Figure 3
Adaptive nature of the expansion. Cultures of TP1004, an MG1655 derivative bearing the (lacIZ33Y)2-cat duplication, were plated on minimal agar in which lactose was made available as the only available carbon source, either at the time of plating (circles), or after two (triangles) or four (squares) days of incubation. Data points represent mean daily colony counts from 12 independent cultures. Error bars are omitted for clarity; as in Fig. 2, the standard deviations are comparable in magnitude to the means.