Genetic Polymorphisms Of Y-STR Loci In The Population Of West Africa And Gene Flow Across The Atlantic

The triangle slave trade across the Atlantic had profoundly shaped human society.The population was greatly affected by the significant inflow of Africans into America.Meanwhile,Africans were also greatly impacted by the Atlantic slave trade.Such influence especially reflected on both the genetic landscape and human culture.The general history,from African ports,slaves were transported to the Atlantic Islands,then to Europe.Liberians were suggested to be one of the West Africa groups who had gone to the continents of Europe and America.Although there are many sources,including poetry,novels,autobiographies,and tales,that might be used to track this epic exodus,they are either too hazy or conflicting to offer a comprehensive and organized historical evidence.Additionally,their history of returning to Africa was legendary and unique from that of other African nations.Y-STRs(Short tandem repeats on the Y chromosome)are considered essential forensic and population genetic markers for human patrilineal identification and population differentiation studies.For this reason,DNA databases of Y-STRs have been created for many major populations around the world.Nevertheless,the genetical information of one of the African regions,West Africa,is still poorly characterized(especially Y-STRs).The genetic landscape in West Africa is particularly complex.Y-chromosomal studies are important to depict the phylogeographic finely and the migration route of the slaves’trade of African.The Liberia-population in West Africa,which is vital to reveal the history of the slaves’trade,are far from uncovered for its Y-chromosomal variation.In order to reveal the triangle slave trade’s genetic landscape and to correctly depict the route of the population of West Africa.First,a former developed 41 Y-STR Kit and a new developed Y-comp Y-STR Kit were used for genotyping.This research produced 59 Y-chromosome STR allele frequency data sets for 10 Liberia subpopulations.The output had provided a thorough understanding the population genetic diversity of Liberian.Second,A meta-analysis of already published samples was an aid to further characterize the Y-chromosomal landscape in this region.Several African-descended populations(n=58)were also involved in the further investigating of gene flow and male lineage landscape of transatlantic.Using the Y-STR tool throughout the investigation,this study makes apparent linkages between the people of Liberian and other African ethnic groups as well as other countries.The migration study also included population flows(gene flows)among individuals of African ancestry from Liberia,nearby nations,Europe,Latin America,and the United States.Finally,Liberians’ migration route and model were uncovered.The first two dominant haplogroups were Elbla and Elblb in the Liberia population.Among the four West Africa populations,Nigeria,Burkina Faso,Ghana,and Benin,the recombined KKMG group(Kru,Krahn,Mende,and Gola)showed different migration model with them.The dominant Burkina Faso→KKMG and Nigeria→KKMG revealed the gene flow to Liberia,but emigration of some Liberia subgroups was impressive which were proved be the dominant KKMG→Benin pattern.The best pattern of KKMG(?)Ghana significantly told a different "story" that a bidirectional gene flow may existed throughout the history of the countries.Notably,genetic landscape of Bassa was greatly influenced by the population movements of Burkina Faso and Nigeria.On the contrary,the direction of the population movements of Bassa was mainly towards Benin,while the population movements between Bassa and Ghana were bidirectional.For the two recombined Liberia groups,one included Gbandi,Kpelle,Lorma,and Mano,the other group included Gio and Mende,bidirectional migration patterns were found with Burkina Faso populations.Furthermore,the gene flow of the population of Liberia was investigated in two directions.For the northward and westward routes,hypothesis of Liberian’s final migration to UK or US was studied in seven models.The bidirectional migration pattern of Liberia(?)UK was proved to be the most probable migration model.Hence,rather than going round America,the Liberia population went straight to England directly.Moreover,these movements were bidirectional.Moreover,the migration pattern of US→Liberia was proved to be the most probable migration model.Hence,rather than going round Europe or Latin America,the Liberia population went straight to US directly.In addition,the major movement from US to Liberia proved the historical re-migration wave well.Through this study,we not only understand the genetic structure of West Africa,provide a genetic objective basis for migration research,but also contribute to the in-depth study of the geographical origin and reverse migration history of Liberians.