Modeling spatial evolution of multi-drug resistance under drug environmental gradients
Fig 8
Fitness ranking among 3 mutants for periodic drug regimes, as a function of spatial period of drug 2.
A. Synergistic drug interaction. B. Independent drug action C. Antagonistic drug interaction. The strength of interaction when assumed, was q = 0.5 and G(x, y) were specified as in Eq 16. The periodic variation of drug 1 x(z) was held fixed, while drug 2 concentration y(z) over space was varied by varying the period T2. These parameters were fixed: k1 = A1 = 0.5, T1 = 0.8 and k2 = A2 = 0.5 before normalization, which then leads to total conservation of drug 1 and drug 2, fixed amount = 1 for each spatial period of drug 2 T2. Final fitnesses of the 3 mutants over space, computed on the basis of the principal eigenvalue. Assumed diffusion coefficient is D = 0.01. In blue: single-resistance to drug 1, in red: single-resistance to drug 2, in purple: double resistant mutant with intermediate resistance to each drug.