Keywords: admixture dynamics, mtDNA, Y-chromosome markers

Population samples and DNA extraction

The history of Porto Alegre (30°5' S, 5°10' W), the capital of the Brazilian state of Rio Grande do Sul, dates from 1730 when Jerônimo de Ornellas, an immigrant from Madeira Island, received a large plot of land (sesmaria) in this area from the Portuguese crown. The little village that was subsequently formed showed significant population growth only after the arrival of ~500 couples from the Azores archipelago (another Portuguese colony), from 1752 to 1754 (Flores, 1996). The importance of the Azorian migration to Rio Grande do Sul, especially Porto Alegre, is illustrated byLaytano (1974), who stated that in 1780 about 55% of the 18,000 inhabitants of the town were Azorian or of Azorian-descendent. The pre-Columbian inhabitants, the Guarani Indians, were displaced, although in other regions of the state they, as well as other natives, were still present (Noelliet al., 1997). Subsequent waves of European migration, especially from Portugal, Spain, Italy and Germany, contributed to the growth of Porto Alegre and nearby cities. The presence of African slaves is also mentioned in historical records (Nogueról, 2005), although their proportion relative to the total population is unknown. Currently, the urban complex formed by the capital and neighboring cities has 3,152,596 inhabitants, 7% and 88% of whom are classified as blacks (pretos, in Portuguese) and whites (brancos), respectively (Brazilian Institute of Geography and Statistics-IBGE, 2000). In Brazil, skin color rather than ancestry is used to define an equivalent to “race”, and in the present study the word “black” will be used to refer topretos and any person identified and/or self-identified with some other term that suggests African ancestry, such asmulato orpardo. “White” will be used to define those who, based on their physical traits and information, show no admixture with non-Europeans.

Two hundred and three unrelated individuals living in Porto Alegre and its metropolitan region, phenotypically classified as white by the interviewer of the research group, were studied. DNA was extracted from whole blood according toLahiri and Nurnberger (1991) or from saliva using QIAamp® kits (QIAGEN), according to the manufacturer's instructions. This investigation was approved by the Brazilian National Ethics Commission (CONEP Resolution no. 1333/2002).

Y- chromosome markers

Hünemeieret al. (2007) recently presented and discussed the African portion of the Y-chromosomes and mtDNA lineages of a sample of 107 blacks from the same city. Here, we investigated additional Y-chromosome polymorphisms (see below) to characterize the non-African portion of the Y-chromosomes of this sample, and also considered the mtDNA lineages classified as Amerindian or European. This procedure standardized the set of uniparental markers investigated in the two samples, thereby allowing comparative analyses.

Two hundred and three white men were genotyped for 13 binary loci (11 single nucleotide polymorphisms or SNPs: 92R7, M3, M242, M9, M17, M170, M173, M213, M269, SRY2627, M2, and two insertion/deletions, YapALU and 12f2) located in the non-recombinant region of the Y-chromosome (NRY). These markers define well the most common and widespread African, European and Native American Y-chromosomes. Genotyping was done according to the hierarchical order of markers presented byJobling and Tyler-Smith (2003) using the primers and conditions described inHammer and Horai (1995),Underhillet al. (1996,2001),Hurleset al. (1999),Thomaset al. (1999),Rosseret al. (2000),Bortoliniet al. (2003),Floreset al. (2003),Montielet al. (2005), and Kayseret al. (2005). Haplogroups P*(xQ3,R1), Q3*, K(xP), Q*(xQ3), R1a1*(xDE), I*(xP,K,J), R1*(xR1a1,R1b3), F(xI,J,K,P), R1b3*(xR1b3f), R1b3f, E3a*, DE*(E3a) and J* were established using the markers indicated above in the order given. According toJobling and Tyler-Smith (2003), designations such as P*(xQ3, R1) indicate partial typing of markers in a haplogroup and, in the present case, describes all chromosomes in clade P* except Q3* and R1*. We also investigated 11 of the biallelic loci indicated above (92R7, M3, M242, M9, M17, M170, M173, M213, M269, SRY2627 and 12f2) to characterize the non-African portion of the Y-chromosomes in the black sample previously studied byHünemeieret al. (2007).

Mitochondrial DNA

The first hypervariable segment (HVS-I) of the mtDNA control region was sequenced in a subset of 172 white individuals using primers and conditions previously described byMarreroet al. (2005). The sequence reactions were run in an automated ABI 310 sequencer. Both DNA strands were sequenced from positions 16050 to 16391, since this is the region for which most of the comparative information is available. Individuals with the “C-stretch” between positions 16183-16193, which is caused by the 16189C substitution, were re-sequenced in each direction so that each base was determined twice.

