A Genomic map of positive selection in Sardinia

The recent production of population-scale genomic data offers an unprecedented opportunity to understand how natural selection has shaped human phenotypic variation within populations. To identify signatures of recent positive selection in Sardinia, we used 23 million single nucleotide polymorphisms from low-coverage whole genomes of 3,514 Sardinians along with data from the 1000 Genomes project. Using single-population (iHS, nSL) and cross-population (Fst, PBS, XP-EHH) based statistics, we found many genetic regions showing evidence of positive selection. We found that selection statistics computed for outlier variants cannot be explained by neutral forces alone. By intersecting genome-wide association study data for hundreds of traits measured in Sardinians with publicy available functional genomic databases, we found that autoimmunity-related genes are enriched for these putatively adaptive variants.Taken together, these results illustrate the importance of characterizing the phenotypic variation within a population, and especially the utility of whole-genome-sequence data, when proposing and interpreting genetic signatures of positive selection.