1Department of Genetics, Federal University of Rio Grande do Sul, 2Molecular Biology Division, Allevo Genetics, 3Faculty of Biosciences, Pontifical Catholic University of Rio Grande do Sul
Friday 4:00-4:15, Grand Ballroom II
Recent evolutionary models for the peopling of the Americas have emphasizing the role of recent (Holocenic) gene flow with Asian populations. A recent work used Approximate Bayesian Computation and a large dataset of ~400 STR markers typed in 30 Native American and Asian populations found that a scenario with recurrent gene flow between populations from the two continents during the Holocene received strong posterior support. A better characterization of the size of the original founder population for the peopling of the Americas may be important to access the level of genetic and morphologic variation harbored by these initial settlers. However, because the presence and strength of gene flow may affect estimates of the initial population size for the peopling of the Americas we aim at estimating the size of such founder population using 9 intergenic autosomal loci irrespective of the level of gene flow. DNA samples from ten Native American individuals, eight Siberians were used together with information from 15 Han Chinese individuals available from the literature. Genetic data for these individuals were used in an Isolation-with-Migration scenario with or without gene flow in the program IM. Our results suggest that the original Native American founder population had between ~75 and ~4,850 individuals, even though the most likely numbers are around 200 individuals. This implies in a moderate to strong bottleneck which is consistent with estimates from other genetic markers. This estimate may be useful to understand how variable in morphology the initial settlers might have been.
This study was funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), grants number 477780/2003-2, and151263/2007-8.