Fig. 3.

Competitive efficiency of library competition winners relative to their precompetition ancestors. Winners and ancestors were individually competed against a single wild-type strain. After a 50:50 mixing, each culture was repeatedly passaged and the relative abundance of each strain determined at periodic time points by DNA sequencing and assessment of peak height ratios at sites differing between the mutant and wild-type strains. (A) Representative chromatograms at different time points in a pairwise competition demonstrating a temporal shift in culture composition. (B) Mutant:wild-type ratio as a function of generations of log-phase growth of winning mutators (green) and corresponding ancestors (blue) competed against wild type. Data points reflect triplicate cultures ± SE. (C) Mutant:wild-type ratio as a function of days of passage under library competition conditions. Data series within each panel represent individual cultures. Under both conditions, winners demonstrated a consistent growth advantage relative to wild type in contrast to the consistent disadvantage of their ancestors.