FIG. 4.

Population genetics model of resistance selection in mixed culture. Deterministic two-locus two-allele models fit by ordinary least-squares estimation calculated using the Davidson-Fletcher-Powell optimization function in the R package Bhat are shown for group C. The allele frequencies predicted by the model are shown by lines, while the actual measured frequencies are shown as points. The wild type is shown in black, mutation 370A is shown in red, mutation 362I is shown in blue, and the 362I/370A double mutant is shown in green. Fitness estimates with 95% confidence intervals are shown in the table in the lower right panel. In some instances, the predicted trajectory of allele frequencies overshot the boundary (at 0 and 1) due to the discrete-time approximation used in the population genetic model.