The sequences were checked manually, and validated by using the CHROMAS LITE 2.0 program. Alignment relative to the revised Cambridge Reference Sequence (Andrewset al., 1999) was done using the BIOEDIT software (Hall, 1999). The filtering procedure described byBandeltet al. (2002) was used to check the quality of the sequences and eliminate artifacts introduced during sequencing and editing. After filtering, the relationships between the lineages were examined with the NETWORK 4.2.0.0. program using the median-joining algorithm (Bandeltet al., 1999). Weight networks showing star tree patterns, together with other criteria such as those suggested byYaoet al. (2004), ensured that the data were essentially free of artifacts. The HVS-I sequences were classified into haplogroups according to recommended criteria (Bandeltet al., 2002;Salaset al., 2002,2004; Kivisildet al., 2002;Torroniet al., 2006).

Data analysis

Y-SNP and mtDNA haplogroup frequencies were obtained by counting. Estimates of parental continental contributions in the paternal and maternal data sets were obtained directly since the major haplogroups of mtDNA and Y-SNP are geographically specific. Population relationships were estimated through F_ST genetic distances using Arlequin version 3.01 (Schneideret al., 2000;Excoffieret al., 2005) and their statistical significance was assessed by permutation using 10,000 runs.

Y-chromosome biallelic polymorphisms (SNPs)

Based on the Y-chromosome distribution (Table 1), the most frequent haplogroup in Porto Alegre whites was R1b3* (51%), which was also the most common haplogroup found in another Brazilian city (Rio de Janeiro), as well as in the Azores and Portugal. The frequency of this haplogroup was lower (~13%) in Porto Alegre blacks.

To test the hypothesis of random haplogroup distribution among populations we computed F_ST values based on the major hierarchical clustering for these analyses. There were no significant differences between Porto Alegre whites and those of the Azores, Portugal or Spain (F_ST = -0.00162, p = 0.6126; F_ST = 0.00235, p = 0.1622; F_ST = 0.00345, p = 0.1261, respectively), although the Porto Alegre white prevalences differ significantly from those of the other European countries considered. The difference between Porto Alegre and Rio de Janeiro was also significant (F_ST = 0.0120, p = 0.0090), but when the African (E3a, B*, and DE) and Amerindian (Q* and Q3*) haplogroups are excluded this significance disappeared (F_ST = 0.0056, p = 0.1441). Surprisingly, the haplogroups of European origin detected in Porto Alegre blacks were significantly different from those found in whites of the same city (F_ST = 0.1562, p = 0.000), and from those observed in Iberian populations. However, since the number of blacks studied was small (30), it is probable that these differences reflect sampling error rather than any phenomenon of the admixture process. The African portion of the Y-chromosomes of this black sample has been described in detail byHünemeieret al. (2007).

Mitochondrial DNA

Multiple alignment with the reference sequence (Andrewset al., 1999) allowed the identification of 105 mtDNA lineages in white individuals (Table 2). This table also shows the non-African lineages identified in blacks, as well as those shared by the two samples.

For 35 of the 69 European lineages (51%), identical matches were found for data in the literature from countries with an important history of migration to Rio Grande do Sul (Portugal/Azores, Spain, Italy, and Germany; data fromCrespilloet al., 2000;Pereiraet al., 2000;Mogentale-Profiziet al., 2001;Brehmet al., 2003;Poetschet al., 2003;Picornellet al., 2005;Pichleret al., 2006). Most of these haplotypes (25; 71%) perfectly matched more than one of the European populations. Four (lineages #12, #13, #38 and #68), three (#36, #62 and #63), two (#2 and #38), and one (#14) of the haplotypes found in Porto Alegre (Table 2) exclusively matched those found in the Azores, Portugal, Spain, and Italy, respectively. Only two lineages of European origin (#49 and #50) present in Porto Alegre blacks were not observed in whites from the same city or in any of the European populations considered here. As with the Y markers, the mtDNA data also revealed that the Azorian presence in Porto Alegre was clearly detectable regardless of the demographic and cultural changes that occurred after the initial foundation/colonization of the city.

