Evolution of Manduca sexta hornworms and relatives: Biogeographical analysis reveals an ancestral diversification in Central America

Abstract

The hawkmoth genus Manduca is a diverse group of very large, conspicuous moths that has served as an important model across many biological disciplines. Two species in particular, the tobacco hornworm (Manduca sexta) and the tomato hornworm (Manduca quinquemaculatus) have been researched extensively. Studies across biological fields have referred to these two species as being closely related or even sister species, but the extent to which these two model organisms are related remains largely unknown. We conducted a comprehensive multi-gene phylogenetic analysis of Manduca, based on both an ML and Bayesian framework, which resulted in a monophyletic Manduca but only when two other genera, Dolba and Euryglottis are included. We tentatively conclude that the sister group to Manduca sexta comprises the Caribbean M. afflicta and M. johanni, and the sister lineage to this clade includes M. quinquemaculatus and the Hawaiian M. blackburni. Thus, M. sexta and M. quinquemaculatus are closely related, but are not sister species. Biogeographical analyses reveal an ancestral center of diversification in Central America, and Manduca appears to have subsequently colonized North and South America. Our phylogeny provides an important foundation for comparative studies of two model organisms and their relatives.