African and Levantine origins of Pakistani YAP+ Y chromosomes.

We surveyed 9 Pakistani subpopulations for variation on the nonrecombining portion of the Y chromosome. The polymorphic systems examined were the Y-chromosome Alu insertion polymorphism (YAP) at DYS287, 5 single nucleotide polymorphisms, and the tetranucleotide microsatellite DYS19. Y chromosomes carrying the YAP element (YAP+) were found in populations from southwestern Pakistan at frequencies ranging from 2% to 8%, whereas northeastern populations appeared to lack YAP+ chromosomes. In contrast to other South Asian populations, several Pakistani subpopulations had a high frequency of the DYS19*B allele, the most frequent allele in West Asian, North African, and European populations. The combination of alleles at all polymorphic sites gave rise to 9 YAP-DYS19 combination haplotypes in Pakistani populations, including YAP+ haplotypes 4-A, 4-B, 5-C, and 5-E. We hypothesize that the geographic distributions of YAP+ haplotypes 4 and 5 trace separate migratory routes to Pakistan: YAP+ haplotype 5 may have entered Pakistan from the Arabian Peninsula by means of migrations across the Gulf of Oman, whereas males possessing YAP+ haplotype 4 may have traveled over land from the Middle East. These inferences are consistent with ethnohistorical data suggesting that Pakistan's ethnic groups have been influenced by migrations from both African and Levantine source populations.     

Characterization of ancestral and derived Y-chromosome haplotypes of New World native populations.

We analyze the allelic polymorphisms in seven Y-specific microsatellite loci and a Y-specific alphoid system with 27 variants (alphah I-XXVII), in a total of 89 Y chromosomes carrying the DYS199T allele and belonging to populations representing Amerindian and Na-Dene linguistic groups. Since there are no indications of recurrence for the DYS199C-->T transition, it is assumed that all DYS199T haplotypes derive from a single individual in whom the C-->T mutation occurred for the first time. We identified both the ancestral founder haplotype, 0A, of the DYS199T lineage and seven derived haplogroups diverging from the ancestral one by one to seven mutational steps. The 0A haplotype (5.7% of Native American chromosomes) had the following constitution: DYS199T, alphah II, DYS19/13, DYS389a/10, DYS389b/27, DYS390/24, DYS391/10, DYS392/14, and DYS393/13 (microsatellite alleles are indicated as number of repeats). We analyzed the Y-specific microsatellite mutation rate in 1,743 father-son transmissions, and we pooled our data with data in the literature, to obtain an average mutation rate of.0012. We estimated that the 0A haplotype has an average age of 22,770 years (minimum 13,500 years, maximum 58,700 years). Since the DYS199T allele is found with high frequency in Native American chromosomes, we propose that 0A is one of the most prevalent founder paternal lineages of New World aborigines.     

Genetic variation of the Y chromosome in Chibcha-speaking Amerindians of Costa Rica and Panama

Genetic variation of the Y chromosome in five Chibchan tribes (Bribri, Cabecar, Guaymi, Huetar, and Teribe) of Costa Rica and Panama was analyzed using six microsatellite loci (DYS19, DYS389A, DYS389B, DYS390, DYS391, and DYS393), the Y-chromosome-specific alphoid system (alphah), the Y-chromosome Alu polymorphism (YAP), and a specific pre-Columbian transition (C-->T) (M3 marker) in the DYS 199 locus that defines the Q-M3 haplogroup. Thirty-nine haplotypes were found, resulting in a haplotype diversity of 0.937. The Huetar were the most diverse tribe, probably because of their high levels of interethnic admixture. A candidate founder Y-chromosome haplotype was identified (15.1% of Chibchan chromosomes), with the following constitution: YAP-, DYS199*T, alphah-II, DYS19*13, DYS389A*17, DYS389B*10, DYS390*24, DYS391*10, and DYS393*13. This haplotype is the same as the one described previously as one of the most frequent founder paternal lineages in native American populations. Analysis of molecular variance indicated that the between-population variation was smaller than the within-population variation, and the comparison with mtDNA restriction data showed no evidence of differential structuring between maternally and paternally inherited genes in the Chibchan populations. The mismatch-distribution approach indicated estimated coalescence times of the Y chromosomes of the Q-M3 haplogroup of 3,113 and 13,243 years before present; for the mtDNA-restriction haplotypes the estimated coalescence time was between 7,452 and 9,834 years before present. These results are compatible with the suggested time for the origin of the Chibchan group based on archeological, linguistic, and genetic evidence.     