The same analysis with the 14 lineages of African origin found in the white sample revealed that 57% of them had perfect matches with those found in the regions of slave importation to Brazil (West, West-Central, and Southeast Africa;Salaset al., 2002;Plazaet al., 2004;Rosaet al., 2004;Belezaet al., 2005;Coiaet al., 2005;Jacksonet al., 2005). Three lineages (# 103, #104, and #116) exclusively matched those found in Angola, Cabinda, and Mozambique, countries inhabited by peoples who speak Bantu languages (Salaset al., 2002;Plazaet al., 2004;Belezaet al., 2005). Another lineage (#110) was also probably of Bantu origin since it occurs in Mozambique and in the Bassa ethnic group of Cameroon. Lineage #113 matched one found only in Guinea Bissau, whereas # 106 matched another found in Sierra Leone, both of which are West African countries (Rosaet al., 2004;Jacksonet al., 2005). Two lineages (#108 and #109) had a geographical origin that was difficult to define since they occur in all sub-Saharan Africa. Only four African lineages were shared between the black and white Porto Alegre groups, with all four occurring in Africa and/or other Brazilian populations (Salaset al., 2002;Plazaet al., 2004;Rosaet al., 2004;Belezaet al., 2005;Coiaet al., 2005;Jacksonet al., 2005;Gonçalveset al., 2008).

The four major Amerindian haplogroups were detected among Porto Alegre whites (A = 28%; B = 22%, C = 47%, D = 3%), whereas haplogroup A was absent among blacks (B = 19%, C = 69% and D = 12%). Lineage #87 was the most common in both samples. Since this lineage contained the mutations that defined the C nodal branch, it matched several sequences found in admixed populations from southern Brazil, and in individuals from the Tupian and Jêan tribes; these different matches precluded identification of the precise origin of this lineage (Alves-Silvaet al., 2000;Marreroet al., 2005,2007a,b). On the other hand, the Guarani contribution was clearly detected through the presence of lineages such as #75 (Marreroet al., 2007b). However, most of the Amerindian lineages found in Porto Alegre did not match and/or cluster with Guarani mtDNA sequences. These results support the idea that the present Guarani mitochondrial genome may be a poor representative of that found at colonial times (Marreroet al., 2007a). This finding also suggests that other tribes may have made a more significant contribution, through their women, to the formation of the contemporary admixed Porto Alegre population.

Ancestral contributions

Table 3 summarizes the continental origins of the two Porto Alegre samples based on the mtDNA and Y-chromosome haplogroups. Although there was a significant introduction of non-European mtDNA sequences (Amerindian = 21%; African = 10%) among whites, Europe was still the major contributor in both genetic systems (mtDNA = 69%; Y-chromosome = 99%). This finding supported the general correspondence between physical appearance and maternal or paternal ancestry at the population level. In contrast, a completely different picture emerged when the black group was considered. Most of the mtDNA sequences (79%) had an African origin, but 56% of the Y-chromosomes were of European origin, while the Amerindian contribution involved both paternal and maternal inheritance.

These results for the black group can be partly explained by the fact thatmulatos andpardos, who showed visible signs of admixture, were included in this sample. However, history and the dynamics of admixture could also have played an important role. In the early centuries of colonization, almost only European men migrated to Brazil, and for different reasons, African males were brought preferentially to Brazil during the slave trade (Mattoso, 1982). This initial demographic asymmetry, and compulsory restrictions to the African male slaves reproduction, determined that the first Brazilians were born mostly from the union between European males and Amerindian or African females. Later, social practices determined that a child with more pronounced physical African features would be considered black, while those with more pronounced European features would be considered white. This situation created ample opportunity for the introduction of African mtDNA lineages and European Y-chromosomes into the white and black segments, respectively (Parraet al., 2003;Gonçalveset al., 2007). A second major European migratory movement during the 19^th century that was particularly important for southern Brazil involved couples and families, not just males. This migration resulted in many white persons/populations with complete European genomes, whereas others are phenotypically white but show non-European admixture signs at the genome level (Marreroet al., 2005;Zembrzuskiet al., 2006).

To investigate whether these differences between the two skin color groups were peculiar to Porto Alegre or whether they represented a more general tendency, we compiled the literature data for all of the estimates of African, European and Amerindian contributions in black and white Brazilian populations from different geographical regions.Table 4 shows that the pattern described above occurs throughout southern Brazil, but not in other regions of the country. In blacks from the Southeast, for example, the African component predominates in both paternal and maternal data sets, whereas among whites in this region the European contribution is particularly frequent when only Y chromosome markers are considered.Table 4 also show that the whites from the North and South present large differences, basically related to the Amerindian and European women contribution; the extensive admixture between Indians and non-Indians ended in southern Brazil at least 170 years ago, whereas in northern Brazil, especially in the Amazon basin, Amerindian genes are still being introduced into non-native urban and rural populations. The results of these discontinuousvs. continuous patterns of gene flow can be seen by comparing the mtDNA results mentioned above with the biparental loci admixture values (21%vs. 54% and 13%vs. 44% for the Amerindian component in white samples from the South and North, respectively). In contrast, groups or populations identified as white in the Northeast and Southeast had very similar proportions of Amerindian, European and African ancestries in all of the genetic systems investigated. Since European colonization started almost simultaneously in the Northeast and Southeast, this similarity suggests that the dynamics of admixture were similar in both regions.

