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Post by djoser-xyyman on Apr 19, 2010 12:59:29 GMT -5
This is one of the few studies that infer that MtDNA - N is African in Origin. Wasn't the neolithic farmers(female) N??
===== Whole-mtDNA genome sequence analysis of ancient African lineages. Gonder MK, Mortensen HM, Reed FA, de Sousa A, Tishkoff SA.
Department of Biology, University of Maryland, MD, USA.
Abstract Studies of human mitochondrial (mt) DNA genomes demonstrate that the root of the human phylogenetic tree occurs in Africa. Although 2 mtDNA lineages with an African origin (haplogroups M and N) were the progenitors of all non-African haplogroups, macrohaplogroup L (including haplogroups L0-L6) is limited to sub-Saharan Africa. Several L haplogroup lineages occur most frequently in eastern Africa (e.g., L0a, L0f, L5, and L3g), but some are specific to certain ethnic groups, such as haplogroup lineages L0d and L0k that previously have been found nearly exclusively among southern African "click" speakers. Few studies have included multiple mtDNA genome samples belonging to haplogroups that occur in eastern and southern Africa but are rare or absent elsewhere. This lack of sampling in eastern Africa makes it difficult to infer relationships among mtDNA haplogroups or to examine events that occurred early in human history. We sequenced 62 complete mtDNA genomes of ethnically diverse Tanzanians, southern African Khoisan speakers, and Bakola Pygmies and compared them with a global pool of 226 mtDNA genomes. From these, we infer phylogenetic relationships amongst mtDNA haplogroups and estimate the time to most recent common ancestor (TMRCA) for haplogroup lineages. These data suggest that Tanzanians have high genetic diversity and possess ancient mtDNA haplogroups, some of which are either rare (L0d and L5) or absent (L0f) in other regions of Africa. We propose that a large and diverse human population has persisted in eastern Africa and that eastern Africa may have been an ancient source of dispersion of modern humans both within and outside of Africa.
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Post by djoser-xyyman on Apr 19, 2010 13:02:27 GMT -5
mtDNA variation in the South African Kung and Khwe-and their genetic relationships to other African populations. Chen YS, Olckers A, Schurr TG, Kogelnik AM, Huoponen K, Wallace DC.
Center for Molecular Medicine, Emory University, Atlanta, GA, 30322, USA.
Abstract The mtDNA variation of 74 Khoisan-speaking individuals (Kung and Khwe) from Schmidtsdrift, in the Northern Cape Province of South Africa, was examined by high-resolution RFLP analysis and control region (CR) sequencing. The resulting data were combined with published RFLP haplotype and CR sequence data from sub-Saharan African populations and then were subjected to phylogenetic analysis to deduce the evolutionary relationships among them. More than 77% of the Kung and Khwe mtDNA samples were found to belong to the major mtDNA lineage, macrohaplogroup L* (defined by a HpaI site at nucleotide position 3592), which is prevalent in sub-Saharan African populations. Additional sets of RFLPs subdivided macrohaplogroup L* into two extended haplogroups-L1 and L2-both of which appeared in the Kung and Khwe. Besides revealing the significant substructure of macrohaplogroup L* in African populations, these data showed that the Biaka Pygmies have one of the most ancient RFLP sublineages observed in African mtDNA and, thus, that they could represent one of the oldest human populations. In addition, the Kung exhibited a set of related haplotypes that were positioned closest to the root of the human mtDNA phylogeny, suggesting that they, too, represent one of the most ancient African populations. Comparison of Kung and Khwe CR sequences with those from other African populations confirmed the genetic association of the Kung with other Khoisan-speaking peoples, whereas the Khwe were more closely linked to non-Khoisan-speaking (Bantu) populations. Finally, the overall sequence divergence of 214 African RFLP haplotypes defined in both this and an earlier study was 0.364%, giving an estimated age, for all African mtDNAs, of 125,500-165,500 years before the present, a date that is concordant with all previous estimates derived from mtDNA and other genetic data, for the time of origin of modern humans in Africa.
