Molecular phylogenies of fig wasps: Partial cocladogenesis of pollinators and parasites

Abstract

Figs (Ficus spp., Moraceae) and their pollinating wasps form an obligate mutualism, which has long been considered a classic case of coevolution and cospeciation. Figs are also exploited by several clades of nonpollinating wasps, which are parasites of the mutualism and whose patterns of speciation have received little attention. We used data from nuclear and mitochondrial DNA regions to estimate the phylogenies of 20 species of Pleistodontes pollinating wasps and 16 species of Sycoscapter nonpollinating wasps associated with Ficus species in the section Malvanthera. We compare the phylogenies of 15 matched Pleistodontes/Sycoscapter species pairs and show that the level of cospeciation is significantly greater than that expected by chance. Our estimates of the maximum level of cospeciation (50 to 64% of nodes) are very similar to those obtained in other recent studies of coevolved parasitic and mutualistic associations. However, we also show that there is not perfect congruence of pollinator and parasite phylogenies (for any substantial clade) and argue that host plant switching is likely to be less constrained for Sycoscapter parasites than for Pleistodontes pollinators. There is perfect correspondence between two terminal clades of two sister species in the respective phylogenies, and rates of molecular evolution in these pairs are similar. © 2001 Academic Press.