FIG. 1.—

The trajectories of fitness recovery. The error bars indicate standard errors. The gray bars below the fitness trajectories indicate the presence of the mutations labeled at the right, on the basis of sequencing the populations for which fitness was measured. Mutations are labeled with the gene name and position of the affected amino acid residue. More information on these mutations is provided in table 3, and the raw fitness data from the populations are provided in table 2.