Y chromosomal DNA variation and the peopling of Japan.

Four loci mapping to the nonrecombining portion of the Y chromosome were genotyped in Japanese populations from Okinawa, the southernmost island of Japan; Shizuoka and Aomori on the main island of Honshu; and a small sample of Taiwanese. The Y Alu polymorphic (YAP) element is present in 42% of the Japanese and absent in the Taiwanese, confirming the irregular distribution of this polymorphism in Asia. Data from the four loci were used to determine genetic distances among populations, construct Y chromosome haplotypes, and estimate the degree of genetic diversity in each population and on different Y chromosome haplotypes. Evolutionary analysis of Y haplotypes suggests that polymorphisms at the YAP (DYS287) and DXYS5Y loci originated a single time, whereas restriction patterns at the DYS1 locus and microsatellite alleles at the DYS19 locus arose more than once. Genetic distance analysis indicated that the Okinawans are differentiated from Japanese living on Honshu. The data support the hypotheses that modern Japanese populations have resulted from distinctive genetic contributions involving the ancient Jomon people and Yayoi immigrants from Korea or mainland China, with Okinawans experiencing the least amount of admixture with the Yayoi. It is suggested that YAP+ chromosomes migrated to Japan with the Jomon people > 10,000 years ago and that a large infusion of YAP- chromosomes entered Japan with the Yayoi migration starting 2,300 years ago. Different degrees of genetic diversity carried by these two ancient chromosomal lineages may be explained by the different life-styles (hunter-gatherer versus agriculturalist). of the migrant groups, the size of the founding populations, and the antiquities of the founding events.     

A short tandem repeat-based phylogeny for the human Y chromosome

Human Y-chromosomal short tandem repeat (STR) data provide a potential model system for the understanding of autosomal STR mutations in humans and other species. Yet, the reconstruction of STR evolution is rarely attempted, because of the absence of an appropriate methodology. We here develop and validate a phylogenetic-network approach. We have typed 256 Y chromosomes of indigenous descent from Africa, Asia, Europe, Australia, and highland Papua New Guinea, for the STR loci DYS19, DXYS156Y, DYS389, DYS390, DYS392, and DYS393, as well as for five ancient biallelic mutation events: two poly (A) length variants associated with the YAP insertion, two independent SRY-1532 mutations, and the 92R7 mutation. We have used our previously published pedigree data from 11,000 paternity-tested autosomal STR-allele transfers to produce a two-class weighting system for the Y-STR loci that is based on locus lengths and motif lengths. Reduced-median-network analysis yields a phylogeny that is independently supported by the five biallelic mutations, with an error of 6%. We find the earliest branch in our African San (Bushmen) sample. Assuming an age of 20,000 years for the Native American DYS199 T mutation, we estimate a mutation rate of 2.6x10-4 mutations/20 years for slowly mutating Y STRs, approximately 10-fold slower than the published average pedigree rate.     