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Post by djoser-xyyman on Apr 19, 2010 13:08:05 GMT -5
Did the Bantu migration start 2000BC? And from North Central Africa??? Bantu . . .cattle herders???
==== On the edge of Bantu expansions: mtDNA, Y chromosome and lactase persistence genetic variation in southwestern Angola. Coelho M, Sequeira F, Luiselli D, Beleza S, Rocha J.
IPATIMUP, Instituto de Patologia e Imunologia Molecular da Universidade do Porto, R Dr Roberto Frias s/n, 4200-465 Porto, Portugal. mcoelho@ipatimup.pt
Abstract BACKGROUND: Current information about the expansion of Bantu-speaking peoples is hampered by the scarcity of genetic data from well identified populations from southern Africa. Here, we fill an important gap in the analysis of the western edge of the Bantu migrations by studying for the first time the patterns of Y-chromosome, mtDNA and lactase persistence genetic variation in four representative groups living around the Namib Desert in southwestern Angola (Ovimbundu, Ganguela, Nyaneka-Nkumbi and Kuvale). We assessed the differentiation between these populations and their levels of admixture with Khoe-San groups, and examined their relationship with other sub-Saharan populations. We further combined our dataset with previously published data on Y-chromosome and mtDNA variation to explore a general isolation with migration model and infer the demographic parameters underlying current genetic diversity in Bantu populations. RESULTS: Correspondence analysis, lineage sharing patterns and admixture estimates indicate that the gene pool from southwestern Angola is predominantly derived from West-Central Africa. The pastoralist Herero-speaking Kuvale people were additionally characterized by relatively high frequencies of Y-chromosome (12%) and mtDNA (22%) Khoe-San lineages, as well as by the presence of the -14010C lactase persistence mutation (6%), which likely originated in non-Bantu pastoralists from East Africa. Inferred demographic parameters show that both male and female populations underwent significant size growth after the split between the western and eastern branches of Bantu expansions occurring 4000 years ago. However, males had lower population sizes and migration rates than females throughout the Bantu dispersals. CONCLUSION: Genetic variation in southwestern Angola essentially results from the encounter of an offshoot of West-Central Africa with autochthonous Khoisan-speaking peoples from the south. Interactions between the Bantus and the Khoe-San likely involved cattle herders from the two groups sharing common aspects of their social organization. The presence of the -14010C mutation in southwestern Angola provides a link between the East and Southwest African pastoral scenes that might have been established indirectly, through migrations of Khoe herders across southern Africa. Differences in patterns of mtDNA and Y-chromosome intrapopulation diversity and interpopulation differentiation may be explained by contrasting demographic histories underlying the current female and male genetic variation.
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Post by djoser-xyyman on Apr 19, 2010 13:26:27 GMT -5
Craniometric variation, genetic theory, and modern human origins. Relethford JH, Harpending HC.
Department of Anthropology, State University of New York College at Oneonta 13820.
