Fig. 5.

Long-lived coexistence for a broad range of and . Shown is duration of coexistence as a function of and (). Red lines mark and for in the basic model. If time reached 1,000 bacterial generations while there was still coexistence (i.e., both phage and bacteria were present), then the simulation was stopped. Only parameter sets where were considered. Within the region where and the phage and bacteria coexisted for durations much longer than the bacterial generation time. In this region, the average infection front speeds were also relatively low (SI Appendix). When and , the phage live for a short time on the edge of the expanding bacterial colony before dying out. When and , the phage infection fronts rapidly eat into the colonies and eventually wipe out the bacteria. In the small region where both and are within the narrow range of , there is stable coexistence. Grid size: 100 × 100. Initial conditions: upper half-plane filled by uninfected bacteria and a single line of infected bacteria on the boundary between the upper part and the empty lower half-plane.