Y Chromosome Lineages in Men of West African Descent

The early African experience in the Americas is marked by the transatlantic slave trade from ∼1619 to 1850 and the rise of the plantation system. The origins of enslaved Africans were largely dependent on European preferences as well as the availability of potential laborers within Africa. Rice production was a key industry of many colonial South Carolina low country plantations. Accordingly, rice plantations owners within South Carolina often requested enslaved Africans from the so-called “Grain Coast” of western Africa (Senegal to Sierra Leone). Studies on the African origins of the enslaved within other regions of the Americas have been limited. To address the issue of origins of people of African descent within the Americas and understand more about the genetic heterogeneity present within Africa and the African Diaspora, we typed Y chromosome specific markers in 1,319 men consisting of 508 west and central Africans (from 12 populations), 188 Caribbeans (from 2 islands), 532 African Americans (AAs from Washington, DC and Columbia, SC), and 91 European Americans. Principal component and admixture analyses provide support for significant Grain Coast ancestry among African American men in South Carolina. AA men from DC and the Caribbean showed a closer affinity to populations from the Bight of Biafra. Furthermore, 30–40% of the paternal lineages in African descent populations in the Americas are of European ancestry. Diverse west African ancestries and sex-biased gene flow from EAs has contributed greatly to the genetic heterogeneity of African populations throughout the Americas and has significant implications for gene mapping efforts in these populations

Y Chromosome Lineages in Men of West African Descent

The early African experience in the Americas is marked by the transatlantic slave trade from ~1619 to 1850 and the rise of the plantation system. The origins of enslaved Africans were largely dependent on European preferences as well as the availability of potential laborers within Africa. Rice production was a key industry of many colonial South Carolina low country plantations. Accordingly, rice plantations owners within South Carolina often requested enslaved Africans from the so-called ‘‘Grain Coast’’ of western Africa (Senegal to Sierra Leone). Studies on the African origins of the enslaved within other regions of the Americas have been limited. To address the issue of origins of people of African descent within the Americas and understand more about the genetic heterogeneity present within Africa and the African Diaspora, we typed Y chromosome specific markers in 1,319 men consisting of 508 west and central Africans (from 12 populations), 188 Caribbeans (from 2 islands), 532 African Americans (AAs from Washington, DC and Columbia, SC), and 91 European Americans. Principal component and admixture analyses provide support for significant Grain Coast ancestry among African American men in South Carolina. AA men fromDC and the Caribbean showed a closer affinity to populations from the Bight of Biafra. Furthermore, 30–40% of the paternal lineages in African descent populations in the Americas are of European ancestry. Diverse west African ancestries and sexbiased gene flow from EAs has contributed greatly to the genetic heterogeneity of African populations throughout the Americas and has significant implications for gene mapping efforts in these populations

Estimates of European paternal ancestry (%) in African descent populations in the Americas.

<p>Estimates of European paternal ancestry (%) in African descent populations in the Americas.</p

Partitions of Y chromosome molecular variance.

<p> <b>Φ_ST = Within populations; Φ_CT = Among groups; Φ_SC = Among populations within groups; %V = Percent of the variance.</b></p

Expansion Times of West African Y Chromosome Groups.

<p>Expansion Times of West African Y Chromosome Groups.</p

Plot of the first two principal components of a Y chromosome genetic distance matrix estimated for 17 populations.

<p>Plot of the first two principal components of a Y chromosome genetic distance matrix estimated for 17 populations.</p

Summary of Y chromosome diversity and frequency of YAP and M89 alleles.

<p><b>Note</b>. n = number of Y-chromosomes, <i>k</i> = observed number of haplotypes, H = haplotype diversity, <i>h</i> = allelic diversity, MPD = mean pairwise differences of haplotypes.</p

Maps showing location of (A) 5 populations in the Americas and (B) 12 West African populations sampled in the study.

<p>Maps showing location of (A) 5 populations in the Americas and (B) 12 West African populations sampled in the study.</p