Abstract Recent controversies surrounding models of modern human origins have focused on among-group variation, particularly the reconstruction of phylogenetic trees from mitochondrial DNA (mtDNA) and the dating of population divergence. Problems in tree estimation have been seen as weakening the case for a replacement model and favoring a multiregional evolution model. There has been less discussion of patterns of within-group variation, although the mtDNA evidence has consistently shown the greatest diversity within African populations. Problems of interpretation abound given the numerous factors that can influence within-group variation, including the possibility of earlier divergence, differences in population size, patterns of population expansion, and variation in migration rates. We present a model of within-group phenotypic variation and apply it to a large set of craniometric data representing major Old World geographic regions (57 measurements for 1,159 cases in four regions: Europe, Sub-Saharan Africa, Australasia, and the Far East). The model predicts a linear relationship between variation within populations (the average within-group variance) and variation between populations (the genetic distance of populations to pooled phenotypic means). On a global level this relationship should hold if the long-term effective population sizes of each region are correctly specified. Other potential effects on within-group variation are accounted for by the model. Comparison of observed and expected variances under the assumption of equal effective sizes for four regions indicates significantly greater within-group variation in Africa and significantly less within-group variation in Europe. These results suggest that the long-term effective population size was greatest in Africa. Closer examination of the model suggests that the long-term African effective size was roughly three times that of any other geographic region. Using these estimates of relative population size, we present a method for analyzing ancient population structure, which provides estimates of ancient migration. This method allows us to reconstruct migration history between geographic regions after adjustment for the effect of genetic drift on interpopulational distances. Our results show a clear isolation of Africa from other regions. We then present a method that allows direct estimation of the ancient migration matrix, thus providing us with information on the actual extent of interregional migration. These methods also provide estimates of time frames necessary to reach genetic equilibrium. The ultimate goal is extracting as much information from present-day patterns of human variation relevant to issues of human origins.(ABSTRACT TRUNCATED AT 400 WORDS)
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Post by djoser-xyyman on Apr 19, 2010 14:57:31 GMT -5
==== Mitochondrial DNA geneflow indicates preferred usage of the Levant Corridor over the Horn of Africa passageway. Rowold DJ, Luis JR, Terreros MC, Herrera RJ.
Department of Biological Sciences, Florida International University, University Park, OE 304, Miami, FL 33199, USA.
Abstract Both the Levantine Corridor and the Horn of Africa route have figured prominently in early hominid migrations from Africa to Eurasia. To gauge the importance of these two African-Asian thoroughfares in the demic movements of modern man, we surveyed the mtDNA control region variation and coding polymorphisms of 739 individuals representing ten African and Middle Eastern populations. Two of these collections, Egypt and Yemen, are geographically close to the Levant and Horn of Africa, respectively. In this analysis, we uncover genetic evidence for the preferential use of the Levantine Corridor in the Upper Paleolithic to Neolithic dispersals of haplogroups H, J*, N1b, and T1, in contrast to an overwhelming preference in favor of the Horn of Africa for the intercontinental expansion of M1 during the Middle to Upper Paleolithic. Furthermore, we also observed a higher frequency of sub-Saharan mtDNA compared to NRY lineages in the Middle Eastern collections, a pattern also seen in previous studies. In short, the results of this study suggest that several migratory episodes of maternal lineages occurred across the African-Asian corridors since the first African exodus of modern Homo sapiens sapiens.
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Post by djoser-xyyman on Apr 20, 2010 8:03:34 GMT -5
The complex and diversified mitochondrial gene pool of Berber populations. Coudray C, Olivieri A, Achilli A, Pala M, Melhaoui M, Cherkaoui M, El-Chennawi F, Kossmann M, Torroni A, Dugoujon JM. Laboratoire d'Anthropobiologie, CNRS FRE2960, Université Paul Sabatier, 37 allées Jules Guesde, Toulouse, France. clotilde.coudray@wanadoo.fr Abstract The mitochondrial DNA variation of 295 Berber-speakers from Morocco (Asni, Bouhria and Figuig) and the Egyptian oasis of Siwa was evaluated by sequencing a portion of the control region (including HVS-I and part of HVS-II) and surveying haplogroup-specific coding region markers. Our findings show that the Berber mitochondrial pool is characterized by an overall high frequency of Western Eurasian haplogroups, a somehow lower frequency of sub-Saharan L lineages, and a significant (but differential) presence of North African haplogroups U6 and M1, thus occupying an intermediate position between European and sub-Saharan populations in PCA analysis. A clear and significant genetic differentiation between the Berbers from Maghreb and Egyptian Berbers was also observed. The first are related to European populations as shown by haplogroup H1 and V frequencies, whereas the latter share more affinities with East African and Nile Valley populations as indicated by the high frequency of M1 and the presence of L0a1, L3i, L4*, and L4b2 lineages. Moreover, haplogroup U6 was not observed in Siwa. We conclude that the origins and maternal diversity of Berber populations are old and complex, and these communities bear genetic characteristics resulting from various events of gene flow with surrounding and migrating populations.
