK people suggested the strong genetic affinity within TK groups and extensive gene flow with geographically close HM and Han people. We also provided genetic evidence that supported the common origin hypothesis of TK and AN people. The best-fitted admixture models further suggested that ancestral sources from northern millet farmers and southern inland and coastal people contributed to the formation of the gene pool of the Zhuang and Dong people.

Diversity and distribution of mitochondrial DNA in non-Austronesian-speaking Taiwanese individuals

Many studies have described the diversity of Austronesian-speaking Taiwanese people to shed more light on their origin and their connection with the "Out of Taiwan" migrations. However, the genetic relationship between the non-Austronesian-speaking groups of Taiwan and the populations of continental Asia is still unclear. Here, we studied the diversity of mtDNA in 767 non-Austronesian speakers from 16 locations in Taiwan using partial sequencing obtained from the hypervariable segment I (HVS-I) and coding regions 8,001-9,000 and 9.801-10,900 and 85 complete mtDNA genome sequences. Bayesian analysis of population structure was used to examine their relationship with over 3662 individuals representing indigenous groups of Taiwan, continental East Asia, Japan, and Island Southeast Asia. The whole analysis identified 278 haplotypes. Complete genomes revealed 62 novel subhaplogroups, of which 31 were exclusive to Taiwan. Estimates of coalescence times of all subhaplogroups showed peaks of diversification greater than 5.0 kya, likely characterizing gene flow from continental East Asian groups but not excluding in situ Taiwanese ancestry. Furthermore, a significant number of clades exclusive to non-Austronesian speakers of Taiwan (NAN_Tw) showed coalescence peaks between 1.0 and 2.6 kya, suggesting possible late Neolithic to early metal age settlements of NAN_Tw and local expansion in Taiwan.

Tracing Bai-Yue Ancestry in Aboriginal Li People on Hainan Island

As the most prevalent aboriginal group on Hainan Island located between South China and the mainland of Southeast Asia, the Li people are believed to preserve some unique genetic information due to their isolated circumstances, although this has been largely uninvestigated. We performed the first whole-genome sequencing of 55 Hainan Li (HNL) individuals with high coverage (∼30-50×) to gain insight into their genetic history and potential adaptations. We identified the ancestry enriched in HNL (∼85%) is well preserved in present-day Tai-Kadai speakers residing in South China and North Vietnam, that is, Bai-Yue populations. A lack of admixture signature due to the geographical restriction exacerbated the bottleneck in the present-day HNL. The genetic divergence among Bai-Yue populations began ∼4,000-3,000 years ago when the proto-HNL underwent migration and the settling of Hainan Island. Finally, we identified signatures of positive selection in the HNL, some outstanding examples included FADS1 and FADS2 related to a diet rich in polyunsaturated fatty acids. In addition, we observed that malaria-driven selection had occurred in the HNL, with population-specific variants of malaria-related genes (e.g., CR1) present. Interestingly, HNL harbors a high prevalence of malaria leveraged gene variants related to hematopoietic function (e.g., CD3G) that may explain the high incidence of blood disorders such as B-cell lymphomas in the present-day HNL. The results have advanced our understanding of the genetic history of the Bai-Yue populations and have provided new insights into the adaptive scenarios of the Li people.

The evolutionary dynamics and epidemiological history of hepatitis C virus genotype 6, including unique strains from the Li community of Hainan Island, China

Hepatitis C virus (HCV) is a highly diverse pathogen that frequently establishes a chronic long-term infection, but the origins and drivers of HCV diversity in the human population remain unclear. Previously unidentified strains of HCV genotype 6 (gt6) were recently discovered in chronically infected individuals of the Li ethnic group living in Baisha County, Hainan Island, China. The Li community, who were early settlers on Hainan Island, has a distinct host genetic background and cultural identity compared to other ethnic groups on the island and mainland China. In this report, we generated 33 whole virus genome sequences to conduct a comprehensive molecular epidemiological analysis of these novel gt6 strains in the context of gt6 isolates present in Southeast Asia. With the exception of one gt6a isolate, the Li gt6 sequences formed three novel clades from two lineages which constituted 3 newly assigned gt6 subtypes and 30 unassigned strains. Using Bayesian inference methods, we dated the most recent common ancestor for all available gt6 whole virus genome sequences to approximately 2767 bce (95 per cent highest posterior density (HPD) intervals, 3670-1397 bce), which is far earlier than previous estimates. The substitution rate was 1.20 × 10-4 substitutions/site/year (s/s/y), and this rate varied across the genome regions, from 1.02 × 10-5 s/s/y in the 5'untranslated region (UTR) region to 3.07 × 10-4 s/s/y in E2. Thus, our study on an isolated ethnic minority group within a small geographical area of Hainan Island has substantially increased the known diversity of HCV gt6, already acknowledged as the most diverse HCV genotype. The extant HCV gt6 sequences from this study were probably transmitted to the Li through at least three independent events dating perhaps from around 4,000 years ago. This analysis describes deeper insight into basic aspects of HCV gt6 molecular evolution including the extensive diversity of gt6 sequences in the isolated Li ethnic group.

