Fixed Deleterious Mutations Are Found in Genotypes That Are More Fit Than the Ancestral Genotype in Which the Deleterious Mutation Arose

<p>In each graph, the gray lines correspond to <i>g_i</i> and the black lines to . We define the fitness of descendent genotypes relative to the ancestor as ((<i>W_desc − W_anc)/W_anc</i>), where <i>W_anc</i> is the fitness of the parent genotype that gave rise to the deleterious mutation and <i>W_desc</i> may mean the fitness of <i>g_i</i> or . The error bars depict one standard error of the mean. (A) and (B) show the change in fitness of the genetic backgrounds harboring the fixed deleterious mutations in the <i>U</i> = 0.08 and <i>U</i> = 0.32 runs, respectively. (C) and (D) show the change in fitness of the genetic backgrounds of random deleterious mutations that did not fix in the <i>U</i> = 0.08 and <i>U</i> = 0.32 runs, respectively.