Figure 2.

Positive niche construction, independent renewal, and heterozygote advantage (R_t = λ₁R_t−1 + λ₂p_t + λ₃, γ = 0, α₁ = α₂ = 0.99, β₁ = β₂ = 0.9, r = 1/2, n = 1). Provided r is not very small, populations converge to a single equilibrium in linkage equilibrium, the position of which may be strongly affected by niche construction. The + represents the equilibrium in the absence of niche construction. By increasing R, niche construction changes the frequency-dependent component of genotype fitnesses, affecting the equilibrium frequency of allele A. In both a and b, without niche construction, allele a would be fixed, whereas in a, niche construction allows A and a to coexist, and in b, niche construction drives A to fixation.