Figure 3.

Competitive fitness of new WT‐lysogens relative to each of three competing ancestral strains (left: in competition with the phage‐free, ARG‐free Wild Type; middle: in competition with an ARG‐free lysogen with the same prophage type; right: in competition with an ARG‐carrying lysogen with the same prophage type). Fitness was measured in the absence and presence of antibiotics (x‐axis). Different colors correspond to different ARGs (see legend). Each line gives the mean ± s.e. across all of the new‐WT lysogens we isolated for each ARG; individual reaction norms for every new WT‐lysogen (each isolated from one of the 16 populations where we detected new lysogens, Table 2) are given in Figure S8. New WT‐lysogens have a higher fitness than the competing strain when r > 0.