Genome-Wide Evidence for Complex Hybridization and Demographic History in a Group of Cycas From China

Cycads represent one of the most ancestral living seed plants as well as one of the most threatened plant groups in the world. South China is a major center and potential origin of Cycas, the most rapidly diversified lineage of cycads. However, genomic-wide diversity of Cycas remains poorly understood due to the challenge of generating genomic markers associated with their inherent large genomes. Here, we perform a comprehensive conservation genomic study based on restriction-site associated DNA sequencing (RADseq) data in six representative species of Cycas in South China. Consistently low genetic diversity and strong genetic differentiation were detected across species. Both phylogenetic inference and genetic structure analysis via several methods revealed generally congruent groups among the six Cycas species. The analysis with ADMIXTURE showed low mixing of genetic composition among species, while individuals of C. dolichophylla exhibited substantial genetic admixture with C. bifida, C. changjiangensis, and C. balansae. Furthermore, the results from Treemix, f₄-statistic, and ABBA-BABA test were generally consistent and revealed the complex patterns of interspecific gene flow. Relatively strong signals of hybridization were detected between C. dolichophylla and C. szechuanensis, and the ancestor of C. taiwaniana and C. changjiangensis. Distinct patterns of demographic history were inferred for these species by Stairway Plot, and our results suggested that both climate fluctuation and frequent geological activities during the late Pleistocene exerted deep impacts on the population dynamics of these species in South China. Finally, we explore the practical implications of our findings for the development of conservation strategies in Cycas. The present study demonstrates the efficiency of RADseq for conservation genomic studies on non-model species with large and complex genomes. Given the great significance of cycads as a radical transition in the evolution of plant biodiversity, our study provides important insights into the mechanisms of diversification in such recently radiated living fossil taxa.

Positive relationships among aboveground biomass, tree species diversity, and urban greening management in tropical coastal city of Haikou

Within urban green spaces, tree species diversity is believed to correlate with aboveground biomass, though there is some disagreement within the literature on the strength and directionality of the relationship. Therefore, we assessed the relationship between the biodiversity of woody species and the aboveground biomass of woody plant species in the tropical, coastal city of Haikou in southern China. To accomplish this, we obtained comprehensive tree and site data through field sampling of 190 urban functional units (UFUs, or work units) corresponding to six types of land uses governmental-institutional, industrial-commercial, park-recreational, residential, transport infrastructure, and undeveloped area. Based on our field data, we investigated the relationship between tree species diversity and aboveground biomass using multiple regression, which revealed significant relationships across all five types of land uses. Aboveground biomass in green spaces was also correlated with anthropogenic factors, especially time since urban development, or site age, annual maintenance frequency by human caretakers, and human population density. Among these factors, maintenance is the strongest predictor of aboveground biomass in urban green space. Therefore, this study highlights the critical role of maintenance of urban green space in promoting both aboveground biomass and woody biodiversity in urban ecosystems and, consequently, on urban ecosystem services. Our findings contribute to a deeper understanding of the ecosystem services provided by communities of woody plant species in urban areas.