These striking differences between and within the skin color groups in Brazilian regions can be due to several factors, and some can be the same as those presented for the Porto Alegre case. The type of classification employed to classify the samples in the different studies is also important. Both self and interviewer classifications are full of subjectivities (Salzano and Bortolini, 2002). Distinct admixture dynamics due to historical events and social practices should also be considered. Overall, our results corroborate the idea that, despite some general trends, there is a notable heterogeneity in the pattern of admixture within and among populations/groups in Brazil (Bortoliniet al., 1999;Alves-Silvaet al., 2000;Marreroet al., 2005). Our findings also highlight the intricacies of past and present patterns of mating in a complex society with a relatively recent multiethnic origin, and the relative instability of phenotypic classifications within this society.

1. Abe-Sandes K., Silva W., Jr, Zago M.A. Heterogeneity of the Y chromosome in Afro-Brazilian populations. Hum Biol. 2004;76:77–86. doi: 10.1353/hub.2004.0014. [DOI] [PubMed] [Google Scholar]
2. Alves-Silva J., Santos M.S., Guimarães P.M., Ferreira A.C.S., Bandelt H.-.J., Pena S.D.J., Prado V.F. The ancestry of Brazilian mtDNA lineages. Am J Hum Genet. 2000;67:444–461. doi: 10.1086/303004. [DOI] [PMC free article] [PubMed] [Google Scholar]
3. Andrews R.M., Kubacka I., Chinnery P.F., Lightowlers R.N., Turnbull D.M., Howell N. Reanalysis and revision of the Cambridge reference sequence for human mitochondrial DNA. Nat Genet. 1999;23:147. doi: 10.1038/13779. [DOI] [PubMed] [Google Scholar]
4. Bandelt H.J., Forster P., Rohl A. Median-joining networks for inferring intraspecific phylogenies. Mol Biol Evol. 1999;16:37–48. doi: 10.1093/oxfordjournals.molbev.a026036. [DOI] [PubMed] [Google Scholar]
5. Bandelt H.J., Quintana-Murci L., Salas A., Macaulay V. The fingerprint of phantom mutations in mitochondrial DNA data. Am J Hum Genet. 2002;71:1150–1160. doi: 10.1086/344397. [DOI] [PMC free article] [PubMed] [Google Scholar]
6. Beleza S., Gusmão L., Amorim A., Carracedo A., Salas A. The genetic legacy of western Bantu migrations. Hum Genet. 2005;117:366–375. doi: 10.1007/s00439-005-1290-3. [DOI] [PubMed] [Google Scholar]
7. Beleza S., Gusmão L., Lopes A., Alves C., Gomes I., Giouzeli M., Calafell F., Carracedo A., Amorim A. Micro-phylogeographic and demographic history of Portuguese male lineages. Ann Hum Genet. 2006;70:181–194. doi: 10.1111/j.1529-8817.2005.00221.x. [DOI] [PubMed] [Google Scholar]
8. Bortolini M.C., Zago M.A., Salzano F.M., Siva W.A., Jr, Bonatto W.A., Silva M.C., Weimer T.A. Evolutionary and anthropological implications of mitochondrial DNA variation in African Brazilian populations. Hum Biol. 1997;69:141–159. [PubMed] [Google Scholar]
9. Bortolini M.C., Silva W.A., Junior, Castro-de-Guerra D., Remonatto G., Mirandola R., Hutz M.H., Weimer T.A., Zago M.A., Salzano F.M. African-derived South American populations: A history of symmetrical and asymmetrical matings according to sex revealed by bi and uniparental genetic markers. Am J Hum Biol. 1999;11:551–563. doi: 10.1002/(SICI)1520-6300(1999)11:4<551::AID-AJHB15>3.0.CO;2-Z. [DOI] [PubMed] [Google Scholar]
10. Bortolini M.C., Salzano F.M., Thomas M.G., Nasanem S.P.K., Bau C.H.D., Hutz M.H., Layrisse Z., Petz-Erler M.L., Tsuneto L.T., Hill K., et al. Y chromosome evidence for differing ancient demographic histories in the Americas. Am J Hum Genet. 2003;73:524–539. doi: 10.1086/377588. [DOI] [PMC free article] [PubMed] [Google Scholar]
