Data from: Host-parasitoid evolution in a metacommunity

Patch size and isolation are predicted to alter both species diversity and
evolution; yet, there are few empirical examples of eco-evolutionary
feedback in metacommunities. We tested three hypotheses about
eco-evolutionary feedback in a gall-forming fly, Eurosta solidaginis and
two of its natural enemies that select for opposite traits: (i)
specialization and poor dispersal ability constrain a subset of natural
enemies from occupying small and isolated patches, (ii) this constraint
alters selection on the gall fly, causing phenotypic shifts towards traits
resistant to generalist and dispersive enemies in small and isolated
patches, and (iii) reduced dispersal evolves in small, isolated
populations. We sampled patches in a natural metacommunity and found
support for all hypotheses; Eurosta's specialist wasp parasitoid
attacked fewer galls in small and isolated patches, generating a selection
gradient that favoured small galls resistant to predation by a dispersive
and generalist bird predator. Phenotype distributions matched this
selection gradient, and these phenotypic differences were maintained in a
common garden experiment. Finally, we found lower dispersal abilities in
small and isolated patches, a phenotypic shift that aids in the
maintenance of local adaptation. We suggest that the trophic rank and the
species traits of consumers are central to evolution in metacommunities.