Figure 2 .

Distribution of fitness effects among pure vs. contaminated mutant genotypes. All distributions are based on the simulation of 100,000 independent mutant genotypes under the assumption of FGM parameterized as described in Materials and Methods. Note that for graphical convenience we do not display these empirical distributions as histograms but report here smoothed distributions. Orange: DFE of pure single-step mutant genotypes (ideal conditions) Gray: DFE of mutant genotypes carrying one mutation affecting fitness plus a Poisson-distributed number of extra mutations (rate of contamination, λ = 0.5). This generates a mixture of pure single-step mutants contaminated with genotypes carrying extra mutations affecting fitness. (A) m = 5; E(s) = 0.01; s_o = 0.05. (B) m = 5; E(s) = 0.01; s_o = 0.01. (C) m = 2; E(s) = 0.01; s_o = 0.05; Poisson rate of contamination, λ = 0.5. (D) m = 2; E(s) = 0.01; s_o = 0.01; Poisson rate of contamination, λ = 0.5.