title: Reevaluating a model of gender-biased gene flow among Sub-Saharan Hunter-gatherers and farmers.
abstract: In a previous study, we proposed a model for genetic admixture between African hunter-gatherers and food producers, in which we integrated demographic and genetic aspects together with ethnographic knowledge (Destro-Bisol et al. 2004b). In that study it was possible to test the model only using genetic information from widely dispersed and genetically heterogeneous populations. Here we reevaluate the congruence between the model and patterns of genetic variation using an anthropologically and geographically more homogeneous data set that includes Pygmies and farmers from Cameroon, Congo, and the Central African Republic. As implied by the model, the ratios of mtDNA to Y chromosome Nm estimates (effective population size, N, times the migration rate, m; 0.154 in Pygmies and 6.759 in farmers), support an asymmetric gene flow, with a higher Bantu-to-Pygmy gene flow for paternal than for maternal lineages, and vice versa for farmers. Analyses of intra- and interpopulation genetic variation further support the above observation, showing a prevailing effect of genetic drift on maternal lineages and gene flow on paternal lineages among Pygmies, and an opposite pattern among farmers. We also detected differences between patterns for classical and molecular measures of Y chromosome intrapopulation variation, which likely represent signatures of the introgression of Bantu lineages into the gene pool of Pygmy populations. On the whole, our results seem to reflect differences in the demographic history and the degree of patrilocality and polygyny between the two population groups, thus providing further support to our microevolutionary model in an anthropologically coherent framework.
authors.affiliation: Università di Roma "La Sapienza," Dipartimento di Biologia Ambientale, Rome, Italy and Istituto Italiano di Antropologia, Rome, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Anagnostou
authors.affiliation: Università di Roma "La Sapienza," Dipartimento di Biologia Ambientale, Rome, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Battaggia
authors.affiliation: Istituto Italiano di Antropologia, Rome, Italy and Università di Roma, "La Sapienza," Dipartimento Biologia e Biotecnologie "Charles Darwin," Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Capocasa
authors.affiliation: Istituto di Medicina Legale, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Boschi
authors.affiliation: Istituto di Medicina Legale, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Brisighelli
authors.affiliation: Department of Genetics, University of Leicester, Leicester, UK.
authors.forename: Chiara
authors.initials: C
authors.lastname: Batini
authors.affiliation: Università di Roma "La Sapienza," Dipartimento di Biologia Ambientale, Rome, Italy and Istituti Italiano di Antropologia, Rome, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Spedini
authors.affiliation: Università di Roma "La Sapienza," Dipartimento di Biologia Ambientale, Rome, Italy and Istituti Italiano di Antropologia, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Destro-Bisol
mesh_terms: D017954:Africa South of the Sahara; D000383:Agriculture; D044383:Black People / Q000235:genetics*; D041322:Chromosomes, Human, Y; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D051456:Gene Flow; D005828:Genetics, Population; D006801:Humans; D008297:Male; D008957:Models, Genetic
chemical_list: D004272:DNA, Mitochondrial