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Post by djoser-xyyman on Apr 20, 2010 9:48:44 GMT -5
Here is something interesting.. ..
will try to post the entire study
==== 2002 May;70(5):1197-214. Epub 2002 Mar 21.
A back migration from Asia to sub-Saharan Africa is supported by high-resolution analysis of human Y-chromosome haplotypes. Cruciani F, Santolamazza P, Shen P, Macaulay V, Moral P, Olckers A, Modiano D, Holmes S, Destro-Bisol G, Coia V, Wallace DC, Oefner PJ, Torroni A, Cavalli-Sforza LL, Scozzari R, Underhill PA.
Dipartimenti di Genetica e Biologia Molecolare, Università La Sapienza, Rome, Italy. fulvio.cruciani@uniroma1.it
Abstract The variation of 77 biallelic sites located in the nonrecombining portion of the Y chromosome was examined in 608 male subjects from 22 African populations. This survey revealed a total of 37 binary haplotypes, which were combined with microsatellite polymorphism data to evaluate internal diversities and to estimate coalescence ages of the binary haplotypes. The majority of binary haplotypes showed a nonuniform distribution across the continent. Analysis of molecular variance detected a high level of interpopulation diversity (PhiST=0.342), which appears to be partially related to the geography (PhiCT=0.230). In sub-Saharan Africa, the recent spread of a set of haplotypes partially erased pre-existing diversity, but a high level of population (PhiST=0.332) and geographic (PhiCT=0.179) structuring persists. Correspondence analysis shows that three main clusters of populations can be identified: northern, eastern, and sub-Saharan Africans. Among the latter, the Khoisan, the Pygmies, and the northern Cameroonians are clearly distinct from a tight cluster formed by the Niger-Congo-speaking populations from western, central western, and southern Africa. Phylogeographic analyses suggest that a large component of the present Khoisan gene pool is eastern African in origin and that Asia was the source of a back migration to sub-Saharan Africa. Haplogroup IX Y chromosomes appear to have been involved in such a migration, the traces of which can now be observed mostly in northern Cameroon.
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Post by djoser-xyyman on Apr 20, 2010 12:40:28 GMT -5
mtDNA analysis in ancient Nubians supports the existence of gene flow between sub-Sahara and North Africa in the Nile Valley. Fox CL.
Universitat de Barcelona, Spain.
Abstract The Hpal (np3,592) mitochondrial DNA marker is a selectively neutral mutation that is very common in sub-Saharan Africa and is almost absent in North African and European populations. It has been screened in a Meroitic sample from ancient Nubia through PCR amplification and posterior enzyme digestion, to evaluate the sub-Saharan genetic influences in this population. From 29 individuals analysed, only 15 yield positive amplifications, four of them (26.7%) displaying the sub-Saharan African marker. Hpa 1 (np3,592) marker is present in the sub-Saharan populations at a frequency of 68.7 on average. Thus, the frequency of genes from this area in the Merotic Nubian population can be estimated at around 39% (with a confidence interval from 22% to 55%). The frequency obtained fits in a south-north decreasing gradient of Hpa I (np3,592) along the African continent. Results suggest that morphological changes observed historically in the Nubian populations are more likely to be due to the existence of south-north gene flow through the Nile Valley than to in-situ evolution.
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Post by djoser-xyyman on Apr 20, 2010 12:43:11 GMT -5
2008 Jun;136(2):128-37.
Regional differences in the distribution of the sub-Saharan, West Eurasian, and South Asian mtDNA lineages in Yemen. Cerný V, Mulligan CJ, Rídl J, Zaloudková M, Edens CM, Hájek M, Pereira L.
