Analysis of the human Y-chromosome haplogroup Q characterizes ancient population movements in Eurasia and the Americas

Background: Recent genome studies of modern and ancient samples have proposed that Native Americans derive from a subset of the Eurasian gene pool carried to America by an ancestral Beringian population, from which two well-differentiated components originated and subsequently mixed in different proportion during their spread in the Americas. To assess the timing, places of origin and extent of admixture between these components, we performed an analysis of the Y-chromosome haplogroup Q, which is the only Pan-American haplogroup and accounts for virtually all Native American Y chromosomes in Mesoamerica and South America. Results: Our analyses of 1.5 Mb of 152 Y chromosomes, 34 re-sequenced in this work, support a "coastal and inland routes scenario" for the first entrance of modern humans in North America. We show a major phase of male population growth in the Americas after 15 thousand years ago (kya), followed by a period of constant population size from 8 to 3 kya, after which a secondary sign of growth was registered. The estimated dates of the first expansion in Mesoamerica and the Isthmo-Colombian Area, mainly revealed by haplogroup Q-Z780, suggest an entrance in South America prior to 15 kya. During the global constant population size phase, local South American hints of growth were registered by different Q-M848 sub-clades. These expansion events, which started during the Holocene with the improvement of climatic conditions, can be ascribed to multiple cultural changes rather than a steady population growth and a single cohesive culture diffusion as it occurred in Europe. Conclusions: We established and dated a detailed haplogroup Q phylogeny that provides new insights into the geographic distribution of its Eurasian and American branches in modern and ancient samples

Y-Chromosome Diversity in Modern Bulgarians: New Clues about Their Ancestry

To better define the structure and origin of the Bulgarian paternal gene pool, we have examined the Y-chromosome variation in 808 Bulgarian males. The analysis was performed by high-resolution genotyping of biallelic markers and by analyzing the STR variation within the most informative haplogroups. We found that the Y-chromosome gene pool in modern Bulgarians is primarily represented by Western Eurasian haplogroups with , 40% belonging to haplogroups E-V13 and I-M423, and 20% to R-M17. Haplogroups common in the Middle East (J and G) and in South Western Asia (R-L23*) occur at frequencies of 19% and 5%, respectively. Haplogroups C, N and Q, distinctive for Altaic and Central Asian Turkic-speaking populations, occur at the negligible frequency of only 1.5%. Principal Component analyses group Bulgarians with European populations, apart from Central Asian Turkic-speaking groups and South Western Asia populations. Within the country, the genetic variation is structured in Western, Central and Eastern Bulgaria indicating that the Balkan Mountains have been permeable to human movements. The lineage analysis provided the following interesting results: (i) R-L23* is present in Eastern Bulgaria since the post glacial period; (ii) haplogroup E-V13 has a Mesolithic age in Bulgaria from where it expanded after the arrival of farming; (iii) haplogroup J-M241 probably reflects the Neolithic westward expansion of farmers from the earliest sites along the Black Sea. On the whole, in light of the most recent historical studies, which indicate a substantial proto-Bulgarian input to the contemporary Bulgarian people, our data suggest that a common paternal ancestry between the proto-Bulgarians and the Altaic and Central Asian Turkic-speaking populations either did not exist or was negligible

Phylogeography of human Y-chromosome haplogroup Q3-L275 from an academic/ citizen science collaboration

Background: The Y-chromosome haplogroup Q has three major branches: Q1, Q2, and Q3. Q1 is found in both Asia and the Americas where it accounts for about 90% of indigenous Native American Y-chromosomes; Q2 is found in North and Central Asia; but little is known about the third branch, Q3, also named Q1b-L275. Here, we combined the efforts of population geneticists and genetic genealogists to use the potential of full Y-chromosome sequencing for reconstructing haplogroup Q3 phylogeography and suggest possible linkages to events in population history. Results: We analyzed 47 fully sequenced Y-chromosomes and reconstructed the haplogroup Q3 phylogenetic tree in detail. Haplogroup Q3-L275, derived from the oldest known split within Eurasian/American haplogroup Q, most likely occurred in West or Central Asia in the Upper Paleolithic period. During the Mesolithic and Neolithic epochs, Q3 remained a minor component of the West Asian Y-chromosome pool and gave rise to five branches (Q3a to Q3e), which spread across West, Central and parts of South Asia. Around 3–4 millennia ago (Bronze Age), the Q3a branch underwent a rapid expansion, splitting into seven branches, some of which entered Europe. One of these branches, Q3a1, was acquired by a population ancestral to Ashkenazi Jews and grew within this population during the 1st millennium AD, reaching up to 5% in present day Ashkenazi. Conclusions: This study dataset was generated by a massive Y-chromosome genotyping effort in the genetic genealogy community, and phylogeographic patterns were revealed by a collaboration of population geneticists and genetic genealogists. This positive experience of collaboration between academic and citizen science provides a model for further joint projects. Merging data and skills of academic and citizen science promises to combine, respectively, quality and quantity, generalization and specialization, and achieve a well-balanced and careful interpretation of the paternal-side history of human populations