The Dual Origin and Siberian Affinities of Native American Y Chromosomes

The Y chromosomes of 549 individuals from Siberia and the Americas were analyzed for 12 biallelic markers, which defined 15 haplogroups. The addition of four microsatellite markers increased the number of haplotypes to 111. The major Native American founding lineage, haplogroup M3, accounted for 66% of male Y chromosomes and was defined by the biallelic markers M89, M9, M45, and M3. The founder haplotype also harbored the microsatellite alleles DYS19 (10 repeats), DYS388 (11 repeats), DYS390 (11 repeats), and DYS391 (10 repeats). In Siberia, the M3 haplogroup was confined to the Chukotka peninsula, adjacent to Alaska. The second major group of Native American Y chromosomes, haplogroup M45, accounted for about one-quarter of male lineages. M45 was subdivided by the biallelic marker M173 and by the four microsatellite loci alleles into two major subdivisions: M45a, which is found throughout the Americas, and M45b, which incorporates the M173 variant and is concentrated in North and Central America. In Siberia, M45a haplotypes, including the direct ancestor of haplogroup M3, are concentrated in Middle Siberia, whereas M45b haplotypes are found in the Lower Amur River and Sea of Okhotsk regions of eastern Siberia. Among the remaining 5% of Native American Y chromosomes is haplogroup RPS4Y-T, found in North America. In Siberia, this haplogroup, along with haplogroup M45b, is concentrated in the Lower Amur River/Sea of Okhotsk region. These data suggest that Native American male lineages were derived from two major Siberian migrations. The first migration originated in southern Middle Siberia with the founding haplotype M45a (10-11-11-10). In Beringia, this gave rise to the predominant Native American lineage, M3 (10-11-11-10), which crossed into the New World. A later migration came from the Lower Amur/Sea of Okhkotsk region, bringing haplogroup RPS4Y-T and subhaplogroup M45b, with its associated M173 variant. This migration event contributed to the modern genetic pool of the Na-Dene and Amerinds of North and Central America.     

The Geographic Distribution of Human Y Chromosome Variation

We examined variation on the nonrecombining portion of the human Y chromosome to investigate human evolution during the last 200,000 years. The Y-specific polymorphic sites included the Y Alu insertional polymorphism or ``YAP' element (DYS287), the poly(A) tail associated with the YAP element, three point mutations in close association with the YAP insertion site, an A-G polymorphic transition (DYS271), and a tetranucleotide microsatellite (DYS19). Global variation at the five bi-allelic sites (DYS271, DYS287, and the three point mutations) gave rise to five ``YAP haplotypes' in 60 populations from Africa, Europe, Asia, Australasia, and the New World (n = 1500). Combining the multi-allelic variation at the microsatellite loci (poly(A) tail and DYS19) with the YAP haplotypes resulted in a total of 27 ``combination haplotypes'. All five of the YAP haplotypes and 21 of the 27 combination haplotypes were found in African populations, which had greater haplotype diversity than did populations from other geographical locations. Only subsets of the five YAP haplotypes were found outside of Africa. Patterns of observed variation were compatible with a variety of hypotheses, including multiple human migrations and range expansions.     

Evaluation of the contribution of D9S1120 to anthropological studies in Native American populations

The D9S1120 locus exhibits a population-specific allele of 9 repeats (9RA) in all Native American and two Siberian populations currently studied, but it is absent in other worldwide populations. Although this feature has been used in anthropological genetic studies, its impact on the evaluation of the structure and genetic relations among Native American populations has been scarcely assessed. Consequently, the aim of this study was to evaluate the anthropological impact of D9S1120 when it was added to STR population datasets in Mexican Native American groups. We analyzed D9S1120 by PCR and capillary electrophoresis (CE) in 1117 unrelated individuals from 13 native groups from the north and west of Mexico. Additional worldwide populations previously studied with D9S1120 and/or 15 autosomal STRs (Identifier kit) were included for interpopulation analyses. We report statistical results of forensic importance for D9S1120. On average, the modal alleles were the Native American-specific allele 9RA (0.3254) and 16 (0.3362). Genetic distances between Native American and worldwide populations were estimated. When D9S1120 was included in the 15 STR population dataset, we observed improvements for admixture estimation in Mestizo populations and for representing congruent genetic relationships in dendrograms. Analysis of molecular variance (AMOVA) based on D9S1120 confirms that most of the genetic variability in the Mexican population is attributable to their Native American backgrounds, and allows the detection of significant intercontinental differentiation attributed to the exclusive presence of 9RA in America. Our findings demonstrate the contribution of D9S1120 to a better understanding of the genetic relationships and structure among Mexican Native groups.     

