Figure 3 .

Example evolutionary patterns for slightly deleterious and advantageous mutations. (A) Probability density function for positive selection coefficients (gamma distribution with shape parameter 1 and scale parameter 5 × 10⁻⁷). (B) Cumulative distribution function for selective effects of new mutations. y-Axis values are the total areas under the curve for 0 < s < x in A. f′_n for a given population size is the y-axis value at x = 1/N_e (values are marked for N_e of 10⁴, 10⁶, 10⁸). Almost all beneficial mutations are effectively neutral in N_e of 10² and 10⁴, and almost none are effectively neutral in N_e of 10⁸. (C) Cumulative distribution function for N_es or scaled selective effects. y-Axis values are the areas under the DSE curve for 0 < N_es < x in A. Curves are shown for N_e values of 10², 10⁴, 10⁶, and 10⁸ (thicker lines represent larger population sizes). f′_n values are shown as solid circles for each population size. (D) Polymorphism and divergence as a function of N_e for a distribution of fitness effects that combines the density functions in Figure 2A (99% of new mutations) and Figure 3A (1% of new mutations). The dashed line shows the proportion of advantageous fixations. Expected DNA diversity (π_N/π_S, dotted line) and divergence (d_N/d_S, solid line) are shown. These predictions assume independent evolution among sites.