Institute of Archaeology of Academy of Sciences of Czech Republic, Prague, v.v.i., Prague 118 01, The Czech Republic. cerny@arup.cas.cz
Abstract Despite its key location for population movements out of and back into Africa, Yemen has not yet been sampled on a regional level for an investigation of sub-Saharan, West Eurasian, and South Asian genetic contributions. In this study, we present mitochondrial DNA (mtDNA) data for regionally distinct Yemeni populations that reveal different distributions of mtDNA lineages. An extensive database of mtDNA sequences from North and East African, Middle Eastern and Indian populations was analyzed to provide a context for the regional Yemeni mtDNA datasets. The groups of western Yemen appear to be most closely related to Middle Eastern and North African populations, while the eastern Yemeni population from Hadramawt is most closely related to East Africa. Furthermore, haplotype matches with Africa are almost exclusively confined to West Eurasian R0a haplogroup in southwestern Yemen, although more sub-Saharan L-type matches appear in more northern Yemeni populations. In fact, Yemeni populations have the highest frequency of R0a haplotypes detected to date, thus Yemen or southern Arabia may be the site of the initial expansion of this haplogroup. Whereas two variants of the sub-Saharan haplogroup M1 were detected only in southwestern Yemen close to the Bab el-Mandeb Strait, different non-African M haplotypes were detected at low frequencies (approximately 2%) in western parts of the country and at a higher frequency (7.5%) in the Hadramawt. We conclude that the Yemeni gene pool is highly stratified both regionally and temporally and that it has received West Eurasian, Northeast African, and South Asian gene flow. Copyright 2008 Wiley-Liss, Inc.
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Post by djoser-xyyman on Apr 20, 2010 12:46:10 GMT -5
1999 Apr;64(4):1166-76.
mtDNA analysis of Nile River Valley populations: A genetic corridor or a barrier to migration? Krings M, Salem AE, Bauer K, Geisert H, Malek AK, Chaix L, Simon C, Welsby D, Di Rienzo A, Utermann G, Sajantila A, Pääbo S, Stoneking M.
Max Planck Institute for Evolutionary Anthropology, Leipzig, and Department of Zoology, University of Munich, Munich, Germany.
Abstract To assess the extent to which the Nile River Valley has been a corridor for human migrations between Egypt and sub-Saharan Africa, we analyzed mtDNA variation in 224 individuals from various locations along the river. Sequences of the first hypervariable segment (HV1) of the mtDNA control region and a polymorphic HpaI site at position 3592 allowed us to designate each mtDNA as being of "northern" or "southern" affiliation. Proportions of northern and southern mtDNA differed significantly between Egypt, Nubia, and the southern Sudan. At slowly evolving sites within HV1, northern-mtDNA diversity was highest in Egypt and lowest in the southern Sudan, and southern-mtDNA diversity was highest in the southern Sudan and lowest in Egypt, indicating that migrations had occurred bidirectionally along the Nile River Valley. Egypt and Nubia have low and similar amounts of divergence for both mtDNA types, which is consistent with historical evidence for long-term interactions between Egypt and Nubia. Spatial autocorrelation analysis demonstrates a smooth gradient of decreasing genetic similarity of mtDNA types as geographic distance between sampling localities increases, strongly suggesting gene flow along the Nile, with no evident barriers. We conclude that these migrations probably occurred within the past few hundred to few thousand years and that the migration from north to south was either earlier or lesser in the extent of gene flow than the migration from south to north.
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Post by djoser-xyyman on Apr 20, 2010 12:51:35 GMT -5
2001 May-Jun;28(3):295-307.
Human mitochondrial DNA sequence variation in the Moroccan population of the Souss area. Brakez Z, Bosch E, Izaabel H, Akhayat O, Comas D, Bertranpetit J, Calafell F.
Laboratoire de Biologic Cellulaire et Moléculaire, Faculté des Sciences, Université Ibnou-Zohr, Agadir, Morocco.