11. Brehm A., Pereira L., Kivisild T., Amorim A. Mitochondrial portraits of the Madeira and Acores archipelagos witness different genetic pools of its settlers. Hum Genet. 2003;114:77–86. doi: 10.1007/s00439-003-1024-3. [DOI] [PubMed] [Google Scholar]
12. Callegari-Jacques S.M., Grattapaglia D., Salzano F.M., Salamoni S.P., Crossetti S.G., Ferreira M.E., Hutz M.H. Historical genetics: Spatiotemporal analysis of the formation of the Brazilian population. Am J Hum Biol. 2003;15:824–834. doi: 10.1002/ajhb.10217. [DOI] [PubMed] [Google Scholar]
13. Capelli C., Brisighelli F., Scarnicci F., Arredi B., Caglia A., Vetrugno G., Tofanelli S., Onofri V., Tagliabracci A., Paoli G., et al. Y chromosome genetic variation in the Italian peninsula is clinal and supports an admixture model for the Mesolithic-Neolithic encounter. Mol Phylogenet Evol. 2007;44:228–239. doi: 10.1016/j.ympev.2006.11.030. [DOI] [PubMed] [Google Scholar]
14. Capelli C., Redhead N., Romano V., Cali F., Lefranc G., Delaque V., Megarbane A., Felice A.E., Pascali V.L., Neophytou P.I., et al. Population structure in the Mediterranean basin: A Y chromosome perpective. Ann Hum Genet. 2006;70:207–225. doi: 10.1111/j.1529-8817.2005.00224.x. [DOI] [PubMed] [Google Scholar]
15. Carvalho-Silva D.R., Santos F.R., Rocha J., Pena S.D. The phylogeography of Brazilian Y-chromosome lineages. Am J Hum Genet. 2001;68:281–286. doi: 10.1086/316931. [DOI] [PMC free article] [PubMed] [Google Scholar]
16. Coia V., Destro-Bisol G., Verginelli F., Battaggia C., Boschi I., Cruciani F., Spedini G., Comas D., Calafell F. mtDNA variation in North Cameroon: Lack of Asian lineages and implications for back migration from Asia to sub-Saharan Africa. Am J Phys Anthropol. 2005;128:678–681. doi: 10.1002/ajpa.20138. [DOI] [PubMed] [Google Scholar]
17. Crespillo M., Luque J.A., Paredes M., Fernandez R., Ramirez E., Valverde J.L. Mitochondrial DNA sequences for 118 individuals from northeastern Spain. Int J Legal Med. 2000;114:130–132. doi: 10.1007/s004140000158. [DOI] [PubMed] [Google Scholar]
18. Excoffier L., Laval G.L., Schneider S. Arlequin v. 3.0: An integrated software package for population genetics data analysis. Evol Bioinform Online. 2005;1:47–50. [PMC free article] [PubMed] [Google Scholar]
19. Flores C., Maca-Meyer N., Perez J.A., Gonzalez A.M., Larruga J.M., Cabrera V.M. A predominant European ancestry of paternal lineages from Canary Islanders. Ann Hum Genet. 2003;67:138–152. doi: 10.1046/j.1469-1809.2003.00015.x. [DOI] [PubMed] [Google Scholar]
20. Flores M. História do Rio Grande do Sul. 5th edition. Porto Alegre: Nova Dimensão; 1996. [Google Scholar]
21. Gonçalves R., Freitas A., Branco M., Rosa A., Fernandes A.T., Zhivotovsky L.A., Underhill P.A., Kivisild T., Brehm A. Y-chromosome lineages from Portugal, Madeira and Açores record elements of Sephardim and Berber ancestry. Ann Hum Genet. 2005;69:443–454. doi: 10.1111/j.1529-8817.2005.00161.x. [DOI] [PubMed] [Google Scholar]
22. Gonçalves V.F., Prosdocimi F., Santos L.S., Ortega J.M., Pena S.D.J. Sex-biased gene flow in African Americans but not in American Caucasians. Genet Mol Res. 2007;6:256–261. [PubMed] [Google Scholar]
23. Gonçalves V.F., Carvalho C.M., Bortolini M.C., Bydlowski S.P., Pena S.D. The phylogeography of African Brazilians. Hum Hered. 2008;65:23–32. doi: 10.1159/000106059. [DOI] [PubMed] [Google Scholar]
24. Hall T.A. BioEdit: A user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symp Ser. 1999;41:95–98. [Google Scholar]