The forensic landscape and the population genetic analyses of Hainan Li based on massively parallel sequencing DNA profiling

Due to the formation of the Qiongzhou Strait by climate change and marine transition, Hainan island was isolated from the mainland southern China during the Last Glacial Maximum. Hainan island, located at the southernmost part of China and separated from the Leizhou Peninsula by the Qiongzhou Strait, laid on one of the modern human northward migration routes from Southeast Asia to East Asia. The Hlai language-speaking Li minority, the second largest population after Han Chinese in Hainan island, is the direct descendants of the initial migrants in Hainan island and has unique ethnic properties and derived characteristics; however, the forensic-associated studies on Hainan Li population are still insufficient. Hence, 136 Hainan Li individuals were genotyped in this study using the MPS-based ForenSeq™ DNA Signature Prep Kit (DNA Primer Set A, DPMA) to characterize the forensic genetic polymorphism landscape, and DNA profiles were obtained from 152 different molecular genetic markers (27 autosomal STRs, 24 Y-STRs, 7 X-STRs, and 94 iiSNPs). A total of 419 distinct length variants and 586 repeat sequence sub-variants, with 31 novel alleles (at 17 loci), were identified across the 58 STR loci from the DNA profiles of Hainan Li population. We evaluated the forensic characteristics and efficiencies of DPMA, demonstrating that the STRs and iiSNPs in DPMA were highly polymorphic in Hainan Li population and could be employed in forensic applications. In addition, we set up three datasets, which included the genetic data of (i) iiSNPs (27 populations, 2640 individuals), (ii) Y-STRs (42 populations, 8281 individuals), and (iii) Y haplogroups (123 populations, 4837 individuals) along with the population ancestries and language families, to perform population genetic analyses separately from different perspectives. In conclusion, the phylogenetic analyses indicated that Hainan Li, with a southern East Asia origin and Tai-Kadai language-speaking language, is an isolated population relatively. But the genetic pool of Hainan Li influenced by the limited gene flows from other Tai-Kadai populations and Hainan populations. Furthermore, the establishment of isolated population models will be beneficial to clarify the exquisite population structures and develop specific genetic markers for subpopulations in forensic genetic fields.

The Genetic Structure of Chinese Hui Ethnic Group Revealed by Complete Mitochondrial Genome Analyses Using Massively Parallel Sequencing

Mitochondrial DNA (mtDNA), coupled with maternal inheritance and relatively high mutation rates, provides a pivotal way for us to investigate the formation histories of populations. The Hui minority with Islamic faith is one of the most widely distributed ethnic groups in China. However, the exploration of Hui's genetic architecture from the complete mitochondrial genome perspective has not been detected yet. Therefore, in this study, we employed the complete mitochondrial genomes of 98 healthy and unrelated individuals from Northwest China, as well as 99 previously published populations containing 7274 individuals from all over the world as reference data, to comprehensively dissect the matrilineal landscape of Hui group. Our results demonstrated that Hui group exhibited closer genetic relationships with Chinese Han populations from different regions, which was largely attributable to the widespread of haplogroups D4, D5, M7, B4, and F1 in these populations. The demographic expansion of Hui group might occur during the Late Pleistocene. Finally, we also found that Hui group might have gene exchanges with Uygur, Tibetan, and Tajik groups in different degrees and retained minor genetic imprint of European-specific lineages, therefore, hinting the existence of multi-ethnic integration events in shaping the genetic landscape of Chinese Hui group.

Massively parallel sequencing of mitogenome sequences reveals the forensic features and maternal diversity of tai-kadai-speaking hlai islanders

As a single maternally inherited locus, human mitochondrial DNA (mtDNA) is geographically arranged and plays a key role in forensic applications. Hlai population has been evidenced as the most typical and unmixed representative of the Tai-Kadai-speaking populations via genome-wide analyses. However, forensic features and maternal diversity of the complete mitogenomes in this Tai-Kadai ancestrally related population are scarce. Thus, we sequenced the complete mitogenomes in 127 Hainan Hlais and found 109 distinct haplotypes belonging to 43 terminal haplogroups resulting in the haplotype diversity of 0.9970. Our results of comprehensive population comparisons showed that Hlai islanders had a close genetic affinity with Tai-Kadai-speaking populations from Southeast Asia, which is consistent with the back-migration of Chinese Neolithic farmers into this region via the inland route. Besides, maternally genetic evidence further revealed a close genetic relationship between Tai-Kadai-speaking and Austronesian-speaking populations when only East Asian dataset was considered, which is consistent with the common origin from Yangtze rice farmers and then spread southward along the inland and coastal routes, respectively. In the reconstructed phylogenetic tree and median-joining networks, the vast majority of Hlais were clustered in exclusive clades, which demonstrated that Hlai people probably had undergone founder effect or genetic bottleneck in their history, and remained genetically isolated for a long time. Collectively, Hainan Hlai did not exhibit detectable maternal gene flow from surrounding or incoming populations. Mitogenome information generated in this study is a contribution in mitigating the underrepresentation of Chinese data in forensic mitogenetics and will assist geography-, metapopulation-, as well as phylogeny-based queries.

