Fig. 2.

Fitness of serially passaged lineages. (A) Relative growth rate of WT (•) and mutS (○) lineages of S. typhimurium LT2 after 30, 90, and 270 cycles of serial passage on hematin agar plates. The 270 cycles represent ≈6,750 generations of bacterial growth. (B) Relative growth rate of three mutS lineages that were first given 90 cycles of serial passage followed by evolution for 100 generations in large populations to allow selection for faster growth. Slow-growing parental mutS strain (•) and growth-compensated mutants (○) are indicated.