Figure 2.

Predicted fitness ± SEM of reconstruction mutants in the presence of or 0 (A), 117 (B), 233 (C), or 350 (D) µM ZnCl₂. Edge color reflects how the addition of each mutation (i.e., from bottom to top) affects fitness (green, increase; red decrease; significance was assessed using a linear model fitted to all Zn data). Solid lines represent significant changes, dotted lines nonsignificant ones. After sequential Bonferroni correction, only the comparisons at 117 μM remain significant. Bold, darker boxes correspond with (combinations of) mutations found in clones isolated from the long-term evolution experiment. Red fitness values represent global optima.