A társadalmak környezeti sebezhetősége, ellenálló- és alkalmazkodó képessége:a korai történelmi példáktól a sérülékenység globalizációjáig (Environmental vulnerability, resilience and adaptation capacities of societies: their historical examples and globalization)

Detailed phylogenetic tree of the haplogroup Q3-L275. 47 Q3-L275 samples and 1 Q1a-M346 outgroup. Constructed with the Phylomurka software using MP criteria, from the alignment obtained with read depth > = 2, base quality > = 15 and mapping quality > = 10, call rate = 60%. (XLSX 279 kb

Ancient Migratory Events in the Middle East: New Clues from the Y-Chromosome Variation of Modern Iranians

Knowledge of high resolution Y-chromosome haplogroup diversification within Iran provides important geographic context regarding the spread and compartmentalization of male lineages in the Middle East and southwestern Asia. At present, the Iranian population is characterized by an extraordinary mix of different ethnic groups speaking a variety of Indo-Iranian, Semitic and Turkic languages. Despite these features, only few studies have investigated the multiethnic components of the Iranian gene pool. In this survey 938 Iranian male DNAs belonging to 15 ethnic groups from 14 Iranian provinces were analyzed for 84 Y-chromosome biallelic markers and 10 STRs. The results show an autochthonous but non-homogeneous ancient background mainly composed by J2a sub-clades with different external contributions. The phylogeography of the main haplogroups allowed identifying post-glacial and Neolithic expansions toward western Eurasia but also recent movements towards the Iranian region from western Eurasia (R1b-L23), Central Asia (Q-M25), Asia Minor (J2a-M92) and southern Mesopotamia (J1-Page08). In spite of the presence of important geographic barriers (Zagros and Alborz mountain ranges, and the Dasht-e Kavir and Dash-e Lut deserts) which may have limited gene flow, AMOVA analysis revealed that language, in addition to geography, has played an important role in shaping the nowadays Iranian gene pool. Overall, this study provides a portrait of the Y-chromosomal variation in Iran, useful for depicting a more comprehensive history of the peoples of this area as well as for reconstructing ancient migration routes. In addition, our results evidence the important role of the Iranian plateau as source and recipient of gene flow between culturally and genetically distinct population

Mitochondrial DNA Backgrounds Might Modulate Diabetes Complications Rather than T2DM as a Whole

Mitochondrial dysfunction has been implicated in rare and common forms of type 2 diabetes (T2DM). Additionally, rare mitochondrial DNA (mtDNA) mutations have been shown to be causal for T2DM pathogenesis. So far, many studies have investigated the possibility that mtDNA variation might affect the risk of T2DM, however, when found, haplogroup association has been rarely replicated, even in related populations, possibly due to an inadequate level of haplogroup resolution. Effects of mtDNA variation on diabetes complications have also been proposed. However, additional studies evaluating the mitochondrial role on both T2DM and related complications are badly needed. To test the hypothesis of a mitochondrial genome effect on diabetes and its complications, we genotyped the mtDNAs of 466 T2DM patients and 438 controls from a regional population of central Italy (Marche). Based on the most updated mtDNA phylogeny, all 904 samples were classified into 57 different mitochondrial sub-haplogroups, thus reaching an unprecedented level of resolution. We then evaluated whether the susceptibility of developing T2DM or its complications differed among the identified haplogroups, considering also the potential effects of phenotypical and clinical variables. MtDNA backgrounds, even when based on a refined haplogroup classification, do not appear to play a role in developing T2DM despite a possible protective effect for the common European haplogroup H1, which harbors the G3010A transition in the MTRNR2 gene. In contrast, our data indicate that different mitochondrial haplogroups are significantly associated with an increased risk of specific diabetes complications: H (the most frequent European haplogroup) with retinopathy, H3 with neuropathy, U3 with nephropathy, and V with renal failure

In search of the genetic footprints of Sumerians: a survey of Y-chromosome and mtDNA variation in the Marsh Arabs of Iraq