Inferring the population history of Tai-Kadai-speaking people and southernmost Han Chinese on Hainan Island by genome-wide array genotyping

Hainan Island, located between East Asia and Southeast Asia, represents an ideal region for the study of the genetic architecture of geographically isolated populations. However, the genetic structure and demographic history of the indigenous Tai-Kadai-speaking Hlai people and recent expanded southernmost Han Chinese on this island are poorly characterized due to a lack of genetic data. Thus, we collected and genotyped 36 Qiongzhong Hlai and 48 Haikou Han individuals at 497,637 single nucleotide polymorphisms (SNPs). We applied principal component analysis, ADMIXTURE, symmetrical D-statistics, admixture-f₃ statistics, qpWave, and qpAdm analysis to infer the population history. Our results revealed the East Asian populations are characterized by a north-south genetic cline with Hlai at the southernmost end. We have not detected recent gene flow from neighboring populations into Hlai, therefore, we used Hlai as an unadmixed proxy to model the admixture history of mainland Tai-Kadai-speaking populations and southern Han Chinese. The mainland Tai-Kadai-speaking populations are suggested deriving a larger number of their ancestry from Hlai-related lineage, but also having admixture from South Asian-related or other neighboring populations. The Hlai group is also suggested to contribute about half of the ancestry to Han Chinese in Hainan. The complex patterns of genetic structure in East Asia were shaped via language categories, geographical boundaries, and large southward population movements with language dispersal and agriculture propagation.

Forensic features, genetic diversity and structure analysis of three Chinese populations using 47 autosomal InDels

Insertion/deletion polymorphisms (InDels), which combine the desirable features of both short tandem repeats (STRs) and single-nucleotide polymorphisms (SNPs), have become widely used genetic markers for forensic investigations, anthropology and population genetics. The AGCU InDel 50 kit is a newly developed panel that contains 47 autosomal InDels (A-InDels), 2 Y-chromosomal InDels (Y-InDels) and Amelogenin and is designed to provide a higher discriminatory power in Chinese populations compared with the Qiagen DIPplex kit. In this study, 542 unrelated individuals were first genotyped to evaluate the forensic efficiency of this novel panel in three Chinese ethnicities (Hainan Han, Hainan Li and Zunyi Gelao groups). Additionally, genetic relationships among the three investigated populations (geographically close but linguistically different populations: Han and Li; geographically diverse but from the same language family: Li and Gelao) and 31 worldwide populations were analyzed using pairwise genetic distances, multidimensional scaling (MDS), phylogenetic tree, principal component analysis (PCA) and STRUCTURE. The combined powers of discrimination (CPD) for the Han, Li and Gelao groups were 0.999999999999999999635, 0.999999999999999997668 and 0.999999999999999999840, respectively, and the combined powers of exclusion (CPE) were 0.999715, 0.999283 and 0.999575, respectively. The genetic relationship between the Hainan Han and Zunyi Gelao groups was relatively closer than that between the Hainan Li and Zunyi Gelao groups, demonstrating that there was little gene communication between Li and Han living on Hainan Island as well as between Li and Gelao in the Tai-Kadai language family. The aforementioned results suggest that the AGCU InDel 50 kit is an effective tool that is appropriate for personal identification and population genetics.

Genetic diversity and phylogenetic analysis of Chinese Han and Li ethnic populations from Hainan Island by 30 autosomal insertion/deletion polymorphisms

With the characteristics of low mutation rate, length variation and short amplicon size, insertion/deletion polymorphisms (InDels) have the advantages of both short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs). Herein, people of two ethnicities from Hainan Island were genotyped for the first time using the Investigator DIPplex kit. We investigated the forensic parameters of the 30 InDels and the phylogenetic relationships among different populations. The accumulated powers of discrimination and powers of exclusion were 0.999 999 999 9646 and 0.9897 in the Hainan Han population and 0.999 999 999 9292 and 0.9861 in the Hainan Li population, respectively. Additionally, population comparisons among geographically, ethnically and linguistically diverse populations via cluster heatmap, multidimensional scaling, principal component analysis, phylogenetic tree and STRUCTURE analyses demonstrated that the Hainan Han population had genetic similarities to the other Han, She and Tujia populations, while the Hainan Li population had close genetic relationships to the Zhuang and Miao groups; both populations had a high degree of genetic differentiation from most Turkic-speaking populations. Aforementioned results suggested that the 30 autosomal InDels are highly polymorphic and informative, which are suitable for human identification and population genetics.

