Figure 2

Heat map showing changing gene expression patterns in ampicillin resistant E. coli. Each column represents one population grown in the absence of amp (C), or in the concentration of amp shown at the bottom. Each row shows the expression level across populations for one gene, with blue for low, red for high and yellow for intermediate expression. The endogenous β-lactamase gene, AmpC, shows elevated expression in most, but not all, ampicillin resistant populations.