One hundred nineteen individuals classified as White, living in different localities of the Brazilian state of Rio Grande do Sul, were studied in relation to the HVS-I region of the mitochondrial DNA (mtDNA). The male fraction of the sample (N = 74) was also tested for seven Y-chromosome polymorphisms. In a specific population (Veranópolis), a city characterized by a large influence of the Italian immigration of the 19th century, the results from the maternal and paternal sides indicated almost complete European ancestry. However, another sample identified as White, from different localities of Rio Grande do Sul, presented significant fractions of Native American (36%) and African (16%) mtDNA haplogroups. These results indicate that Brazilian populations are remarkably heterogeneous; while some present an overwhelming majority of transplanted European genomes, with a complete correspondence between physical appearance and ancestry, others reflect a history of extensive admixture with dissociation between physical appearance and ancestry.

Objective: To investigate the evolutionary and demographic history of the Gaucho, a distinct population of southern Brazil, relating it to their culture, to assess possible parallel continuity. Methods: Six binary polymorphisms, an Alu insertion polymorphism (YAP) and 12 short tandem repeat loci in the non-recombining region of the Y-chromosome, as well as the sequence of the first hypervariable segment (HVS-I) of the mitochondrial DNA (mtDNA) control region were studied in 150 unrelated males born in the Pampa region of Rio Grande do Sul. Results: Comparison of the results with the other Brazilian and Uruguayan populations, as well as with their putative ancestors, indicated a stronger male Spanish influence than that observed elsewhere in Brazil, a former Portuguese colony. Extensive mtDNA analyses of their Amerindian component gave clear indications of the presence there of material from extinct (Charrua), as well as extant (Guarani) tribes. Conclusions: The genetic analyses contributed in a significant way to reveal that the known cultural continuity between pre- and post-Columbian Pampa populations was also accompanied by an extraordinary genetic continuity.

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