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Phylogeographic structure in the bogus yucca moth Prodoxus quinquepunctellus: comparisons with coexisting pollinator yucca moths.
ALTHOFF, DAVID1, GROMAN, JOSHUA1,2, SEGRAVES, KARI1, PELLMYR, OLLE1, 1 2
ABSTRACT- The pollination mutualism between yucca moths and yuccas highlights the potential importance of host plant specificity in insect diversification. Historically, one pollinator moth species, Tegeticula yuccasella, was believed to pollinate most yuccas, but recent ecological and phylogenetic studies have revealed that it is a complex of at least 13 distinct species, eight of which are specific to one yucca species. Like the pollinators, moths in the closely related genus Prodoxus also specialize on yuccas, but they do not pollinate and their larvae feed on different plant parts. We examined the phylogeographic structure of P. quinquepunctellus across its range to compare patterns of diversification with its six coexisting pollinator species. Morphometric and mtDNA cytochrome oxidase I sequence data indicated that P. quinquepunctellus contains two species. There was a deep division between moth populations in the eastern and western United States, with limited sympatry in central Texas, and a lesser division between western populations on the Colorado Plateau and those elsewhere. In comparison, the six pollinator species comprise three lineages, one eastern and two western. A pollinator species endemic to the Colorado Plateau has evolved in both western lineages. The east-west division and the separate evolution of two Colorado Plateau pollinator species suggest similar biogeographic factors have influenced diversification in both Tegeticula and Prodoxus. For the pollinators, however, each lineage has produced a monophagous species, a pattern not seen in P. quinquepunctellus.
KEY WORDS: specialization, phylogeography, speciation, biogeography