title: Contrasting signatures of population growth for mitochondrial DNA and Y chromosomes among human populations in Africa.
abstract: A history of Pleistocene population expansion has been inferred from the frequency spectrum of polymorphism in the mitochondrial DNA (mtDNA) of many human populations. Similar patterns are not typically observed for autosomal and X-linked loci. One explanation for this discrepancy is a recent population bottleneck, with different rates of recovery for haploid and autosomal loci as a result of their different effective population sizes. This hypothesis predicts that mitochondrial and Y chromosomal DNA will show a similar skew in the frequency spectrum in populations that have experienced a recent increase in effective population size. We test this hypothesis by resequencing 6.6 kb of noncoding Y chromosomal DNA and 780 basepairs of the mtDNA cytochrome c oxidase subunit III (COIII) gene in 172 males from 5 African populations. Four tests of population expansion are employed for each locus in each population: Fu's Fs statistic, the R(2) statistic, coalescent simulations, and the mismatch distribution. Consistent with previous results, patterns of mtDNA polymorphism better fit a model of constant population size for food-gathering populations and a model of population expansion for food-producing populations. In contrast, none of the tests reveal evidence of Y chromosome growth for either food-gatherers or food-producers. The distinct mtDNA and Y chromosome polymorphism patterns most likely reflect sex-biased demographic processes in the recent history of African populations. We hypothesize that males experienced smaller effective population sizes and/or lower rates of migration during the Bantu expansion, which occurred over the last 5,000 years.
authors: Department of Anthropology, University of Arizona, USA.
authors: Maya Metni
authors: MM
authors: Pilkington
authors: Jason A
authors: JA
authors: Wilder
authors: Fernando L
authors: FL
authors: Mendez
authors: Murray P
authors: MP
authors: Cox
authors: August
authors: A
authors: Woerner
authors: Thiep
authors: T
authors: Angui
authors: Sarah
authors: S
authors: Kingan
authors: Zahra
authors: Z
authors: Mobasher
authors: Chiara
authors: C
authors: Batini
authors: Giovanni
authors: G
authors: Destro-Bisol
authors: Himla
authors: H
authors: Soodyall
authors: Beverly I
authors: BI
authors: Strassmann
authors: Michael F
authors: MF
authors: Hammer
mesh_terms: D000349:Africa; D041322:Chromosomes, Human, Y / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics*; D005828:Genetics, Population; D006801:Humans; D008297:Male; D011110:Polymorphism, Genetic; D011156:Population Density
chemical_list: D004272:DNA, Mitochondrial; D003576:Electron Transport Complex IV