A very important finding of the paper is that the correlation between recombination rate and genetic differentiation (as measured by Fst) is stronger between Africans and non-Africans, and weaker between Europeans and Chinese. To simplify, we can say that Eurasians and Africans have diverged from each other to a great part because of selection (in either Eurasians, or Africans, or both) that took them away (genetically) from their common ancestor. On the other hand, differentiation between Europeans and Chinese is to a greater extent neutral, i.e., the result of demographic separation, rather than independent processes of selection.
PLoS Genetics doi:10.1371/journal.pgen.1000886
Human Population Differentiation Is Strongly Correlated with Local Recombination Rate
Alon Keinan et al.
Allele frequency differences across populations can provide valuable information both for studying population structure and for identifying loci that have been targets of natural selection. Here, we examine the relationship between recombination rate and population differentiation in humans by analyzing two uniformly-ascertained, whole-genome data sets. We find that population differentiation as assessed by inter-continental FSTshows negative correlation with recombination rate, with FST reduced by 10% in the tenth of the genome with the highest recombination rate compared with the tenth of the genome with the lowest recombination rate (P≪10−12). This pattern cannot be explained by the mutagenic properties of recombination and instead must reflect the impact of selection in the last 100,000 years since human continental populations split. The correlation between recombination rate andFST has a qualitatively different relationship for FST between African and non-African populations and for FST between European and East Asian populations, suggesting varying levels or types of selection in different epochs of human history.