Background For millennia, the southern part of the Mesopotamia has been a wetland region generated by the Tigris and Euphrates rivers before flowing into the Gulf. This area has been occupied by human communities since ancient times and the present-day inhabitants, the Marsh Arabs, are considered the population with the strongest link to ancient Sumerians. Popular tradition, however, considers the Marsh Arabs as a foreign group, of unknown origin, which arrived in the marshlands when the rearing of water buffalo was introduced to the region. Results To shed some light on the paternal and maternal origin of this population, Y chromosome and mitochondrial DNA (mtDNA) variation was surveyed in 143 Marsh Arabs and in a large sample of Iraqi controls. Analyses of the haplogroups and sub-haplogroups observed in the Marsh Arabs revealed a prevalent autochthonous Middle Eastern component for both male and female gene pools, with weak South-West Asian and African contributions, more evident in mtDNA. A higher male than female homogeneity is characteristic of the Marsh Arab gene pool, likely due to a strong male genetic drift determined by socio-cultural factors (patrilocality, polygamy, unequal male and female migration rates). Conclusions Evidence of genetic stratification ascribable to the Sumerian development was provided by the Y-chromosome data where the J1-Page08 branch reveals a local expansion, almost contemporary with the Sumerian City State period that characterized Southern Mesopotamia. On the other hand, a more ancient background shared with Northern Mesopotamia is revealed by the less represented Y-chromosome lineage J1-M267*. Overall our results indicate that the introduction of water buffalo breeding and rice farming, most likely from the Indian sub-continent, only marginally affected the gene pool of autochthonous people of the region. Furthermore, a prevalent Middle Eastern ancestry of the modern population of the marshes of southern Iraq implies that if the Marsh Arabs are descendants of the ancient Sumerians, also the Sumerians were most likely autochthonous and not of Indian or South Asian ancestry

The use of surname and Y-chromocome analyses for reconstructing past population structures: the test case of Sardinia

The male specific region of the Y chromosome is uniparentally transmitted. It escapes recombination and its evolution is only due to the sequential accumulation of new mutations along radiating paternal lineages. Due to this process, which occurred mainly during and after the process of human colonization and diffusion into the different geographic region, the present Y-chromosome sequence variation represents a unique record of the biological history of our species and modern populations. Its analysis allows the identification of ancestral and founder haplotypes, the detection of ancient migration routes and the estimation of migration times. However, this analysis is sometimes undermined by recent migrations which became more and more important also for “isolated” populations, weakening the boundaries of genetic isolates by making uniform the distribution of genetic markers. A solution for this problem is represented by the reconstruction of the ancient isolates starting from the present data by using the information obtained from the surname analysis. With the aim of investigating the peopling of Sardinia and the aspects of its human Y-chromosome contemporary variation that can be ascribed to primary colonization, Neolithic dispersals or more recent events of gene flow, we have analyzed in detail the Y chromosome haplogroup distributions in a wide sample (more than 500 Y chromosomes) whose surname origin could be attributed specifically to one of the different Sardinian linguistic zones (Contini et al., 1989, Piazza et al. 1987). In addition, in order to evaluate the divergence of the different haplogroups observed in the island, and therefore their coalescent time, a set of 12 STR loci was examined. On the whole, by the comparison of 11 regions representative of ancient Sardinian isolates, a significant differentiation has been confirmed for the central eastern area of the island, in agreement with historical and linguistic data that indicate this region as the “archaic”zone. This is due to a lower incidence of haplogroups arrived in Europe during the Neolithic and post Neolithic times (Cruciani et al. 2004, Semino et et al. 2004), but mainly to a significative higher frequency of the Paleolithic haplogroup I-M26

Reconstructing the genetic history of Italians: new insights from a male (Y-chromosome) perspective.

BACKGROUND: Due to its central and strategic position in Europe and in the Mediterranean Basin, the Italian Peninsula played a pivotal role in the first peopling of the European continent and has been a crossroad of peoples and cultures since then. AIM: This study aims to gain more information on the genetic structure of modern Italian populations and to shed light on the migration/expansion events that led to their formation. SUBJECTS AND METHODS: High resolution Y-chromosome variation analysis in 817 unrelated males from 10 informative areas of Italy was performed. Haplogroup frequencies and microsatellite haplotypes were used, together with available data from the literature, to evaluate Mediterranean and European inputs and date their arrivals. RESULTS: Fifty-three distinct Y-chromosome lineages were identified. Their distribution is in general agreement with geography, southern populations being more differentiated than northern ones. CONCLUSIONS: A complex genetic structure reflecting the multifaceted peopling pattern of the Peninsula emerged: southern populations show high similarity with those from the Middle East and Southern Balkans, while those from Northern Italy are close to populations of North-Western Europe and the Northern Balkans. Interestingly, the population of Volterra, an ancient town of Etruscan origin in Tuscany, displays a unique Y-chromosomal genetic structure