Three major lineages of Asian Y chromosomes: implications for the peopling of east and southeast Asia

DNA variation on the non-recombining portion of the Y chromosome was examined in 610 male samples from 14 global populations in north, east, and southeast Asia, and other regions of the world. Eight haplotypes were observed by analyses of seven biallelic polymorphic markers ( DYS257(108), DYS287, SRY(4064), SRY(10831), RPS4Y(711), M9, and M15) and were unevenly distributed among the populations. Maximum parsimony tree for the eight haplotypes showed that these haplotypes could be classified into four distinct lineages characterized by three key mutations: an insertion of the Y Alu polymorphic (YAP) element at DYS287, a C-to-G transversion at M9, and a C-to-T transition at RPS4Y(711). Of the four lineages, three major lineages (defined by the allele of YAP(+), M9-G, and RPS4Y-T, respectively) accounted for 98.6% of the Asian populations studied, indicating that these three paternal lineages have contributed to the formation of modern Asian populations. Moreover, phylogenetic analysis revealed three monophyletic Asian clusters, which consisted of north Asian, Japanese, and Han Chinese/southeast Asian populations, respectively. Coalescence analysis in the haplotype tree showed that the estimated ages for three key mutations ranged from 53,000 to 95,000 years, suggesting that the three lineages were separated from one another during early stages of human evolutionary history. The distribution patterns of the Y-haplotypes and mutational ages for the key markers suggest that three major groups with different paternal ancestries separately migrated to prehistoric east and southeast Asia.     

Genetic differentiation in South Amerindians is related to environmental and cultural diversity: evidence from the Y chromosome

The geographic structure of Y-chromosome variability has been analyzed in native populations of South America, through use of the high-frequency Native American haplogroup defined by the DYS199-T allele and six Y-chromosome-linked microsatellites (DYS19, DYS389A, DYS389B, DYS390, DYS391, and DYS393), analyzed in 236 individuals. The following pattern of within- and among-population variability emerges from the analysis of microsatellite data: (1) the Andean populations exhibit significantly higher levels of within-population variability than do the eastern populations of South America; (2) the spatial-autocorrelation analysis suggests a significant geographic structure of Y-chromosome genetic variability in South America, although a typical evolutionary pattern could not be categorically identified; and (3) genetic-distance analyses and the analysis of molecular variance suggest greater homogeneity between Andean populations than between non-Andean ones. On the basis of these results, we propose a model for the evolution of the male lineages of South Amerindians that involves differential patterns of genetic drift and gene flow. In the western part of the continent, which is associated with the Andean area, populations have relatively large effective sizes and gene-flow levels among them, which has created a trend toward homogenization of the gene pool. On the other hand, eastern populations-settled in the Amazonian region, the central Brazilian plateau, and the Chaco region-have exhibited higher rates of genetic drift and lower levels of gene flow, with a resulting trend toward genetic differentiation. This model is consistent with the linguistic and cultural diversity of South Amerindians, the environmental heterogeneity of the continent, and the available paleoecological data.     

Analysis of Y-chromosomal diallelic loci polymorphism in populations of the Volga-Ural region

Three diallelic polymorphisms of human Y chromosome, DYS287 (Y Alu polymorphism, YAP), T/C transition at the RBF5 locus (Tat), and G/A transition at the LLY22 locus, were studied in eight ethnic populations of the Volga-Ural region, representing Turkic (Bashkirs, Tatars, and Chuvashes) and Finno-Ugric (Maris, Mordovians, Udmurts, Komi-Zyryans, and Komi-Permyaks) branches of the Uralic linguistic family, and in the group of Slavic migrants, belonging to the Indo-European linguistic family (Russians). Ethnic populations of the Volga-Ural region were characterized by a low frequency of the Y chromosome Alu insertion. Examination of an association between the Alu polymorphism and Tat mutation revealed absolute C/YAP linkage. Analysis of the haplotype frequency distribution patterns constructed from the data on the DYS287 and RBF5 polymorphisms revealed substantial differences between Udmurts and the other ethnic populations. The differences were also observed between Komi-Zyryans and the populations of Bashkirs, Mordovians, Komi-Permyaks, and Russians. Analysis of the degree of genetic differentiation pointed to high level of genetic differentiation of the male lineages of the Finno-Ugric ethnic groups. The data on the linkage between mutations of the RBF5 and the LLY22 loci indicated the common origin of the Tat mutation in Bashkirs, Mordovians, Udmurts, and Komi-Zyryans, and of a number of ancestral C allele-bearing chromosomes in Tatars, Maris, and Chuvashes.     