Four hundred and forty-five Chinese individuals from two ethnicities (Hainan Han and Hainan Li) were firstly analyzed by 30 autosomal InDels included in the Investigator DIPplex panel.

Forensic parameters of the 30 InDels in the two populations showed high polymorphism and universality for human identification purposes.

The Investigator DIPplex panel had a certain capacity of differentiating intercontinental populations and different language populations.

Whole mitochondrial genome analysis of highland Tibetan ethnicity using massively parallel sequencing

Mitochondrial DNA (mtDNA) is a key player in numerous multifaceted and intricate biological processes and plays a pivotal role in dissecting the peopling of different populations, due to its maternally inherited property and comparatively high mutation rate. In this study, 119 Tibetan individuals from the Muli Tibetan Autonomous County of China (average altitude above 3,000 m) were employed in mitochondrial genome (mitogenome) sequencing by massively parallel sequencing (MPS) techniques using the Precision ID mtDNA Whole Genome Panel on an Ion S5XL system. The dataset presented 88 distinct haplotypes, resulting in the haplotype diversity of 0.9909. The majority of haplotypes were assigned to East Asian lineages and the distribution of haplogroups of Muli Tibetan significantly differed from reference Tibetan populations. The maximum parsimony phylogeny reconstructed by 119 newly generated mitogenomes revealed 12 major Muli Tibetan lineages. Intriguingly, a Sherpa-specific sub-haplogroup A15c1 with the lack of mutations at 4216 and 15,924 was discerned in our dataset, which suggested that the maternal gene pool of Sherpas may derive from Tibetan populations. The shared haplogroups between Muli Tibetan and lowland Han Chinese hinted that these lineages may derive from non-Tibetans and have already differentiated before their arrival on the Tibetan Plateau. Furthermore, extensive pairwise population comparisons displayed that Muli Tibetan had a closer genetic relationship with ethnically or linguistically close Nyingtri Tibetan, Nyingtri Lhoba and Chamdo Tibetan populations. Genetic affinity was also observed between the Muli Tibetan and North Han Chinese. Collectively, the results generated in this study enriched the existing forensic mtDNA database and raised additional interest in the application of whole mitogenome sequencing in forensic investigations.

Genetic diversity of 23 STR loci in Guangxi Zhuang population and its phylogenetic relationship with 25 other populations

Aim: To estimate genetic diversity of 23 STR loci included in the DNA Typer^TM 25 Kit, and evaluate its effectiveness in forensic application.Subjects and methods: A total of 450 (251 males and 179 females) unrelated healthy individuals from Guangxi Zhuang population were amplified with DNA Typer^TM 25 Kit, isolated by the 3730 Series Genetic Analyzer^TM, and genotyped using the GeneMapper ID-X. Genetic parameters and population relationships were analysed.Results: Allele frequencies ranged from 0.001 to 0.5889. The combined power of discrimination (CPD) and the combined power of exclusion (CPE) of the 23 STR loci were 0.999999999999999999 and 0.999996765, respectively. No deviations from Hardy-Weinberg equilibrium and linkage disequilibrium were observed. Inter-population comparison based on Fst, PCA, genetic distance, phylogenetic trees, and MDS showed that Zhuang population clustered with the populations holding a close geographic distance with Zhuang (Guangdong Han and Hainan Li populations).Conclusions: Our study indicated that the 23 autosomal STR loci included in DNA Typer^TM 25 Kit can be used as forensic tools for individual identification and parentage testing. Moreover, the result of our mass investigation will enrich the forensic database of Chinese populations and serve for further study of the origin of anthropology.

Genetic variability and forensic efficiency of 39 microsatellite loci in the Li ethnic group from Hainan Island in the South China Sea

BACKGROUND

Investigation of allele and genotype frequencies of microsatellite loci in various populations is an essential pre-requisite in forensic application.

AIM

The present study obtained population genetic data and forensic parameters of 39 autosomal Short Tandem Repeats (STRs) loci from a Chinese Li ethnic group and estimated the genetic relationships between Li and other reference populations.

