Default parameter settings (Table 1). In each run, 441 variants were included: all combinations of and . Simulations were run for 1000 passaging episodes to reach evolutionary steady state, after which the phage variant distribution was plotted. For h phages with a fully lytic strategy () are selected. For h, phage variants with a sufficiently high response threshold () also occur. Under such short times between passages, the arbitrium concentration never reaches values during an epidemic, and phages with sufficiently high response threshold values hence display a lytic strategy only. For h phages are selected that switch from a fully lytic strategy at low arbitrium concentration to a fully lysogenic strategy () at high arbitrium concentration. For h, the selected response threshold value slowly decreases until it settles at approximately . This result is probably due to a residual presence of free phage particles that were produced during the early active epidemic phase. Since phage variants with a higher response threshold value switch to a lysogenic strategy later in the epidemic, they initially produce more free phage particles than phage variants that switch to a lysogenic strategy earlier. These additional phages disappear over time due to spontaneous degradation and adsorption to lysogens. If, however, some of these phages are still present when the population is passaged, this provides a small advantage to the phage variants that produced more of these early phages (i.e. the phages with a higher response threshold).