Fig. 3.

A single mutation potentiator of G × E effects, S117N, has uncommonly high fitness effects across a range of drug concentrations, and creates alleles that are of higher fitness. a Each colour represents the Δ fitness effect of a one of the four mutations, the difference between a genotype with and without a mutation. Each mutation has 8 possible genetic backgrounds. Small (unconnected) symbols are representative of Δ fitness effect measures for individual mutation effects in a particular genetic background. Large symbols, connected by lines, represent the average Δ fitness effect of a mutation over all 8 genetic backgrounds. The third site (S117N) mutation has a strong effect, creating high fitness alleles that foster forward evolution and inhibit reverse evolution. The x-axis is in units ln(concentration of PYR + 1) μM. b Whole alleles carrying the G × E pivot mutation (**1*) have significantly higher growth rates than the other alleles (averaged across drug concentrations). This graph differs from a because this does not depict fitness effects of single mutations, but rather, the total average fitness of whole alleles carrying the specified mutation