Figure 1.
Distribution of summary statistics from coalescent simulations of neutral and positively selected loci. Blue and light red bars represent summary statistics from neutral and selected simulations, respectively. Areas where the two distributions overlap are shaded purple. x-Axes indicate values for π (% per nucleotide) or Tajima's D, while y-axes are unit-less relative frequencies. (A,B) Recent (3500 generations) strong selection (sE = 2%) in Europe; (C,D) prolonged (17,000 generations) moderate selection (sE = 1%) in Africa. For ease of visualization, very rare values beyond the ranges of these graphs are not shown, and regions from simulations with selection (light red) are scaled as if their frequency were identical to that of regions from neutral simulations (blue). Relative to blue bars, light-red bars are skewed toward the left, indicating that regions linked to sites under selection tend to have lower values of π and Tajima's D; recombination diminishes this effect only slightly.