title: Highly punctuated patterns of population structure on the X chromosome and implications for African evolutionary history.
abstract: It is well known that average levels of population structure are higher on the X chromosome compared to autosomes in humans. However, there have been surprisingly few analyses on the spatial distribution of population structure along the X chromosome. With publicly available data from the HapMap Project and Perlegen Sciences, we show a strikingly punctuated pattern of X chromosome population structure. Specifically, 87% of X-linked HapMap SNPs within the top 1% of F(ST) values cluster into five distinct loci. The largest of these regions spans 5.4 Mb and contains 66% of the most highly differentiated HapMap SNPs on the X chromosome. We demonstrate that the extreme clustering of highly differentiated SNPs on the X chromosome is not an artifact of ascertainment bias, nor is it specific to the populations genotyped in the HapMap Project. Rather, additional analyses and resequencing data suggest that these five regions have been substrates of recent and strong adaptive evolution. Finally, we discuss the implications that patterns of X-linked population structure have on the evolutionary history of African populations.
authors.affiliation: Department of Genetics, University of Pennsylvania, Philadelphia, 19104, USA.
authors.forename: Charla A
authors.initials: CA
authors.lastname: Lambert
authors.forename: Caitlin F
authors.initials: CF
authors.lastname: Connelly
authors.forename: Jennifer
authors.initials: J
authors.lastname: Madeoy
authors.forename: Ruolan
authors.initials: R
authors.lastname: Qiu
authors.forename: Maynard V
authors.initials: MV
authors.lastname: Olson
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Akey
mesh_terms: D000483:Alleles; D044383:Black People / Q000235:genetics*; D041321:Chromosomes, Human, X; D030541:Databases, Genetic; D019143:Evolution, Molecular; D005787:Gene Frequency; D005828:Genetics, Population; D015894:Genome, Human; D005838:Genotype; D006801:Humans; D008957:Models, Genetic; D020641:Polymorphism, Single Nucleotide; D044382:Population Groups / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014481:United States; D001741:Black or African American