25. Hammer M.F., Horai S. Y chromosomal DNA variation and the peopling of Japan. Am J Hum Genet. 1995;56:951–962. [PMC free article] [PubMed] [Google Scholar]
26. Hünemeier T., Carvalho C., Marrero A.R., Salzano F.M., Pena S.D.J., Bortolini M.C. Niger-Congo speaking populations and the formation of the Brazilian gene pool: mtDNA and Y-chromosome data. Am J Phys Anthropol. 2007;133:854–867. doi: 10.1002/ajpa.20604. [DOI] [PubMed] [Google Scholar]
27. Hurles M.E., Veitia R., Arroyo E., Armenteros M., Bertranpetit J., Pérez-Lezaun A., Bosch E., Shlumukova M., Cambon-Thomsen A., Mcelreavey K., et al. Recent male mediated gene flow over a linguistic barrier in Iberia, suggested by analyses of a Y-chromosomal DNA polymorphism. Am J Hum Genet. 1999;65:1437–1448. doi: 10.1086/302617. [DOI] [PMC free article] [PubMed] [Google Scholar]
28. Jackson B.A., Wilson J.L., Kirbah S., Sidney S.S., Rosenberg J., Bassie N., Alie J.A., McLean D.C., Garvey W.T., Ely B. Mitochondrial DNA genetic diversity among four ethnic groups in Sierra Leone. Am J Phys Anthropol. 2005;128:156–163. doi: 10.1002/ajpa.20040. [DOI] [PubMed] [Google Scholar]
29. Jobling M.A., Tyler-Smith C. The human Y chromosome: An evolutionary marker comes of age. Nat Rev Genet. 2003;4:598–612. doi: 10.1038/nrg1124. [DOI] [PubMed] [Google Scholar]
30. Kayser M., Lao O., Anslinger K., Augustin C., Barge L.G., Edelmann J., Elias S., Heinrich M., Henke J., Henke L., et al. Sex-biased gene flow in African Americans but not in American Caucasians. Genet Mol Res. 2007;6:256–261. [PubMed] [Google Scholar]
31. Kivisild T., Tolk H.V., Parik J., Wang Y., Papiha S.S., Bandelt H.J., Gonçalves V.F., Prosdocimi F., Santos L.S., Ortega J.M., et al. Sex-biased gene flow in African Americans but not in American Caucasians. Genet Mol Res. 2007;6:256–261. [PubMed] [Google Scholar]
32. Lahiri D.K., Nurnberger J.I. A rapid non-enzymatic method for preparation of HMW DNA from blood for RFLP studies. Nucleic Acids Res. 1991;19:5444. doi: 10.1093/nar/19.19.5444. [DOI] [PMC free article] [PubMed] [Google Scholar]
33. Laytano D. Legado Luso-Açoriano na Formação do Rio Grande do Sul. Porto Alegre: Centro Regional de Pesquisas Educacionais; 1974. [Google Scholar]
34. Marrero A.R., Leite F.P.N., Carvalho B.A., Peres L.M., Kommers T.C., Cruz I.M., Salzano F.M., Linares A.R., Silva W.A., Jr, Bortolini M.C. Heterogeneity of the genome ancestry of individuals classified as white in the state of Rio Grande do Sul, Brazil. Am J Hum Biol. 2005;17:496–506. doi: 10.1002/ajhb.20404. [DOI] [PubMed] [Google Scholar]
35. Marrero A.R., Bravi C., Stuart S., Long J.C., Leite F.P.N., Kommers T., Carvalho C.M.B., Pena S.D.J., Ruiz-Linares A., Salzano F.M., et al. Pre and post-Columbian gene and cultural identity: The case of the Gaucho from southern Brazil. Hum Hered. 2007a;64:160–171. doi: 10.1159/000102989. [DOI] [PubMed] [Google Scholar]
36. Marrero A.R., Silva-Junior W.A., Bravi C.M., Hutz M.H., Petzl-Erler M.L., Ruiz-Linares A., Salzano F.M., Bortolini M.C. The demographic and evolutionary trajectories of the Guarani and Kaingang natives of Brazil. Am J Phys Anthropol. 2007b;132:301–310. doi: 10.1002/ajpa.20515. [DOI] [PubMed] [Google Scholar]
37. Mattoso K.M.Q. Ser Escravo no Brasil. São Paulo: Editora Brasiliense; 1982. [Google Scholar]
38. Mogentale-Profizi N., Chollet L., Stevanovitch A., Dubut V., Poggi C., Pradie M.P., Spadoni J.L., Gilles A., Beraud-Colomb E. Mitochondrial DNA sequence diversity in two groups of Italian Veneto speakers from Veneto. Ann Hum Genet. 2001;65:153–166. doi: 10.1017/S0003480001008545. [DOI] [PubMed] [Google Scholar]
