Biology subjects

Stoneking, M.

Publications and source records attributed to Stoneking, M..

9 recordsLinked to original sources

bioRxiv2018

The role of matrilineality in shaping patterns of Y chromosome and mtDNA sequence variation in southwestern Angola

Southwestern Angola is a region characterized by contact between indigenous foragers and incoming food-producers, involving genetic and cultural exchanges between peoples speaking Kxa, Khoe-Kwadi and Bantu languages. Although present-day Bantu-speakers share a patrilocal residence pattern and matrilineal principle of clan and group membership, a highly stratified social setting divides dominant pastoralists from marginalized groups that subsist on alternative strategies and have previously been though to have pre-Bantu origins. Here, we compare new high-resolution sequence data from 2.3 Mb of the non-recombining Y chromosome (NRY) from 170 individuals with previously reported mitochondrial genomes (mtDNA), to investigate the population history of seven representative southwestern Angolan groups (Himba, Kuvale, Kwisi, Kwepe, Twa, Tjimba, !Xun) and to study the causes and consequences of sex-biased processes in their genetic variation. We found no clear link between the formerly Kwadi-speaking Kwepe and pre-Bantu eastern African migrants, and no pre-Bantu NRY lineages among Bantu-speaking groups, except for small amounts of \"Khoisan\" introgression. We therefore propose that irrespective of their subsistence strategies, all Bantu-speaking groups of the area share a male Bantu origin. Additionally, we show that in Bantu-speaking groups, the levels of among-group and between-group variation are higher for mtDNA than for NRY. These results, together with our previous demonstration that the matriclanic systems of southwestern Angolan Bantu groups are genealogically consistent, suggest that matrilineality strongly enhances both female population sizes and interpopulation mtDNA variation.

genetics↗

bioRxiv2018

Cultural Innovations influence patterns of genetic diversity in Northwestern Amazonia

Human populations often exhibit contrasting patterns of genetic diversity in the mtDNA and the non-recombining portion of the Y-chromosome (NRY), which reflect sex-specific cultural behaviors and population histories. Here, we sequenced 2.3 Mb of the NRY from 284 individuals representing more than 30 Native-American groups from Northwestern Amazonia (NWA) and compared these data to previously generated mtDNA genomes from the same groups, to investigate the impact of cultural practices on genetic diversity and gain new insights about NWA population history. Relevant cultural practices in NWA include postmarital residential rules and linguistic-exogamy, a marital practice in which men are required to marry women speaking a different language.\n\nWe identified 2,969 SNPs in the NRY sequences; only 925 SNPs were previously described. The NRY and mtDNA data showed that males and females experienced different demographic histories: the female effective population size has been larger than that of males through time, and both markers show an increase in lineage diversification beginning ~5,000 years ago, with a male-specific expansion occurring ~3,500 years ago. These dates are too recent to be associated with agriculture, therefore we propose that they reflect technological innovations and the expansion of regional trade networks documented in the archaeological evidence. Furthermore, our study provides evidence of the impact of postmarital residence rules and linguistic exogamy on genetic diversity patterns. Finally, we highlight the importance of analyzing high-resolution mtDNA and NRY sequences to reconstruct demographic history, since this can differ considerably between males and females.

genetics↗

bioRxiv2017

Genetic structure and sex-biased gene flow in the history of southern African populations

ObjectivesWe investigated the genetic history of southern African populations with a special focus on their paternal history. We reexamined previous claims that the Y-chromosome haplogroup E1b1b was brought to southern Africa by pastoralists from eastern Africa, and investigated patterns of sex-biased gene flow in southern Africa.\n\nMaterial and MethodsWe analyzed previously published complete mtDNA genome sequences and ~900 kb of NRY sequences from 23 populations from Namibia, Botswana and Zambia, as well as haplogroup frequencies from a large sample of southern African populations and 23 newly genotyped Y-linked STR loci for samples assigned to haplogroup E1b1b.\n\nResultsOur results support an eastern African origin for Y-chromosome haplogroup E1b1b; however, its current distribution in southern Africa is not strongly associated with pastoralism, suggesting a more complex origin for pastoralism in this region. We confirm that the Bantu expansion had a notable genetic impact in southern Africa, and that in this region it was probably a rapid, male-dominated expansion. Furthermore, we find a significant increase in the intensity of sex-biased gene flow from north to south, which may reflect changes in the social dynamics between Khoisan and Bantu groups over time.\n\nConclusionsOur study shows that the population history of southern Africa has been very complex, with different immigrating groups mixing to different degrees with the autochthonous populations. The Bantu expansion led to heavily sex-biased admixture as a result of interactions between Khoisan females and Bantu males, with a geographic gradient which may reflect changes in the social dynamics between Khoisan and Bantu groups over time.

