Fig. 1

Dynamics of β^C and β^S frequencies under different malaria mortality functions. In each simulation shown, β^C starts at a frequency of 5.6 % and β^S starts at a frequency of 0.3 %, equivalent to a single β^S heterozygote in a population of 150 individuals (e.g., after a mutation arises de novo or is imported into a small population). The malaria mortality function applied in all panels is f ₁ , where x = 0.01 and z = 0.015. In a, γ = 0, thus malaria mortality is independent of allele frequency. In b, γ = 10 and malaria mortality increases with β^C frequency (u = p); in c, γ = 10 and malaria mortality increases with β^S frequency (u = q). Baseline mortality rates and malaria susceptibilities of each genotype are given in tables S1 and S2