Figure 5.

Strain frequencies (colours) and overall resistance frequency (grey) as a function of the population antibiotic consumption rate (τ) for different costs of the producer and immune strains. $c_{\beta }$ indicates cost in transmission and $c_{\mu }$ indicates cost in clearance, with P and M indicating the cost to the producer and immune strain, respectively: in the top row, bacteriocin-associated costs affect transmission, in the bottom row these affect clearance. The cost of antibiotic resistance (c_R = 0.025) is modelled as affecting transmission (see electronic supplementary material, section 2.6 for antibiotic resistance costs modelled as affecting clearance). Other parameters are β = 3, μ = 1, k_PN = 1, k_MP = k_NM = 0.5. The model is parameterized such that the values of the rate parameters in units of month⁻¹ are plausible for S. pneumoniae [28]. Due to the difficulty of computing equilibrium solutions and eigenvalues for this model, these results are derived through simulating rather than stability analysis (simulation until $t={10}^5\hspace{0.17em}\mathrm{months}$).