A link between heritable parasite resistance and mate choice in dung beetles

Parasites play a central role in the adaptiveness of sexual reproduction. Sexual selection theory suggests a role for parasite resistance in the context of mate choice, but the evidence is mixed. The parasite-mediated sexual selection (PMSS) hypothesis derives a number of predictions, among which that resistance to parasites is heritable, and that female choice favours parasite resistance genes in males. Here we tested the PMSS hypothesis using the dung beetle Onthophagus taurus, a species that can be heavily parasitised by Macrocheles merdarius mites, which are known to affect adult survival. We investigated the heritability of resistance to M. merdarius, as well as whether female O. taurus impose a mating bias against males susceptible to mite infestation. Female choice for parasite resistance is difficult to disentangle from the possibility that females are simply choosing less parasitised males due to naturally selected benefits of avoiding contracting those parasites. This is espec...