SUBJECTS AND METHODS

Thirty-nine STR loci, which include D19S433, D5S818, D21S11, D18S51, D6S1043, D3S1358, D13S317, D7S820, D16S539, CSF1PO, Penta D, D2S441, vWA, D8S1179, TPOX, Penta E, TH01, D12S391, D2S1338, FGA, D6S477, D18S535, D19S253, D15S659, D11S2368, D20S470, D1S1656, D22-GATA198B05, D8S1132, D4S2366, D21S1270, D13S325, D9S925, D3S3045, D14S608, D10S1435, D7S3048, D17S1290 and D5S2500, were amplified in two multiplex DNA-STR fluorescence detection systems for 189 unrelated healthy individuals of the Chinese Li ethnic group. The allele frequency distribution and several parameters commonly used in forensic science were statistically analysed.

RESULTS

A total of 378 alleles were observed with corresponding allelic frequencies ranging from 0.0026-0.5899. The power of discrimination and power of exclusion ranged from 0.7569-0.9672 and 0.2513-0.7355, respectively. The power of exclusion (PE) ranged from 0.2580-0.7943 for trio paternity cases and 0.1693-0.5940 for duo paternity cases. The polymorphism information content (PIC) ranged from 0.5001-0.8611. The cumulative match probability across these 39 loci was 2.4242 × 10^-38.

CONCLUSION

The results indicate that 39 STR loci are polymorphic among the Li ethnic group in Hainan Island in the South China Sea. This set of polymorphic STR loci provide highly polymorphic information and forensic efficiency for forensic individual identification and paternity testing, as well as basic population data for population genetics and anthropological research.

Carriers of human mitochondrial DNA macrohaplogroup M colonized India from southeastern Asia

Background

From a mtDNA dominant perspective, the exit from Africa of modern humans to colonize Eurasia occurred once, around 60 kya, following a southern coastal route across Arabia and India to reach Australia short after. These pioneers carried with them the currently dominant Eurasian lineages M and N. Based also on mtDNA phylogenetic and phylogeographic grounds, some authors have proposed the coeval existence of a northern route across the Levant that brought mtDNA macrohaplogroup N to Australia. To contrast both hypothesis, here we reanalyzed the phylogeography and respective ages of mtDNA haplogroups belonging to macrohaplogroup M in different regions of Eurasia and Australasia.

Results

The macrohaplogroup M has a historical implantation in West Eurasia, including the Arabian Peninsula. Founder ages of M lineages in India are significantly younger than those in East Asia, Southeast Asia and Near Oceania. Moreover, there is a significant positive correlation between the age of the M haplogroups and its longitudinal geographical distribution. These results point to a colonization of the Indian subcontinent by modern humans carrying M lineages from the east instead the west side.

Conclusions

The existence of a northern route, previously proposed for the mtDNA macrohaplogroup N, is confirmed here for the macrohaplogroup M. Both mtDNA macrolineages seem to have differentiated in South East Asia from ancestral L3 lineages. Taking this genetic evidence and those reported by other disciplines we have constructed a new and more conciliatory model to explain the history of modern humans out of Africa.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-016-0816-8) contains supplementary material, which is available to authorized users.

Carriers of Mitochondrial DNA Macrohaplogroup N Lineages Reached Australia around 50,000 Years Ago following a Northern Asian Route

Background

The modern human colonization of Eurasia and Australia is mostly explained by a single-out-of-Africa exit following a southern coastal route throughout Arabia and India. However, dispersal across the Levant would better explain the introgression with Neanderthals, and more than one exit would fit better with the different ancient genomic components discovered in indigenous Australians and in ancient Europeans. The existence of an additional Northern route used by modern humans to reach Australia was previously deduced from the phylogeography of mtDNA macrohaplogroup N. Here, we present new mtDNA data and new multidisciplinary information that add more support to this northern route.

Methods

MtDNA hypervariable segments and haplogroup diagnostic coding positions were analyzed in 2,278 Saudi Arabs, from which 1,725 are new samples. Besides, we used 623 published mtDNA genomes belonging to macrohaplogroup N, but not R, to build updated phylogenetic trees to calculate their coalescence ages, and more than 70,000 partial mtDNA sequences were screened to establish their respective geographic ranges.

