Food Plant Shifts Drive the Diversification of Sack-Bearer Moths

Abstract

Lepidoptera are a highly diverse group of herbivorous insects; however, some superfamilies have relatively few species. Two alternative hypotheses for drivers of Lepidoptera diversity are shifts in food plant use or shifts from concealed to external feeding as larvae. Many studies address the former hypothesis but with bias toward externally feeding taxa. One of the most striking examples of species disparity between sister lineages in Lepidoptera is between the concealed-feeding sack-bearer moths (Mimallonoidea), which contain about 300 species, and externally feeding Macroheterocera, which have over 74,000 species. We provide the first dated tree of Mimallonidae to understand the diversification dynamics of these moths in order to fill a knowledge gap pertaining to drivers of diversity within an important concealed-feeding clade. We find that Mimallonidae is an ancient Lepidoptera lineage that originated in the Cretaceous similar to 105 million years ago and has had a close association with the plant order Myrtales for the past 40 million years. Diversification dynamics are tightly linked with food plant usage in this group. Reliance on Myrtales may have influenced diversification of Mimallonidae because clades that shifted away from the ancestral condition of feeding on Myrtales have the highest speciation rates in the family.