Epistatic Interactions Alter Dynamics of Multilocus Gene-for-Gene Coevolution
Figure 2
Phase diagram of coevolutionary dynamics, showing coevolutionary outcomes of different combinations of cH–cP.
Here we follow the terminology of Sasaki (2000) and define regions to be of either coevolutionary cycles (“cycles”; no shading), double-resistance-no-virulence (“DR/NV”, where all hosts in the population have two resistance genes and no parasites have virulence genes; light shading), single-resistance-no-virulence (“SR/NV”, where all hosts have a single resistance gene and no parasites have virulence genes; intermediate shading) or no-resistance-no-virulence (“NR/NV”, where no hosts have resistance genes and no parasites have virulence genes; dark shading) occur. (A) the parasite has deceleratingly costly epistasis, (B) the parasite has linear epistasis and (C) the parasite has acceleratingly costly epistasis. In all cases the host has deceleratingly costly epistasis. The dashed lines show the boundary separating the regions where every simulation out of 20 replicates resulted in coevolutionary cycles (below the line) and where at least one of the replicate simulations resulted in a static single-resistance-no-virulence equilibrium (above the line).