Figure 1

Transient crash in final cell densities over the course of adaptation. Colony counts from dilutions of the final population sizes at various transfers indicated that six of eight E populations (shown in black) crashed before recovering. The E2 population (indicated with large circular symbols and a dotted line) stayed at moderately low densities until after 120 generations. In contrast, the F populations (grey, first 48 generations displayed), whose medium was supplemented with the rapidly-consumed substrate succinate for the first growth cycle to assure full density was reached from single colonies, did not exhibit this pattern.