Title

Molecular systematics and the macroevolution of host plant use in the endophagous moth genus Papaipema Smith, 1899 (Lepidoptera: Noctuidae)

Date of Completion

January 1999

Keywords

Biology, Ecology|Biology, Entomology

Degree

Ph.D.

Abstract

DNA sequence data from nuclear and mitochondrial genes are used to construct a, phylogenetic hypothesis for the extant species of Papaipema (Lepidoptera: Noctuidae: Apameini), an endophagous moth genus whose members have specialized in a taxonomically diverse array of angiosperm host plants. The expanded analysis, designed in part to test the monophyly of the genus, includes members of ten other endophagous apameine genera: Hydraecia (in which Papaipema was originally described as a subgenus); Gortyna; Parapamea; Amphipoea; Apamea; Meropleon; Macronoctua; Iodopepla; Franclemontia; and Bellura. Parsimony-based analyses reveal a monophyletic Papaipema, Hydraecia, and Apamea, and a polyphyletic Amphipoea. Most parsimonious optimizations of host plant family associations within Papaipema indicate a “pattern” of host shifts that are drastic with respect to host plant taxonomic affinity. None of the major “groups” of Papaipema associated with a single plant family are monophyletic; and there exists no plant family associated with two or more Papaipema species for which that association evolved but a single time. To the extent host plant associations are conserved phylogenetically, reversals appear in every case. Although this system is limited with respect to its ability to test Berenbaum's (1981, 1983) coevolutionary hypotheses regarding the role of coumarin compounds as mediators of plant-herbivore evolution, one aspect of that hypothesis withstands testing, namely that association with plants defended by hydroxycoumarins preceded that with plants defended by furanocoumarins. When mapped onto the “pruned” cladogram summarizing the relationships among the apameine genera studied, a transformation series in the stage at diapause is evident, with mature larval overwintering preceding young larval overwintering preceding overwintering as eggs. That last coincides with the clade [[Hydraecia + Amphipoea] + [[Gortyna + Macronoctua] + [Parapamea + Papaipema]]. The members of this clade, including Papaipema, are also primarily associated with dicotyledonous plants, an association that can have evolved once or three times depending on parsimony optimization. It is proposed that endophagous feeding arose following the evolution of monocot feeding in this group, and was in turn followed by sequential diapause shifts that ultimately led to the colonization of a wide host plant spectrum. ^