Biology and evolution of the Epichloë-associated Botanophila species found in Europe (Diptera: Anthomyiidae)

Abstract

The anthomyiid genus Botanophila consists of over 200, mostly phytophagous, species. One species group maintains a mutualistic relationship with Epichloë fungi, thereby acting as vector of fungal spermatia required for fertilization, similar to pollinating parasites. The phylogenetic relationship of these flies with other Botanophila and the related Chiastocheta species (obligatory associated with globeflowers) remains largely unresolved. In this study, we obtained new sequences of the mitochondrial genes COI and COII from a representative sample of 17 European Botanophila and Chiastocheta species including all six Epichloë-associated species, as well as from four outgroup taxa. Phylogenetic analyses indicated that Epichloë-associated Botanophila form a distinct clade suggesting that ancestral Botanophila may have expanded its niche to European fungal hosts once and then successfully radiated while exploiting fungal tissue as additional food source. Furthermore, the three included Chiastocheta species formed a distinct clade nested within Botanophila, leaving the genus paraphyletic as currently circumscribed.