Figure 2.

Evolutionary stability of plasmid‐borne and chromosomal resistance. The colors indicate which form of resistance is evolutionarily stable: only chromosomal resistance (orange); only plasmid‐borne resistance (blue); or either (purple). When resistance is chromosomal, the sensitive plasmid can either be present or absent from the population (dark vs light orange). In the white space in the left‐hand panel, neither form of resistance is stable (the population is antibiotic‐sensitive). Parameter values are: $\lambda =1$, $\gamma =1$, $s=0.005$. For left‐hand panel $c_P$ = 0.075 and $\beta =0.2$. For right‐hand panel $A=1$ and $c_R=0.05$. Figures S1 and S2 show results for more parametrizations. Note that in the parameter space where resistance is beneficial, it can either be essential ($A\ge \lambda$: antibiotic susceptible cells are not viable, even in the absence of competition from resistant cells) or non‐essential. This distinction does not impact our results (Figs. S1 and S2).