Figure 2. .

Fraction of de novo missense mutations represented at different levels of allele frequency. The normalized fraction of de novo amino acid substitutions detected in a given data set was calculated from the difference of observed N_a/N_s ratio and theoretical N⁰_a/N⁰_s ratio expected under neutrality. Data for rare polymorphisms are shown in orange, data for common polymorphisms are in yellow, and data for substitutions (subst.) fixed in the human lineage after divergence from chimpanzee are in green. SEs are shown by gray error bars.