Mean nonsynonymous substitution rate (K_A) in mutually exclusive groupings of genes with RNAi phenotypes of sterility (Ste), embryonic lethality (Emb), sterility and embryonic lethality, some other observed phenotype (other RNAi⁺), and no observed phenotype (RNAi^-). Ste and Emb loci include loci with both partial and complete sterility or lethality, respectively. Error bars, ±1 SE.