Fig. 3.

Mutant alleles with more severe defects tend to have a higher percentage of negative epistasis in eukaryotes than bacteria and archaea. The y axis shows the percentage of mutant pairs in which mutant alleles with more severe defects in the same gene have a higher percentage of negative epistasis than the other allele. FBA simulations were conducted for three bacterial species (E. coli, S. typhimurium, and H. pylori), one archaea species (M. barkeri), and two single-cell eukaryote species (P. falciparum and S. cerevisiae). The mean and SEs were based on results from 40 epistasis threshold values ranging from 0.01 to 0.05.