Botanophilia flies associated with Epichloe host species: no evidence for coevolution

Abstract

Epichloë species usually depend on flies of genus Botanophila which transfer gametes for sexual reproduction. Sequence analysis of COII detected six distinct Botanophila taxa that were associated with Epichloë in Europe and North America. Three were restricted to samples from Europe, two to samples from North America, and one was present on both continents. In North America the common taxon (identified as B. lobata) was found on Epichloë hosts of native grasses as well as on E. typhina and E. festucae of introduced grasses. In Switzerland, up to four different Botanophila taxa occurred at a single location. There was no strict specificity of flies for Epichloë host species, although several taxa appeared to prefer some hosts over others. Comparison of the Botanophila phylogeny with that of the associated Epichloë hosts did not suggest co-evolution of fungus and fly. Thus, associations between Botanophila flies and Epichloë hosts may have arisen independently more than once. Keywords: Anthomyiidae, Diptera, Clavicipitaceae, choke disease, cytochrome oxydase, grass endophytes, molecular phylogeny, mutualism