Binary and microsatellite polymorphisms of the Y‐chromosome in the Mbenzele pygmies from the Central African Republic

Abstract

This study analyzes the variation of six binary polymorphisms and six microsatellites in the Mbenzele Pygmies from the Central African Republic. Five different haplogroups (B2b, E(xE3a), E3a, P and BR(xB2b,DE,P)) were observed, with frequencies ranging from 0.022 (haplogroup P) to 0.609 (haplogroup E3a). A comparison of haplogroup frequencies indicates a close genetic affinity between the Mbenzele and the Biaka Pygmies, a finding consistent with the common origin and the geographical proximity of the two populations. The haplogroups P, BR(xB2b,DE,P) and E(xE3a), which are rare in sub-Saharan Africa but common in western Eurasia, were observed with frequencies ranging from 0.022 (haplogroup P) to 0.087 (haplogroup E(xE3a)). Thirty different microsatellite haplotypes were detected, with frequencies ranging from 0.022 to 0.152. The Mbenzele share the highest percent of microsatellite haplotypes with the Biaka Pygmies. Five out seven haplotypes which are shared by the Mbenzele and Biaka Pygmies belong to haplogroup E3a, which suggests that they are of Bantu origin. The plot based on F(st) genetic distances calculated using microsatellite data provides a picture of population relationships which is in part congruent and in part complementary to that obtained using haplogroup frequencies. Finally, the Mbenzele and Biaka Pygmies were found to be markedly more genetically similar using Y-chromosomal than autosomal microsatellites. We suggest that this could be due to the higher phylogenetic stability of Y-chromosome and to the effect of the male-biased gene flow during the Bantu expansion.

Sub-Saharan African coding sequence variation and haplotype diversity at theNAT2gene

“…demic diffusion and replacement, at least partially, of hunter-gatherers gene pools). Indeed, this observation is supported by mitochondrial DNA (Chen et al, 2000;Destro-Bisol et al, 2004) and Y-chromosome (Knight et al, 2003;Coia et al, 2004) analyses, which have reported a number of deep-rooting lineages shared by Pygmy (particularly Western Pygmies) and Khoisan populations. If natural selection has been the main force leading to the observed genetic affinities of both groups, one must invoke a selective advantage of the fast acetylator status (either by recent positive selection or by long-standing balancing selection) in populations with a hunter-gatherer lifestyle.…”

Multiple and differentiated contributions to the male gene pool of pastoral and farmer populations of the African Sahel

“…Various ethnic groups from Mozambique [49 E‐M2 chromosomes, 7 STR loci (Pereira et al, )]; 14. Mbenzele Pygmies [28 E‐M2 chromosomes, 6 STR loci (Coia et al, )]; 15. 11 ethnic groups from Tanzania [93 E‐M2 chromosomes, 8 STR loci (Tishkoff et al, )]; 16.…”

The Evolution of Human Genetic and Phenotypic Variation in Africa

“…Specifically, data have shown that the inferred ancestors of modern Pygmy hunter-gatherers and Bantu-speaking agriculturalists could have diverged as long as 70 kya [49], and that ancestral western and eastern Pygmy populations separated more than 18 kya [48] with subsequent genetic differentiation among the western Pygmies within the past 2,800 years [50]. The subtle structure among western Pygmies may be due to recent geographic isolation, genetic drift, and differential levels of admixture between Pygmies and neighboring Bantu-speaking populations [18, 49, 50, 52–54]. Overall, these patterns of genetic and phenotypic variation suggest that African populations have maintained a large and subdivided population structure throughout much of their evolutionary history.…”