title: The role of geography in human adaptation.
abstract: Various observations argue for a role of adaptation in recent human evolution, including results from genome-wide studies and analyses of selection signals at candidate genes. Here, we use genome-wide SNP data from the HapMap and CEPH-Human Genome Diversity Panel samples to study the geographic distributions of putatively selected alleles at a range of geographic scales. We find that the average allele frequency divergence is highly predictive of the most extreme F(ST) values across the whole genome. On a broad scale, the geographic distribution of putatively selected alleles almost invariably conforms to population clusters identified using randomly chosen genetic markers. Given this structure, there are surprisingly few fixed or nearly fixed differences between human populations. Among the nearly fixed differences that do exist, nearly all are due to fixation events that occurred outside of Africa, and most appear in East Asia. These patterns suggest that selection is often weak enough that neutral processes -- especially population history, migration, and drift -- exert powerful influences over the fate and geographic distribution of selected alleles.
authors.affiliation: Department of Human Genetics, University of Chicago, Chicago, IL, USA. gmcoop@ucdavis.edu
authors.forename: Graham
authors.initials: G
authors.lastname: Coop
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Pickrell
authors.forename: John
authors.initials: J
authors.lastname: Novembre
authors.forename: Sridhar
authors.initials: S
authors.lastname: Kudaravalli
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Devin
authors.initials: D
authors.lastname: Absher
authors.forename: Richard M
authors.initials: RM
authors.lastname: Myers
authors.forename: Luigi Luca
authors.initials: LL
authors.lastname: Cavalli-Sforza
authors.forename: Marcus W
authors.initials: MW
authors.lastname: Feldman
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Pritchard
mesh_terms: D000349:Africa; D005202:Asia, Eastern; D005787:Gene Frequency; D014644:Genetic Variation; D005828:Genetics, Population; D015894:Genome, Human; D055106:Genome-Wide Association Study; D005843:Geography; D006239:Haplotypes; D006801:Humans; D020641:Polymorphism, Single Nucleotide