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Fig. 1 | BMC Biology

Fig. 1

From: Sexual conflict maintains variation at an insecticide resistance locus

Fig. 1

The theoretical allele frequencies with and without DDT imposed selection. (a) The model parameter space showing three different equilibrium regions. If the upper surface is exceeded DDT-R goes to fixation. Below the lower surface DDT-R cannot invade. A stable internal equilibrium, where both resistant and susceptible genotypes co-occur, exists in the envelope between the two surfaces. (b) Model DDT-R genotype and allele trajectories approach a stable internal equilibrium. Model run over 50 generations with fitness parameters at default Canton-S values (Table 1). (a) and (b): initial genotype frequencies x RR = 0, x RS = 0.1, x SS = 0.9; (c) and (d) initial genotype frequencies x RR = 0.9, x RS = 0.1, x SS = 0. In plots (a) and (c) the red line represents the frequency of x RR , the blue line x RS , the green lines x SS , and the black line is DDT-R. Ternary plots (b) and (d) show genotype trajectory (red dots connected by black lines), equilibria (open circles are unstable equilibria, black circle is stable equilibrium) and genotype vector field (blue arrows). (c) The effect of added DDT viability selection on model DDT-R genotype and allele trajectories. Fitness parameters set to default Canton-S values (Table 1) starting from initial genotype frequencies x RR = 0, x RS = 0.001, x SS = 0.999. The red line is the frequency of x RR , the blue line is x RS , the green line is x SS , and the black line is DDT-R. The internal equilibrium of 34 % in the absence of DDT selection is achieved within the first 20 generations (in the ‘pre-DDT’ period). DDT selection (shaded area) starts at generation 201 and ends at generation 500, by which time DDT-R has acquired a frequency greater than 99 %. More than 300 subsequent generations are required ‘post- DDT’ for the stable internal equilibrium to be regained

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