genetics↗

bioRxiv2017

Contrasting maternal and paternal genetic variation of hunter-gatherer groups in Thailand

The Maniq and Mlabri are the only recorded nomadic hunter-gatherer groups in Thailand. Here, we sequenced complete mitochondrial (mt) DNA genomes and ~2.364 Mbp of non- recombining Y chromosome (NRY) to learn more about the origins of these two enigmatic populations. Both groups exhibited low genetic diversity compared to other Thai populations, and contrasting patterns of mtDNA and NRY diversity: there was greater mtDNA diversity in the Maniq than in the Mlabri, while the converse was true for the NRY. We found basal uniparental lineages in the Maniq, namely mtDNA haplogroups M21a, R21 and M17a, and NRY haplogroup K. Overall, the Maniq are genetically similar to other negrito groups in Southeast Asia. By contrast, the Mlabri haplogroups (B5a1b1 for mtDNA and O1b1a1a1b and O1b1a1a1b1a1 for the NRY) are common lineages in Southeast Asian non-negrito groups, and overall the Mlabri are genetically similar to their linguistic relatives (Htin and Khmu) and other groups from northeastern Thailand. In agreement with previous studies of the Mlabri, our results indicate that the Malbri do not directly descend from the indigenous negritos. Instead, they likely have a recent origin (within the past 1,000 years) by an extreme founder event (involving just one maternal and two paternal lineages) from an agricultural group, most likely the Htin or a closely- related group.

genetics↗

bioRxiv2017

The gateway into Remote Oceania: new insights from genome-wide data

A widely accepted two-wave scenario of human settlement of Oceania involves the first out-of-Africa migration ca 50,000 ya, and one of the most geographically-widespread dispersals of people, known as the Austronesian expansion, which reached the Bismarck Archipelago by about 3,450 ya. While earlier genetic studies provided evidence for extensive sex-biased admixture between the incoming and the indigenous populations, some archaeological, linguistic and genetic evidence indicates a more complicated picture of settlement. To study regional variation in Oceania in more detail, we have compiled a genome-wide dataset of 823 individuals from 72 populations (including 50 populations from Oceania) and over 620,000 autosomal SNPs. We show that the initial dispersal of people from the Bismarck Archipelago into Remote Oceania occurred in a \"leapfrog\" fashion, completely by-passing the main chain of the Solomon Islands, and that the colonization of the Solomon Islands proceeded in a bi-directional manner. Our results also support a divergence between western and eastern Solomons, in agreement with the sharp linguistic divide known as the Tryon-Hackman line. We also report substantial post-Austronesian gene flow across the Solomons. In particular, Santa Cruz (in Remote Oceania) exhibits extraordinarily high levels of Papuan ancestry that cannot be explained by a simple bottleneck/founder event scenario. Finally, we use simulations to show that discrepancies between different methods for dating admixture likely reflect different sensitivities of the methods to multiple admixture events from the same (or similar) sources. Overall, this study points to the importance of fine-scale sampling to understand the complexities of human population history.

evolutionary biology↗

bioRxiv2017

New insights from Thailand into the maternal genetic history of Mainland Southeast Asia

Tai-Kadai (TK) is one of the major language families in Mainland Southeast Asia (MSEA), with a concentration in the area of Thailand and Laos. Our previous study of 1,234 mtDNA genome sequences supported a demic diffusion scenario in the spread of TK languages from southern China to Laos as well as northern and northeastern Thailand. Here we add an additional 560 mtDNA sequences from 22 groups, with a focus on the TK-speaking central Thai people and the Sino-Tibetan speaking Karen. We find extensive diversity, including 62 haplogroups not reported previously from this region. Demic diffusion is still a preferable scenario for central Thais, emphasizing the extension and expansion of TK people through MSEA, although there is also some support for an admixture model. We also tested competing models concerning the genetic relationships of groups from the major MSEA languages, and found support for an ancestral relationship of TK and Austronesian-speaking groups.

genetics↗

bioRxiv2017

The maternal genetic history of the Angolan Namib Desert: a key region for understanding the peopling of southern Africa

