Recent Selective Sweeps in North American Drosophila melanogaster Show Signatures of Soft Sweeps
Fig 10
H2/H1 values measured in sweeps of varying softness.
Similar to Fig. 5, H2/H1 values were measured in simulated sweeps arising from (A) de novo mutations with θA values ranging from 10–2 to 102 and (B) SGV with starting frequencies ranging from 10–6 to 10–1. Sweeps were simulated under a constant Ne = 106 demographic model with a recombination rate of 5×10-7 cM/bp, selection strength of s = 0.01, ending partial frequencies of the adaptive allele after selection ceased, PF = 1 and 0.5, and in samples of 145 individuals. Each data point was averaged over 1000 simulations. H2/H1 values rapidly increase with increasing softness of a sweep, but do not depend strongly on PF. In (C) and (D), s was varied while keeping PF constant at 0.5 for sweeps from de novo mutations and SGV, respectively. In the case of sweeps from SGV, H2/H1 values increase as s increases, reflecting a hardening of sweeps with smaller s. In (E) and (F), the time since selection ended (TE) was varied for incomplete (PF = 0.5) and complete (PF = 1) sweeps respectively while keeping s constant at 0.01. As the age of a sweep increases, the sweep signature decays and H2/H1 approaches one.