Fig. 5.

The effect of ψ_SR and ψ_RR on $p^{*}$ (the equilibrium R allele frequency) in the non-target deme. The model is spatial, with release ratio d=20, and a strong partially dominant incomplete resistance (${\gamma }_{\mathit{SR}}=0.2$, ${\gamma }_{\mathit{RR}}=0.1$). Dispersal rates m=0.01 (a), m=0.05 (b) and m=0.1 (c) are used. Only points where ${\psi }_{\mathit{SR}}\ge {\psi }_{\mathit{RR}}$ (so that heterozygote resistance is always less costly than homozygote resistance) are shown. The threshold increase in $p^{*}$ can clearly be seen at high ψ_SR and ψ_RR values (low costs of resistance).