Ancestralidade genômica e dinâmica de miscigenação: estimativas e aspectos computacionais

Abstract

Due to European colonization and the trafficking of enslaved people, admixture in the Americas is a defining characteristic of its populations that extends beyond historical context. This process is also imprinted in the genomes of American individuals, allowing us to retrieve information about the history of admixture through genetic data. Genetic ancestry can be inferred at three levels: population-level (classical approach), where the proportion of contribution from each parental population to the admixed population is estimated; individual-level, where the proportion of each parental population's contribution to an individual's genome is inferred; and local or chromosomal-level, made possible by the recent availability of high-density genomic data, where the ancestry of each fragment of each chromosome in an admixed individual can be determined. Statistically, the size of an ancestry segment is expected to be inversely proportional to the time elapsed since the admixture event introduced it into the population: the older the event, the smaller the fragment (and vice versa). Based on this concept, our group developed a method using Approximate Bayesian Computation to infer the posterior distributions of nine parameters representing the contributions of European, African, and Native American ancestral populations in three admixture pulses that occurred over 500 years of admixture in the Americas (Kehdy et al. 2015). This project aims to infer and analyze the ancestry of Latin American individuals in the context of collaborative projects, along with validating the method developed by our group, which seeks to infer the dynamics of the admixture process through population genetics studies, reconstructing the genetic history of how interactions between parental populations occurred and its validation