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

Figs (Ficus spp., Moraceae) and their pollinating wasps form an obligate mu tualism, which has long been considered a classic case of coevolution and c o-speciation. Figs are also exploited by several clades of nonpollinating w asps, which are parasites of the mutualism and whose patterns of speciation have received little attention. We used data from nuclear and mitochondria l DNA regions to estimate the phylogenies of 20 species of Pleistodontes po llinating wasps and 16 species of Sycoscapter nonpollinating wasps associat ed with Ficus species in the section Malvanthera. We compare the phylogenie s of 15 matched Pleistodontes/Sycoscapter species pairs and show that the l evel of cospeciation is significantly greater than that expected by chance. Our estimates of the maximum level of cospeciation (50 to 64% of nodes) ar e very similar to those obtained in other recent studies of coevolved paras itic and mutualistic associations. However, we also show that there is not perfect congruence of pollinator and parasite phylogenies (for any substant ial clade) and argue that host plant switching is likely to be less constra ined 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 pa irs are similar. (C) 2001 Academic Press.