Temporal Lags and Overlap in the Diversification of Weevils and Flowering Plants: Recent Advances and Prospects for Additional Resolution

Abstract

Weevils (superfamily Curculionoidea) are by all accounts unusually successful. There are ~62,OOO described extant species in 7 families1 and ~5,800 genera. However; most weevil species remain undescribed (Oberprieler et aI., 2007). More than 80% of weevil species belong to the family Curculionidae (Anderson, 1995). Weevils collectively feed on nearly all kinds of plants and plant parts, but most living species are specialist herbivores on angiosperms (flowering plants). All living weevil families are known from the Cretaceous fossil record (Oberprieler et aI., 2007). The earliest unequivocal fossil weevils, representatives of the family Nemonychidae, appear in the Late Jurassic (Gratshev & Zherikhin, 2003). These early weevils probably developed in the reproductive structures of gymnosperms, most likely conifers or cycads (Kuschel, 1983; Farrell, 1998; McKenna et aI., 2009). Host shifts to angiosperms have been shown to be associated with increased taxonomic diversity in weevils (Farrell, 1998). However, until recently. the role of angiosperms in weevil macroevolution was difficult to interpret due to the lack of a well-resolved higher-level phylogeny and corresponding methodologically robust molecular timetree for weevils. McKenna etal. (2009) presented a large-scale molecular phylogeny and timetree for weevils based on ~8 kilo bases of ONA sequence data from six genes (185,285, arginine kinase, elongation factor i-a, cytochrome oxidase I, and 165). These data were obtained from a sample of 135 weevil genera representing all families and subfamilies and most major tribes of the family Curculionidae. Outgroups included exemplars from seven subfamilies of Chrysomeloidea (the weevil sister group) (Farrell, 1998; Marvaldi et aI., 2009), and the rather more distantly related cucujoid Ericmodes sylvaticus (Philippi) (Protocucujidae). Node ages estimated from combined analyses of molecular and fossil data were consistent with diversification of weevils into most extant families on gymnosperms in the Jurassic, and colonization of early crown-group angiosperms during the subsequent Early Cretaceous. Massive diversification of angiosperm-as-