Origin of Amerindian Y-chromosomes as inferred by the analysis of six polymorphic markers

We analysed the frequency of six Y-specific polymorphisms in 105 Amerindian males from seven different populations, 42 Caucasian males, and a small number of males of African, Chinese, and Melanesian origin. The combination of three of the six polymorphisms studied produced four different Y-haplogroups. The haplogroup A (non-variant) was the most frequent one. Eighty-five percent of Amerindians showing haplogroup A have the alphoid II (αhII) and the DYS19A Y-specific markers, an association that is found only in 10% of Caucasians and that has not been detected in Asiatics and Africans. Haplogroups C (YAP+) and D (YAP+ plus an A → G transition in the locus DYS271) are of African origin. Four percent of Amerindians and ∼12% of Caucasians showed haplogroup C; ∼1% of Amerindians and ∼2% of Caucasians had haplogroup D. Haplogroup B is characterized by a C → T transition in nucleotide position 373 of the SRY gene domain; this haplogroup is found in Caucasians (∼12%) and Amerindians (∼4%). None of the Amerindians exhibiting the haplogroups B, C, or D show the haplotype αhII/DYS19A. By haplotyping the Alu insert and the DNA region surrounding the insert in YAP+ individuals, we could demonstrate that Amerindian Y chromosomes bearing African markers (haplogroups C and D) are due to recent genetic admixture. Most non-αhII/DYSl9A Amerindian Y-chromosomes in haplogroup A and most cases in haplogroup B are also due to gene flow. We show that haplotype αhII/DYS19A is in linkage disequilibrium with a C → T transition in the locus DYS199. Our results suggest that most Amerindian Y-chromosomes derive from a single paternal lineage characterized by the αhII/DYS19A/DYS199T Amerindian-specific haplotype. The analysis of a larger sample of native American Y-chromosomes will be required in order to confirm or correct this hypothesis. Am J Phys Anthropol 102:79–89, 1997. © 1997 Wiley-Liss, Inc.     

Haplotypes of two diallelic Y chromosome loci in the indigenous and migrant populations of Siberia

Two diallelic Y-chromosome markers, the Y Alu polymorphism (YAP) and the T-C transition (Tat), were analyzed in the indigenous (Tuvinian, Buryat, Northern Altaic, and Tatar) and migrant (Slavic) populations of Siberia. A high frequency of the allele C was revealed in several indigenous populations (25-55%) and in Russians (20.8%). The YAP+ allele occurred at a surprisingly high frequency (31.4%) and was completely linked with the C allele in Buryats. The YAP+ chromosome was also found in the Tuvinian population (1.5%). The two diallelic loci showed a marked linkage disequilibrium (D = 92.4%) in the total sample. The YAP-/T and YAP-/C haplotypes prevailed in both indigenous and migrant populations: their respective frequencies were 80.4 and 19.6% in the Slavic population and 71.8 and 19.9%, respectively, in the indigenous one. The YAP+/C (7.8%) and YAP+/T (0.5%) haplotypes were found only in the indigenous population. An appreciable heterogeneity in haplotype frequency distribution between regional subpopulations was revealed in Russians, Tuvinians, and Buryats. The origin and evolution of Y-chromosome lines in Northern Asia are considered.     