39. Montiel R., Bettencourt C., Silva C., Santos C., Prata M.J., Lima M. Analysis of Y-chromosome variability and its comparison with mtDNA variability reveals different demographic histories between islands in the Azores Archipelago (Portugal) Ann Hum Genet. 2005;69:135–144. doi: 10.1046/j.1529-8817.2004.00146.x. [DOI] [PubMed] [Google Scholar]
40. Noelli F.S., Silva S.A., Vietta K., Tocchetto F.B., Cappelletti A., Da Costa J.F.G., Soares A.L.R., Marques K.J. O mapa arqueológico parcial e a revisão historiográfica a respeito das ocupações indígenas pré-históricas no município de Porto Alegre, Rio Grande do Sul. Rev Hist Regional. 1997;2:209–221. [Google Scholar]
41. Nogueról L.P.F. Preços de bois cavalos e escravos em Porto Alegre e em Sambará, no século XIX: Mercadorias de um mercado nacional em formação. Ensaios FEE. 2005;26:7–36. [Google Scholar]
42. Parra F.C., Amado R.C., Lambertucci J.R., Rocha J., Antunes C.M., Pena S.D. Color and genomic ancestry in Brazilians. Proc Natl Acad Sci USA. 2003;100:177–182. doi: 10.1073/pnas.0126614100. [DOI] [PMC free article] [PubMed] [Google Scholar]
43. Pereira L., Prata M.J., Amorim A. Diversity of mtDNA lineages in Portugal: Not a genetic edge of European variation. Ann Hum Genet. 2000;64:491–506. doi: 10.1046/j.1469-1809.2000.6460491.x. [DOI] [PubMed] [Google Scholar]
44. Pichler I., Mueller J.C., Stefanov S.A., De Grandi A., Volpato C.B., Pinggera G.K., Mayr A., Ogriseg M., Ploner F., Meitinger T., et al. Genetic structure in contemporary south Tyrolean isolated populations revealed by analysis of Y-chromosome, mtDNA, and Alu polymorphisms. Hum Biol. 2006;78:441–464. doi: 10.1353/hub.2006.0057. [DOI] [PubMed] [Google Scholar]
45. Picornell A., Gomez-Barbeito L., Tomas C., Castro J.A., Ramon M.M. Mitochondrial DNA HVRI variation in Balearic populations. Am J Phys Anthropol. 2005;128:119–130. doi: 10.1002/ajpa.10423. [DOI] [PubMed] [Google Scholar]
46. Plaza S., Salas A., Calafell F., Corte-Real F., Bertranpetit J., Carracedo A., Comas D. Insights into the western Bantu dispersal: mtDNA lineage analysis in Angola. Hum Genet. 2004;115:439–447. doi: 10.1007/s00439-004-1164-0. [DOI] [PubMed] [Google Scholar]
47. Ploski R. Significant genetic differentiation between Poland and Germany follows present-day political borders, as revealed by Y-chromosome analysis. Hum Genet. 2005;117:428–443. doi: 10.1007/s00439-005-1333-9. [DOI] [PubMed] [Google Scholar]
48. Poetsch M., Wittig H., Krause D., Lignitz E. Mitochondrial diversity of a northeast German population sample. Forensic Sci Int. 2003;137:125–132. doi: 10.1016/j.forsciint.2003.06.001. [DOI] [PubMed] [Google Scholar]
49. Ribeiro-dos-Santos A.K., Carvalho B.M., Feio-dos-Santos A.C., Santos S.E.B. Nucleotide variability of HV-I in Afro-descendent populations of the Brazilian Amazon region. Forensic Sci Int. 2006;167:77–80. doi: 10.1016/j.forsciint.2005.12.033. [DOI] [PubMed] [Google Scholar]
50. Rosa A., Brehm A., Kivisild T., Metspalu E., Villems R. MtDNA profile of West Africa Guineans: Towards a better understanding of the Senegambia region. Ann Hum Genet. 2004;68:340–352. doi: 10.1046/j.1529-8817.2004.00100.x. [DOI] [PubMed] [Google Scholar]
51. Rosser Z.H., Zerjal T., Hurles M.E., Adojaan M., Alavantic D., Amorim A., Amos W., Armenteros M., Arroyo E., Barbujani G., et al. Y-chromosomal diversity in Europe is clinal and influenced primarily by geography, rather than by language. Am J Hum Genet. 2000;67:1526–1543. doi: 10.1086/316890. [DOI] [PMC free article] [PubMed] [Google Scholar]