Results

The Saudi mtDNA profile confirms the absence of autochthonous mtDNA lineages in Arabia with coalescence ages deep enough to support population continuity in the region since the out-of-Africa episode. In contrast to Australia, where N(xR) haplogroups are found in high frequency and with deep coalescence ages, there are not autochthonous N(xR) lineages in India nor N(xR) branches with coalescence ages as deep as those found in Australia. These patterns are at odds with the supposition that Australian colonizers harboring N(xR) lineages used a route involving India as a stage. The most ancient N(xR) lineages in Eurasia are found in China, and inconsistently with the coastal route, N(xR) haplogroups with the southernmost geographical range have all more recent radiations than the Australians.

Conclusions

Apart from a single migration event via a southern route, phylogeny and phylogeography of N(xR) lineages support that people carrying mtDNA N lineages could have reach Australia following a northern route through Asia. Data from other disciplines also support this scenario.

Human settlement history between Sunda and Sahul: a focus on East Timor (Timor-Leste) and the Pleistocenic mtDNA diversity

BACKGROUND

Distinct, partly competing, "waves" have been proposed to explain human migration in(to) today's Island Southeast Asia and Australia based on genetic (and other) evidence. The paucity of high quality and high resolution data has impeded insights so far. In this study, one of the first in a forensic environment, we used the Ion Torrent Personal Genome Machine (PGM) for generating complete mitogenome sequences via stand-alone massively parallel sequencing and describe a standard data validation practice.

RESULTS

In this first representative investigation on the mitochondrial DNA (mtDNA) variation of East Timor (Timor-Leste) population including >300 individuals, we put special emphasis on the reconstruction of the initial settlement, in particular on the previously poorly resolved haplogroup P1, an indigenous lineage of the Southwest Pacific region. Our results suggest a colonization of southern Sahul (Australia) >37 kya, limited subsequent exchange, and a parallel incubation of initial settlers in northern Sahul (New Guinea) followed by westward migrations <28 kya.

CONCLUSIONS

The temporal proximity and possible coincidence of these latter dispersals, which encompassed autochthonous haplogroups, with the postulated "later" events of (South) East Asian origin pinpoints a highly dynamic migratory phase.

An expanded taxonomy of hepatitis C virus genotype 6: Characterization of 22 new full-length viral genomes

We characterized the full-length genomes of 22 hepatitis C virus genotype 6 (HCV-6) isolates: 10 from Vietnam (classified into subtypes 6e, 6h, 6p, 6r, 6s, and 6u), one from China (confirmed as a new subtype 6xd), and 11 from the Lao PDR (representing a new subtype 6xe plus eight novel variants). With these 22 new genomes, HCV-6 now has a diverse and extended taxonomic structure, comprised of 28 assigned subtypes (denoted 6a-6xe) and 27 unassigned lineages, all of which have been represented by full-length genomes. Our phylogenetic analyses also included many partially-sequenced novel variants of HCV-6 from Lao PDR. This revealed that Lao HCV isolates are genetically very diverse and are phylogenetically distributed in multiple lineages within genotype 6. Our results suggest that HCV-6 has been maintained in Laos, a landlocked country, since the common ancestor of genotype 6 and indicates historical dispersal of HCV-6 across Southeast Asia.

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We characterized 22 full-length genomes of HCV-6.

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They confirmed two new subtypes 6xd and 6xe plus eight novel variants.

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We also reanalyzed many partially-sequenced novel HCV-6 variants from Lao PDR.

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They are phylogenetically distributed across the whole of genotype 6.

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They indicate historical dispersal of HCV-6 across Southeast Asia.

Conservation in China of a novel group of HCV variants dating to six centuries ago

We characterized a novel group of HCV variants that are genetically related but distinct from each other belonging to genotype 6 (HCV-6). From 26 infected Austronesian-descended aborigines on Hainan Island, China, HCV sequences were determined followed by genetic analyses. Six nearly full-length genomes and 20 E1 sequences of HCV were obtained, which differ from each other and from all known HCV lineages by nucleotides above the intra-subtype level of 13%. Together with subtypes 6g and 6w, they constitute a phylogenetic group sharing a common ancestor dating from the end of the 12th century.

CONCLUSION

Our data indicate the maintenance of an isolated HCV-6 indigenous circulation on Hainan Island at least for six centuries.

