Multiple and Differentiated Contributions to the Male Gene Pool of Pastoral and Farmer Populations of the African Sahel

Jana Bučková, Viktor Černý et Andrea Novelletto, "Multiple and Differentiated Contributions to the Male Gene Pool of Pastoral and Farmer Populations of the African Sahel", dans American Journal of Physical Anthropology, vol. 151, issue 1, mars 2013, p. 10-21.

Résumé

The African Sahel is conducive to studies of divergence/admixture genetic events as a result of its population history being so closely related with past cli- matic changes. Today, it is a place of the co-existence of two differing food-producing subsistence systems, i.e., that of sedentary farmers and nomadic pastoralists, whose pop- ulations have likely been formed from several dispersed indigenous hunter-gatherer groups. Using new methodol- ogy, we show here that the male gene pool of the extant populations of the African Sahel harbors signatures of multiple and differentiated contributions from different genetic sources. We also show that even if the Fulani pas- toralists and their neighboring farmers share high fre- quencies of four Y chromosome subhaplogroups of E, they have drawn on molecularly differentiated subgroups at different times. These findings, based on combinations of SNP and STR polymorphisms, add to our previous knowl- edge and highlight the role of differences in the demo- graphic history and displacements of the Sahelian populations as a major factor in the segregation of the Y chromosome lineages in Africa. Interestingly, within the Fulani pastoralist population as a whole, a differentiation of the groups from Niger is characterized by their high presence of R1b-M343 and E1b1b1-M35. Moreover, the R1b-M343 is represented in our dataset exclusively in the Fulani group and our analyses infer a north-to-south Afri- can migration route during a recent past.

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