Data from: Phoretic Poecilochirus mites specialise on their burying beetle hosts

Recurring species interactions can cause species to adapt to each other.
Specialization will increase the fitness of symbionts in the coevolved
association but may reduce the flexibility of symbiont choice as it will
often decrease fitness in interactions with other than the main symbiont
species. We analyzed the fitness interactions between a complex of two
cryptic mite species and their sympatric burying beetle hosts in a
European population. Poecilochirus mites (Mesostigmata, Parasitidae) are
phoretic on burying beetles and reproduce alongside beetles, while these
care for their offspring at vertebrate carcasses. While Poecilochirus
carabi is typically found on Nicrophorus vespilloides beetles, P.
necrophori is associated with N. vespillo. It has long been known that the
mites discriminate between the two beetle species, but the fitness
consequences of this choice remained unknown. We experimentally associated
both mite species with both beetle species and found that mite fitness
suffered when mites reproduced alongside a nonpreferred host. In turn,
there is evidence that one of the beetle species is better able to cope
with the mite species they are typically associated with. The overall
fitness effect of mites on beetles was negative in our laboratory
experiments. The Poecilochirus mites studied here are thus specialized
competitors or parasites of burying beetles.