Southern Angola is a poorly studied region, inhabited by populations that have been associated with different migratory movements into southern Africa. Besides the long-standing presence of indigenous Kxa-speaking foragers and the more recent arrival of Bantu-speaking pastoralists, ethnographic and linguistic studies have suggested that other pre-Bantu communities were also present in the Namib desert, including peripatetic groups like the Kwepe (formerly Kwadi speakers), Twa and Kwisi. Here we evaluate previous peopling hypotheses by analyzing the relationships between seven groups from the Namib desert (Kuvale, Himba, Tjimba, Kwisi, Twa, Kwepe) and Kunene Province (!Xun), based on newly collected linguistic data and 295 complete mtDNA genomes. We found that: i) all groups from the Namib desert have genealogically-consistent matriclanic systems that had a strong impact on their maternal genetic structure by enhancing genetic drift and population differentiation; ii) the dominant pastoral groups represented by the Kuvale and Himba were part of a Bantu proto-population that also included the ancestors of present-day Damara and Herero peoples from Namibia; iii) Tjimba are closely related to the Himba; iv) the Kwepe, Twa and Kwisi have a divergent Bantu-related mtDNA profile and probably stem from a single population that does not show clear signs of being a pre-Bantu indigenous group. Taken together, our results suggest that the maternal genetic structure of the different groups from the Namib desert is largely derived from endogamous Bantu peoples, and that their social stratification and different subsistence patterns are not indicative of remnant groups, but reflect Bantu-internal variation and ethnogenesis.

genetics↗

bioRxiv2017

High Resolution Mitochondrial DNA Analysis Sheds Light On Human Diversity, Cultural Interactions And Population Mobility In Northwestern Amazonia

ObjectivesNorthwestern Amazonia (NWA) is a center of high linguistic and cultural diversity. Several language families and linguistic isolates occur in this region, as well as different subsistence patterns: some groups are foragers while others are agriculturalists. In addition, speakers of Eastern Tukanoan languages are known for practicing linguistic exogamy, a marriage system in which partners must come from different language groups. In this study, we use high resolution mitochondrial DNA sequencing to investigate the impact of this linguistic and cultural diversity on the genetic relationships and structure of NWA groups.\n\nMethodsWe collected saliva samples from individuals representing 40 different NWA ethnolinguistic groups and sequenced 439 complete mitochondrial genomes to an average coverage of 1030x.\n\nResultsThe mtDNA data revealed that NWA populations have high genetic diversity with extensive sharing of haplotypes among groups. Moreover, groups who practice linguistic exogamy have higher mtDNA diversity, while the foraging Nukak have lower diversity. We also find that rivers play a more important role than either geography or language affiliation in structuring the genetic relationships of populations.\n\nDiscussionContrary to the view of NWA as a pristine area inhabited by small human populations living in isolation, our data support a view of high diversity and contact among different ethnolinguistic groups; movement along rivers has probably facilitated this contact. Additionally, we provide evidence for the impact of cultural practices, such as linguistic exogamy, on patterns of genetic variation. Overall, this study provides new data and insights into a remote and little-studied region of the world.

evolutionary biology↗

bioRxiv2017

Mitochondrial DNA heteroplasmy is shared between human liver lobes

Mitochondrial DNA (mtDNA) heteroplasmy (intra-individual variation) varies among different human tissues and increases with age, suggesting that the majority of mtDNA heteroplasmies are acquired, rather than inherited. However, the extent to which heteroplasmic sites are shared across a tissue remains an open question. We therefore investigated heteroplasmy in two liver samples (one from each primary lobe) from 83 Europeans, sampled at autopsy. Minor allele frequencies (MAF) at heteroplasmic sites were significantly correlated between the two liver samples from an individual, with significantly more sharing of heteroplasmic sites in the control region than in the coding region. We show that this increased sharing for the control region cannot be explained by recent mutations at just a few specific heteroplasmic sites or by the possible presence of 7S DNA. Moreover, we carried out simulations to show that there is significantly more sharing than would be predicted from random genetic drift from a common progenitor cell. We also observe a significant excess of non-synonymous vs. synonymous heteroplasmies in the coding region, but significantly more sharing of synonymous heteroplasmies. These contrasting patterns for the control vs. the coding region, and for non-synonymous vs. synonymous heteroplasmies, suggest that selection plays a role in heteroplasmy sharing.

genetics↗