Selected di- and tetranucleotide microsatellites from chromosomes 7, 12, 14, and Y in various Eurasian populations

Microsatellite polymorphisms of nine Eurasian populations (>1200 chromosomes) were analyzed for the following loci: i) intronic (gt) _n stretches of three T cell receptor (TCR) B loci on chromosome 7 (TCRBV6S1, TCRBV6S3, TCRBV6S7); ii) an intergenic (gt) _n repeat in the region between the TCRDV3 and TCRAJ61 elements on chromosome 14; iii) two tetranucleotide simple repeats (D12S66, D12S67), not linked to known genes on chromosome 12; iv) a Y-chromosomal (gata) _n polymorphism (DYS19). In general, allele frequencies and heterozygosity rates were similar, but specific alleles were missing in one or more populations. Distinct DYS19 alleles predominated in particular cohorts. Different allele frequencies were observed for the TCR loci in European and Asian populations. Tetranucleotide polymorphisms were distributed normally, whereas TCR alleles displayed bimodal frequency profiles. For TCRBV6S1 and TCRBV6S7, this profile reflects a diallelic protein polymorphism that correlates exactly with the length of the intronic repeats.     

我国东北地区3个群体DYS390多态位点的遗传学研究

目的　研究中国群体Y染色体微卫星位点 DYS390遗传多态性 ,可以用于追溯人类进化上的父系祖先 ,也可以为人类基因组和法医学等研究积累数据。方法　采用 PCR技术扩增微卫星DNA片段 ,再经变性凝胶电泳及银染方法 ,对我国东北地区汉族、蒙古族及朝鲜族 3个群体的1 0 2例男性个体的 DYS390位点的遗传多态性进行了研究。结果　除汉族群体发现 5种等位基因外 ,朝鲜族和蒙古族群体均检出 4种。在汉族群体中 ,我们检出 1例具223bp等位基因。等位基因频率分布在汉族、朝鲜族以211bp的频率为最高 ,分别为0.439和0.451 ;而蒙古族群体则以215bp的频率为最高 (0.433)。结论　 3个群体之间 DYS390位点等位基因频率无显著性差异 ( Fisher精确概率检验 :P=0.930 )。 3个群体中DYS390位点 5种等位基因的分化程度以223bp为最高 ,分化程度最低的为211bp。聚类分析表明3个群体的父系亲缘关系较为密切 ,其中以汉族与朝鲜族之间的遗传距离最近。     

Divergent Human Y-Chromosome Microsatellite Evolution Rates

In this work, we analyze several characteristics influencing the low variability of the microsatellite DYS19 in the major founder Amerindian Y chromosome lineage containing the point mutation DYS199-T. Variation of DYS19 was compared with that of five other Y-linked tetranucleotide repeat loci (DYS389A, DYS389B, DYS390, DYS391, and DYS393) in the DYS199-T lineage. All the other microsatellites showed significantly higher levels of variability than DYS19 as measured by gene diversity and repeat number variance. Moreover, we had previously shown that DYS19 had high diversity in Brazilians and in several other populations worldwide. Thus, the slow DYS19 evolution in the DYS199-T lineage seems to be both locus and allele specific. To understand the slow DYS19 evolutionary rate, the microsatellite loci were compared according to their mapping on the Y chromosome and also on the basis of structural aspects such as the base composition of the repeat motif and flanking regions and the degree of perfection and size (repeat number) of the variable blocks. The only observed difference that might be related to the low DYS19 variability is its small average number of repeats, a value expected to be closer to the founder DYS19 allele in the DYS199-T lineage. These data were also compared to other derived Y lineages. The Tat-C lineage displayed a lower DYS19 variability correlated to a small average repeat number, while in the DYS234-G lineage, a high DYS19 variability was found associated to a larger average repeat number. This approach reveals that evolution of Y microsatellites in lineages defined by slowly evolving markers, such as point mutations, can be greatly influenced by the size (number of repeats of the variable block) of the founder allele in each microsatellite locus. Thus lineage-dating methods using microsatellite variation should be practiced with great care. Received: 7 November 1998 / Accepted: 9 April 1999     

Genetic diversity in an Andean population from Peru and regional migration patterns of Amerindians in South America: data from Y chromosome and mitochondrial DNA

