Reconstructing the Genetic History of the Atlantic Slave Trade Using Genomic Data from the Nigerian Diaspora and West African Populations

The transatlantic slave trade displaced millions of individuals from West and Central Africa to the Americas between the 16th and 19th centuries, leaving a complex genetic legacy in diaspora populations. Genomic analyses of admixed African-descendant populations in the Americas, combined with reference data from West African source populations, can reconstruct ancestry contributions and infer historical forced migration routes. Nigerian populations, given the heavy historical slave trade through ports along the Bight of Benin and Bight of Biafra, are critical reference populations for diaspora genomic reconstruction. This dissertation employed whole genome sequencing data from 800 Nigerians across Yoruba, Igbo, Edo, Efik, and Ibibio ethnic groups, alongside published genome data from African-descendant populations in Brazil, the United States, Cuba, and Jamaica. Local ancestry deconvolution was performed using RFMix, and Nigerian ethnic group ancestry contributions to diaspora populations were quantified. Approximate Bayesian computation was applied to model demographic history and estimate divergence times from source populations. The Yoruba were the predominant West African ancestral source for the studied diaspora populations, but Igbo, Edo, and Cross River populations contributed significantly to specific diaspora communities. These findings advance the historical genetics of the Atlantic slave trade and have profound implications for diaspora identity and heritage. Keywords: Atlantic slave trade, diaspora genomics, Yoruba, local ancestry, population history