Detecting Sex-Biased Gene Flow in African-Americans through the Analysis of Intra- and Inter-Population Variation at Mitochondrial DNA and Y- Chromosome Microsatellites

Evolutionary perspectives on African North American genetic diversity: Origins and prospects for future investigations

African-descended peoples of the Americas represent an amalgamation of West, Central, and Southeast African regional and ethnic groups with modest gene flow from specific non-African populations. Despite 16+ generations of residence in the Americas, there is a deficit of evolutionary knowledge about these populations. Focusing on Legacy African American, the African North American descendants of survivors of the transatlantic trade in enslaved Africans, we report on emic evolutionary perspectives of their self-identity gleaned from our interviews of 600 individuals collected over 2 years. Gullah-Geechee peoples of Carolina Coastal regions are a model case study due to their historical antiquity, substantial African retentions, relative geospatial isolation, and proposed progenitor status to other Legacy African American microethnic groups. We identify salient research questions for future studies that will begin to bridge the evolutionary gaps in our knowledge of these diverse peoples and the historical evidence for specific evolutionary processes.

A continuum of admixture in the Western Hemisphere revealed by the African Diaspora genome

The African Diaspora in the Western Hemisphere represents one of the largest forced migrations in history and had a profound impact on genetic diversity in modern populations. To date, the fine-scale population structure of descendants of the African Diaspora remains largely uncharacterized. Here we present genetic variation from deeply sequenced genomes of 642 individuals from North and South American, Caribbean and West African populations, substantially increasing the lexicon of human genomic variation and suggesting much variation remains to be discovered in African-admixed populations in the Americas. We summarize genetic variation in these populations, quantifying the postcolonial sex-biased European gene flow across multiple regions. Moreover, we refine estimates on the burden of deleterious variants carried across populations and how this varies with African ancestry. Our data are an important resource for empowering disease mapping studies in African-admixed individuals and will facilitate gene discovery for diseases disproportionately affecting individuals of African ancestry.