Fig. 4

Negative frequency-dependent selection and arms race dynamics. Revival of genotypes and evolution of host (top) and parasite (middle) populations with five possible genotypes each. With the rate μ_H=0.005 and μ_P=0.01 genotypes convert to neighbouring genotypes through mutation or recombination. Stacked plots – evolutionary dynamics: the area covered by one colour is proportional to the relative abundance of that genotype of host or parasite at that time. Lower panel – ecological dynamics: total abundance of hosts and parasites. Method: the example is a stochastic simulation (Gillespie algorithm) of an EcoEvo ⁺ process. The simulations start with equal abundance of all five genotypes H_i(0)=N_H/5 and P_i(0)=N_P/5 for i=1,2,3,4,5. Parameters: N_H=300,N_P=900 (both initially), b_H=6,d_P=1,K=600,λ₀=10