Abstract
There is a long-standing interest in understanding host-parasite coevolutionary dynamics and associated fitness effects. Increasing amounts of genomic data offer new ways to understand the past coevolutionary history. To extract such information, it is crucial to understand the link between allele frequency dynamics and polymorphism data. We couple coevolutionary models, which include costs of resistance, infectivity and infection, with coalescent simulations to generate polymorphism data at the involved loci. We show that under trench-warfare dynamics the allele frequencies at the internal equilibrium point determine the strength of the resulting balancing selection signatures.
As a proof-of-principle, we then apply an Approximate Bayesian Computation approach to infer the cost values using host and parasite polymorphism data from repeated experiments. First, we demonstrate that the cost of infection and host and parasite population sizes can be inferred knowing the costs of resistance and infectivity. Second, we can infer simultaneously all three costs when population sizes are known. Third, the polymorphism data in the host are informative about the cost of infectivity (parasite cost), while the signatures in the parasite inform about the cost of resistance and infection (host costs). We discuss the implications of our results for genomic based inference of host-parasite coevolution.
Footnotes
Email addresses: tellier{at}wzw.tum.de (Aurélien Tellier)