Paternal and maternal genetic analysis of a desert Keriyan population: Keriyans are not the descendants of Guge Tibetans

The Keriyan people live in an isolated village in the Taklimakan Desert in Xinjiang, Western China. The origin and migration of the Keriyans remains unclear. We studied paternal and maternal genetic variance through typing Y-STR loci and sequencing the complete control region of the mtDNA and compared them with other adjacent populations. Data show that the Keriyan have relatively low genetic diversity on both the paternal and maternal lineages and possess both European and Asian specific haplogroups, indicating Keriyan is an admixture population of West and East. There is a gender-bias in the extent of contribution from Europe vs. Asia to the Keriyan gene pool. Keriyans have more genetic affinity to Uyghurs than to Tibetans. The Keriyan are not the descendants of the Guge Tibetans.

Patterns of human oral yeast species distribution on Hainan Island in China

Infections by yeast strains of the genus Candida are among the most prevalent fungal infections of humans. These yeasts are common residents of the oral mucosa and other body surfaces. Since most yeast infections are due to endogenous strains and that species of Candida differ in virulence properties and in intrinsic susceptibilities to antifungal drugs, understanding the human commensal yeast flora can help designing effective treatment and prevention strategies against yeast infections. Here, we report the patterns of yeast species distributions in the oral cavities of 1,799 people from Hainan Island in southern China. Based on sequence information at the fungal barcode locus ITS regions, 368 of the 415 obtained oral yeast strains were identified as belonging to 26 yeast species, while the remaining 47 strains all showed significant sequence divergence to the currently described species. The four most common yeast species were C. albicans (42 %), C. tropicalis (20 %), C. glabrata (5.5 %), and C. parapsilosis (4.1 %) and 10 of the 26 yeast species were represented by only one strain each. Our analyses identified that the gender of hosts and ethnical background showed no contribution to oral yeast species distributions. However, the health status, place of birth, current residency, and the age of hosts all showed significant contributions to the distributions of the four dominant yeast species. We compared our results with those reported previously and discussed the potential mechanisms for the observed differences in oral yeast species distributions.

[The research progress of human genetic diversity in China]

Human genetic diversity refers to genomic variation among races, ethnic groups, isolated populations and individuals worldwide, and is one major resource and tool on discovering human evolution and migration, interaction between genetic background and environment, and factors associated with human diseases and health. China has abundant and valuable resource of human genetic diversity due to 56 ethnic groups and a large population accounting for one fifth of the total population in the world. After decades of efforts, a large number of research data on human genetic diversity have been accumulated in China, and some of outcomes reach advanced international level. This review mainly focuses on the recent progress and outcomes achieved in applying genetic markers including morphological markers, biochemical and immunological markers and DNA markers in research of genetic diversity, and the application of mitochondrial DNA, Y chromosomal DNA, HLA and others in research of the origin and relationship of Chinese ethic groups, and the origin and mi-of modern East Asian populations. This review also summarizes the advances in the research fields of preservation and utilization of Chinese genetic resource, identification of genes associated with disease selective and adaptive for natural pressure, application of whole genome association study and next generation sequencing, and Chinese human genome as well.

Major population expansion of East Asians began before neolithic time: evidence of mtDNA genomes

It is a major question in archaeology and anthropology whether human populations started to grow primarily after the advent of agriculture, i.e., the Neolithic time, especially in East Asia, which was one of the centers of ancient agricultural civilization. To answer this question requires an accurate estimation of the time of lineage expansion as well as that of population expansion in a population sample without ascertainment bias. In this study, we analyzed all available mtDNA genomes of East Asians ascertained by random sampling, a total of 367 complete mtDNA sequences generated by the 1000 Genome Project, including 249 Chinese (CHB, CHD, and CHS) and 118 Japanese (JPT). We found that major mtDNA lineages underwent expansions, all of which, except for two JPT-specific lineages, including D4, D4b2b, D4a, D4j, D5a2a, A, N9a, F1a1'4, F2, B4, B4a, G2a1 and M7b1'2'4, occurred before 10 kya, i.e., before the Neolithic time (symbolized by Dadiwan Culture at 7.9 kya) in East Asia. Consistent to this observation, the further analysis showed that the population expansion in East Asia started at 13 kya and lasted until 4 kya. The results suggest that the population growth in East Asia constituted a need for the introduction of agriculture and might be one of the driving forces that led to the further development of agriculture.