Fig 2.

Polygenic signals of sex-differential selection: Inflation in ${\widehat{F}}_{ST}$ metrics relative to their nulls. (A–C) Percentage of sites (coloured, observed; grey, permuted) falling into each of 100 quantiles of the theoretical null distributions of adult ${\widehat{F}}_{ST}$ (A), reproductive ${\widehat{F}}_{ST}$ (B), and gametic ${\widehat{F}}_{ST}$ (C). Theoretical null data (x-axes) were generated by simulating values (nSNPs = 1,051,949) from a chi-square distribution with 1 degree of freedom. For each locus, observed and permuted ${\widehat{F}}_{ST}$ values were scaled by the multiplier of the relevant theoretical null distributions (i.e., the multiplier in Eqs [3A–3C] for adult, reproductive, and gametic ${\widehat{F}}_{ST}$, respectively; see Materials and methods). In the absence of sex differences in selection, approximately 1% of observed SNPs should fall into each quantile of the null (dashed line). LOESS curves (±SE) are presented for visual emphasis. (D–F) Difference between the mean of observed and empirical null data for each metric (i.e., adult, reproductive, and gametic ${\widehat{F}}_{ST}$, respectively) (top), and the difference between observed and theoretical null data (bottom), across 1,000 bootstrap replicates. Vertical line intersects zero (no difference between observed and null data). As in panels (A–C), ${\widehat{F}}_{ST}$ values were scaled by the relevant theoretical null distributions. The code and data needed to generate this figure can be found at https://github.com/filipluca/polygenic_SA_selection_in_the_UK_biobank and https://zenodo.org/record/6824671. SNP, single-nucleotide polymorphism.