RESUMO
Recent studies of the Uruguayan population revealed different amounts of Amerindian and African genetic contributions. Our previous analysis of Afro-Uruguayans from the capital city of the Department of Cerro Largo showed a high proportion of African genes, and the effects of directional mating involving Amerindian women. In this paper, we extended the analysis to a sample of more than 100 individuals representing a random sample of the population of the whole Department. Based on 18 autosomal markers and one X-linked marker, we estimated 82% European, 8% Amerindian, and 10% African contributions to their ancestry, while from seven mitochondrial DNA site-specific polymorphic markers and sequences of hypervariable segment I, we determined 49% European, 30% Amerindian, and 21% African maternal contributions. Directional matings between Amerindian women and European men were detected, but differences involving Africans were not significant. Data about the specific origins of maternal lineages were also provided, and placed in a historical context.
Assuntos
Antígenos de Grupos Sanguíneos/classificação , Cromossomos Humanos Y/genética , DNA Mitocondrial/genética , Genética Populacional , Polimorfismo Genético , População Negra/etnologia , População Negra/genética , Antígenos de Grupos Sanguíneos/sangue , Cromossomos Humanos Y/classificação , DNA Mitocondrial/classificação , Demografia , Emigração e Imigração , Frequência do Gene/genética , Genótipo , Haplótipos/genética , Humanos , Indígenas Sul-Americanos/etnologia , Indígenas Sul-Americanos/genética , Fenótipo , Filogenia , Análise de Sequência de DNA , Uruguai/etnologia , População Branca/etnologia , População Branca/genéticaRESUMO
In admixed populations, genetic contributions from males and females of specific parental populations can be of different proportions due to past directional mating during the process of genetic admixture. In this research paper, we provide evidence of such male- and female-specific differential admixture components of African, European, and American Indian origin in an admixed population from the city of Melo, in the northeastern region of Uruguay. From data on 11 autosomal markers from a sample of 41 individuals of mixed African descent, we estimated 47% African, 38% European, and 15% Amerindian contributions. In contrast, 6 mtDNA site-specific polymorphic markers showed that the mtDNA genome of these individuals was 52% African, 19% European, and 29% Amerindian, while from 3 Y-specific polymorphic sites, we estimated 30% African, 64% European, and 6% Amerindian contributions. We argue that this heterogeneity of admixture estimates results from disproportionate unions of European males with African and American Indian females from which this mixed African population was formed. Also, we argue that the asymmetry of the admixture estimates from the three sets of markers (autosomal, mtDNA, and Y-linked) is a result of the changes in the direction of mating during the history of the population. Implications of such evidence of directional mating are discussed, indicating the need of further demographic data for a quantitative assessment of the impact of directional mating on genetic structure of admixed populations.
Assuntos
DNA Mitocondrial/genética , Marcadores Genéticos , Genética Populacional , Indígenas Norte-Americanos , Cromossomo Y/genética , África/etnologia , Demografia , Europa (Continente)/etnologia , Feminino , Humanos , Masculino , Reprodução , Uruguai/epidemiologiaRESUMO
Os plasmas de um total de 488 indivíduos pertencentes a cinco populaçöes indígenas sul-americanas foram investigados, por meio de isoeletrofocalizaçäo, quanto ao sistema GC, e os resultados obtidos foram comparados aos descritos para onze outras tribos ameríndias. A um nível de 0,15 dissimilaridade genética foram observados quatro agrupamentos, näo tendo sido detectada uma associaçäo clara entre as freqüências alélicas neste sistema e a quantidade de radiaçäo solar