Abstract BACKGROUND: Various populations have contributed to the present-day gene pool of Morocco, including the autochthonous Berber population, Phoenicians, Sephardic Jews, Bedouin Arabs and sub-Saharan Africans. OBJECTIVE: The primary objective of the study was to complete a genetic description of the Berber-speaking population in the Souss region of southern Morocco, based on mitochondrial DNA (mtDNA) sequence analysis. SUBJECTS AND METHODS: The first hypervariable segment of the mtDNA control region was sequenced in a sample of 50 individuals from the Souss Valley, and the results compared with the extensive body of data available on mtDNA sequence variation in Europe and sub-Saharan Africa. RESULTS: Thirty-four different sequences were found: an estimated 68% of the sequences occurred throughout Europe, West Asia and North Africa, 26% originated in sub-Saharan Africa, and 6% belonged to the North African specific haplogroup U6. The Souss Valley mtDNA sequences indicated the presence of two populations which expanded at different times: the West Eurasian sequences in the Souss sample had a smaller average number of pairwise differences than pairs of sub-Saharan sequences. CONCLUSION: Detailed knowledge of the possible geographic origin of each sequence facilitated an interpretation of both internal diversity parameters and between-population relationships. The sub-Saharan admixture in the Souss Valley matched the south-north cline of sub-Saharan influence in North Africa, also evident in the genetic distances of North African populations to Europeans and sub-Saharan Africans.
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Post by homeylu on May 2, 2010 10:58:38 GMT -5
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Post by djoser-xyyman on Jun 1, 2010 10:06:05 GMT -5
www.ncbi.nlm.nih.gov/pubmed/10885670Not sure where to put this. . . But it states than ALL humans have the capacity for light skin but this is supressed and light skin re-appears when the constraint (UV) is removed. The contradicts what some researchers affirm. The melanocortin 1 receptor (MC1R): more than just red hair. Rees JL. University of Edinburgh, Royal Infirmary, United Kingdom. jonathan.rees@ed.ac.uk Abstract The melanocortin 1 receptor, a seven pass transmembrane G protein coupled receptor, is a key control point in melanogenesis. Loss-of-function mutations at the MC1R are associated with a switch from eumelanin to phaeomelanin production, resulting in a red or yellow coat colour. Activating mutations, in animals at least, lead to enhanced eumelanin synthesis. In man, a number of loss-of-function mutations in the MC1R have been described. The majority of red-heads (red-haired persons) are compound heterozygotes or homozygotes for up to five frequent loss-of-function mutations. A minority of redheads are, however, only heterozygote. The MC1R is, therefore, a major determinant of sun sensitivity and a genetic risk factor for melanoma and non-melanoma skin cancer. Recent work suggests that the MC1R also shows a clear heterozygote effect on skin type, with up to 30% of the population harbouring loss-of-function mutations. Activating mutations of the MC1R in man have not been described. The MC1R is particularly informative and a tractable gene for studies of human evolution and migration. In particular, study of the MC1R may provide insights into the lightening of skin colour observed in most European populations. The world wide pattern of MC1R diversity is compatible with functional constraint operating in Africa, whereas the greater allelic diversity seen in non-African populations is consistent with neutral predictions rather than selection. Whether this conclusion is as a result of weakness in the statistical testing procedures applied, or whether it will be seen in other pigment genes will be of great interest for studies of human skin colour evolution. PMID: 10885670 [PubMed - indexed for MEDLINE] Attachments:
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Post by djoser-xyyman on Jun 1, 2010 14:45:18 GMT -5