52. Salas A., Richards M., De la Fe T., Lareu M.V., Sobrino B., Sanchez-Diz P., Macaulay V., Carracedo A. The making of the African mtDNA landscape. Am J Hum Genet. 2002;71:1082–1111. doi: 10.1086/344348. [DOI] [PMC free article] [PubMed] [Google Scholar]
53. Salas A., Richards M., Lareu M.V., Scozzari R., Coppa A., Torroni A., Macaulay V., Carracedo A. The African diaspora: Mitochondrial DNA and the Atlantic slave trade. Am J Hum Genet. 2004;74:454–465. doi: 10.1086/382194. [DOI] [PMC free article] [PubMed] [Google Scholar]
54. Salzano F.M., Bortolini M.C. The Evolution and Genetics of Latin American Populations. Cambridge: Cambridge University Press; 2002. [Google Scholar]
55. Schneider S., Roessli D., Excoffier L. Arlequin v. 2.000: A software for population genetic analysis. University of Geneva: Genetics and Biometry Laboratory; 2000. [Google Scholar]
56. Silva D.A., Carvalho E., Costa G., Tavares L., Amorim A., Gusmão L. Y-chromosome genetic variation in Rio de Janeiro population. Am J Hum Biol. 2006;18:829–837. doi: 10.1002/ajhb.20567. [DOI] [PubMed] [Google Scholar]
57. Silva-Junior W.A., Bortolini M.C., Schneider M.P.C., Marrero A., Elion J., Krishnamoorthy R., Zago M.A. mtDNA haplogroup analysis of black and sub-Saharan populations: Implications for the Atlantic slave trade. Hum Biol. 2006;78:29–41. doi: 10.1353/hub.2006.0028. [DOI] [PubMed] [Google Scholar]
58. Thomas M.G., Bradman N., Flinn H.M. High throughput analysis of 10 microsatellites and 11 di-allelic polymorphisms on the human Y-chromosome. Hum Genet. 1999;105:577–581. doi: 10.1007/s004399900181. [DOI] [PubMed] [Google Scholar]
59. Torroni A., Achilli A., Macaulay V., Richards M., Bandelt H.J. Harvesting the fruit of the human mtDNA tree. Trends Genet. 2006;22:339–345. doi: 10.1016/j.tig.2006.04.001. [DOI] [PubMed] [Google Scholar]
60. Underhill P., Jin L., Zemans R., Oefner P.J., Cavalli-Sforza L.L. A pre-Columbian Y chromosome-specific transition and its implications for human evolutionary history. Proc Natl Acad Sci USA. 1996;93:196–200. doi: 10.1073/pnas.93.1.196. [DOI] [PMC free article] [PubMed] [Google Scholar]
61. Underhill P.A., Passarino G., Lin A.A., Shen P., Mirazon Lahr M., Oefner P.J., Foley R.A., Cavalli-Sforza L.L. The phylogeography of Y chromosome binary haplotypes andthe origins of modern human populations. Ann Hum Genet. 2001;65:43–62. doi: 10.1046/j.1469-1809.2001.6510043.x. [DOI] [PubMed] [Google Scholar]
62. Villems R. The emerging limbs and twigs of the East Asian mtDNA tree. Mol Biol Evol. 2002;19:1737–1751. doi: 10.1093/oxfordjournals.molbev.a003996. [DOI] [PubMed] [Google Scholar]
63. Yao Y.G., Bravi C.M., Bandelt H.-.J. A call for mtDNA data quality control in forensic science. Forensic Sci Int. 2004;141:1–6. doi: 10.1016/j.forsciint.2003.12.004. [DOI] [PubMed] [Google Scholar]
64. Zembrzuski V.M., Callegari-Jacques S.M., Hutz M.H. Application of an African Ancestry Index as a genomic control approach in a Brazilian population. Ann Hum Genet. 2006;70:822–828. doi: 10.1111/j.1469-1809.2006.00270.x. [DOI] [PubMed] [Google Scholar]

1. Arlequin: A software for population genetics data analysis. Available from:http://lgb.unige.ch/arlequin/
2. Bioedit: Biological sequence alignment editor for Windows. [May 12, 2007]. Available from:http://www.mbio.ncsu.edu/BioEdit/bioedit.html.
3. Chromas Lite 2.0 Program. [May 15, 2007]. Available from:http://www.technelsyum.com.au.
4. Instituto Brasileiro de Estatistica e Geografia (IBGE) [October 5, 2007]. Available from:http://www.ibge.gov.br/home/estatistica/populacao/censo2000/populacao/censo2000_populacao.pdf.
5. Network 4.2.0.0 Program. [May 29, 2007]. Available from:http://www.fluxus-engineering.com.