Higher-fitness yeast genotypes are less robust to deleterious mutations

Abstract

Genetic background affects variation Robustness, or the effect of mutations on fitness, can affect the evolutionary trajectory of a species. By introducing a large number of deleterious mutations into many different genetic backgrounds of yeast, Johnson et al. found that, for many mutations, the more fit the background, the larger the deleterious effect of the mutation (see the Perspective by Miller). A more-fit lineage is thus less tolerant to deleterious mutations, whereas less-fit lineages can tolerate more mutations. This observation supports a tendency toward diminishing returns for beneficial mutations, which has been shown to influence patterns of adaptation. Science , this issue p. 490 ; see also p. 418