Evidence for Variable Selective Pressures at MC1R Rosalind M. Harding,1 Eugene Healy,2,* Amanda J. Ray,2 Nichola S. Ellis,2 Niamh Flanagan,2 Carol Todd,2 Craig Dixon,2 Antti Sajantila,3 Ian J. Jackson,4 Mark A. Birch-Machin,2 and Jonathan L. Rees2,† It is widely assumed that genes that influence variation in skin and hair pigmentation are under selection. To date, the melanocortin 1 receptor (MC1R) is the only gene identified that explains substantial phenotypic variance in human pigmentation. Here we investigate MC1R polymorphism in several populations, for evidence of selection. We conclude that MC1R is under strong functional constraint in Africa, where any diversion from eumelanin production (black pigmentation) appears to be evolutionarily deleterious. Although many of the MC1R amino acid variants observed in non-African populations do affect MC1R function and contribute to high levels of MC1R diversity in Europeans, we found no evidence, in either the magnitude or the patterns of diversity, for its enhancement by selection; rather, our analyses show that levels of MC1R polymorphism simply reflect neutral expectations under relaxation of strong functional constraint [glow=red,2,300]outside[/glow] Africa.www.ncbi.nlm.nih.gov/pmc/articles/PMC1288200/Attachments:
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Post by djoser-xyyman on Jun 22, 2010 8:50:14 GMT -5
Mitochondrial DNA transit between West Asia and North Africa inferred from U6 phylogeography Nicole Maca-Meyer,1 Ana M González,1 José Pestano,2 Carlos Flores,1 José M Larruga,1 and Vicente M Cabrera1 Background World-wide phylogeographic distribution of human complete mitochondrial DNA sequences suggested a West Asian origin for the autochthonous North African lineage U6. We report here a more detailed analysis of this lineage, unraveling successive expansions that affected not only Africa but neighboring regions such as the Near East, the Iberian Peninsula and the Canary Islands. Results Divergence times, geographic origin and expansions of the U6 mitochondrial DNA clade, have been deduced from the analysis of 14 complete U6 sequences, and 56 different haplotypes, characterized by hypervariable segment sequences and RFLPs. Conclusions The most probable origin of the proto-U6 lineage was the Near East. Around 30,000 years ago it spread to North Africa where it represents a signature of regional continuity. Subgroup U6a reflects the first African expansion from the Maghrib returning to the east in Paleolithic times. Derivative clade U6a1 signals a posterior movement from East Africa back to the Maghrib and the Near East. This migration coincides with the probable Afroasiatic linguistic expansion. U6b and U6c clades, restricted to West Africa, had more localized expansions. U6b probably reached the Iberian Peninsula during the Capsian diffusion in North Africa. Two autochthonous derivatives of these clades (U6b1 and U6c1) indicate the arrival of North African settlers to the Canarian Archipelago in prehistoric times, most probably due to the Saharan desiccation. The absence of these Canarian lineages nowadays in Africa suggests important demographic movements in the western area of this Continent. And === Recently, molecular genetic research on North African populations has contributed new data to test the major issues proposed on archaeological, anthropological and linguistic grounds. The studies based on uniparental genetic markers have been particularly informative. Both, mitochondrial DNA (mtDNA) sequences [4,5], and Y-chromosome binary markers [6,7] detected specific North African haplotypes that confirm an ancient human colonization for this area and a sharp discontinuity between Northwest Africa and the Iberian Peninsula. From a mtDNA point of view, the most informative of these genetic markers is the North African clade U6. On the basis of complete mtDNA sequences, it has been proposed that U6 lineages, mainly found in North Africa, are the signatures of a return to Africa around *****39,000–52,000 ya [8].***** This stresses the importance of its detailed study in order to trace one of the earliest Caucasian arrivals to Africa. Although in moderate frequencies, the geographic range of this clade extends from the Near East to the Canary Islands, along the Atlantic shores of Northwest Africa and from the Sahel belt, including Ethiopia, to the southern Mediterranean rim. Out of this area, U6 has only been spotted in the Iberian Peninsula [9-12], Sicily [13], in the north European Ashkenazic Jews [14], and in Ibero-America. The presence in the latter is, most probably, the result of the Spanish and Portuguese colonization [15,16]. Attachments:
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