Phylogenetic relationships, historical biogeography and character evolution of fig-pollinating wasps

Nucleotide sequences from the cytochrome oxidase I (COI) gene were used to reconstruct phylogenetic relationships among 15 genera of fig-pollinating w asps. We present evidence supporting broad-level co-cladogenesis with respe ct to most but not all of the corresponding groups of figs. Using fossil ev idence for calibrating a molecular clock for these data, we estimated the o rigin of the fig-wasp mutualism to have occurred ca. 90 million years ago. The estimated divergence times among the pollinator genera and their curren t geographical distributions corresponded well with several features of the break-up of the southern continents during the Late Cretaceous period. We then explored the evolutionary trajectories of two characteristics that hol d profound consequences for both partners in the mutualism: the breeding sy stem of the host (monoecious or dioecious) and pollination behaviour of the wasp (passive or active). The fig-wasp mutualism exhibits extraordinarily long-term evolutionary stability despite clearly identifiable conflicts of interest between the interactors, which are reflected by the very distinct variations found on the basic mutualistic theme.