Fig. 1: Schematic of the peripheral kill-the-winner hypothesis.

In the absence of phage, we expect that faster-growing antibiotic-sensitive (AS) cells (cyan) will displace slower-growing antibiotic-resistant (AR) cells (magenta) along the biomass periphery. In the presence of phage, however, we expect that the slower-growing AR cells will persist with the faster-growing AS cells. This is because the faster-growing AS cells will disproportionately occupy the biomass periphery, and they will therefore be more susceptible to phage lysis. This will increase the removal of AS cells from the biomass and counteract the benefits of their faster growth relative to the slower-growing AR cells, thus increasing the persistence of the slower-growing AR cells.