The genetic variability of a Quechua-speaking Andean population from Peru was examined on the basis of four Y chromosome markers and restriction sites that define the Amerindian mitochondrial DNA (mtDNA) haplogroups. Forty-nine out of 52 (90.4%) individuals had mtDNA which belonged to one of the four common Amerindian haplogroups, with 54% of the samples belonging to haplogroup B. Among 25 males, 12 had an Amerindian Y chromosome, which exists as four haplotypes defined on the basis of the DYS287, DYS199, DYS392 and DYS19 markers, three of which are shared by Amazonian Amerindians. Thus, there is a clear directionality of marriages, with an estimated genetic admixture with non-Amerindians that is 9 times lower for mtDNA than for Y chromosome DNA. The comparison of mtDNA of Andean Amerindians with that of people from other regions of South America in a total of 1,086 individuals demonstrates a geographical pattern, with a decreasing frequency of A and C haplotypes and increasing frequency of the D haplotype from the north of the Amazon River to the south of the Amazon River, reaching the lowest and the highest frequencies, respectively, in the more southern populations of Chile and Argentina. Conversely, the highest and lowest frequencies of the haplogroup B are found, respectively, in the Andean and the North Amazon regions, and it is absent from some southern populations, suggesting that haplotypes A, C and D, and haplotype B may have been dispersed by two different migratory routes within the continent.     

Admixture and Genetic Diversity Distribution Patterns of Non-Recombining Lineages of Native American Ancestry in Colombian Populations

Genetic diversity of present American populations results from very complex demographic events involving different types and degrees of admixture. Through the analysis of lineage markers such as mtDNA and Y chromosome it is possible to recover the original Native American haplotypes, which remained identical since the admixture events due to the absence of recombination. However, the decrease in the effective population sizes and the consequent genetic drift effects suffered by these populations during the European colonization resulted in the loss or under-representation of a substantial fraction of the Native American lineages. In this study, we aim to clarify how the diversity and distribution of uniparental lineages vary with the different demographic characteristics (size, degree of isolation) and the different levels of admixture of extant Native groups in Colombia. We present new data resulting from the analyses of mtDNA whole control region, Y chromosome SNP haplogroups and STR haplotypes, and autosomal ancestry informative insertion-deletion polymorphisms in Colombian individuals from different ethnic and linguistic groups. The results demonstrate that populations presenting a high proportion of non-Native American ancestry have preserved nevertheless a substantial diversity of Native American lineages, for both mtDNA and Y chromosome. We suggest that, by maintaining the effective population sizes high, admixture allowed for a decrease in the effects of genetic drift due to Native population size reduction and thus resulting in an effective preservation of the Native American non-recombining lineages.     

Autosomal, mtDNA, and Y-chromosome diversity in Amerinds: pre- and post-Columbian patterns of gene flow in South America

To evaluate sex-specific differences in gene flow between Native American populations from South America and between those populations and recent immigrants to the New World, we examined the genetic diversity at uni- and biparental genetic markers of five Native American populations from Colombia and in published surveys from native South Americans. The Colombian populations were typed for five polymorphisms in mtDNA, five restriction sites in the beta-globin gene cluster, the DQA1 gene, and nine autosomal microsatellites. Elsewhere, we published results for seven Y-chromosome microsatellites in the same populations. Autosomal polymorphisms showed a mean G(ST) of 6.8%, in agreement with extensive classical marker studies of South American populations. MtDNA and Y-chromosome markers resulted in G(ST) values of 0.18 and 0.165, respectively. When only Y chromosomes of confirmed Amerind origin were used in the calculations (as defined by the presence of allele T at locus DYS199), G(ST) increased to 0.22. G(ST) values calculated from published data for other South American natives were 0.3 and 0.29 for mtDNA and Amerind Y chromosomes, respectively. The concordance of these estimates does not support an important difference in migration rates between the sexes throughout the history of South Amerinds. Admixture analysis of the Colombian populations suggests an asymmetric pattern of mating involving mostly immigrant men and native women.