FIG 2.

Virulence phenotypes and growth rates of evolved S. aureus isolates. (A) Average invasiveness of isolates selected for enhanced-virulence phenotypes. (B) Average cytotoxicities of isolates selected for enhanced-virulence phenotypes. (C) Average doubling times of isolates selected for enhanced-virulence phenotypes. (A to C) Measurements were normalized to the parental strain, and isolates were aggregated by selection type and time of passaging. The reference activity of the wild-type strain (set to 1) is highlighted on each y axis. The data points correspond to individual strains, the horizontal lines indicate medians for aggregated groups of strains, and the error bars indicate the SEM for the groups. Note the log₂ scale in panel A. Populations that are significantly different (Z test) from the parental strain are indicated by asterisks: *, P < 0.05; **, P < 0.001.