CONVERGENT EVOLUTION OF AGAONINE AND SYCOECINE (AGAONIDAE, CHALCIDOIDEA) HEAD SHAPE IN RESPONSE TO THE CONSTRAINTS OF HOST FIG MORPHOLOGY

Similar morphological adaptations have arisen independently across sep arate lineages within the fig wasps (Agaonidae, Chalcidoidea, Hymenopt era) in response to the extreme selective pressure provided by the mor phological constraints of their host fig trees (Ficus, Moraceae). Evid ence is forwarded that supports the convergence of female head shape b etween two distinct fig wasp lineages, the Agaoninae (pollinators) and Sycoecinae (non-pollinators), utilizing the same host Ficus species ( section Gagolychia). In contrast to the vast majority of the non-polli nating fig wasps, that oviposit from the outside of the fig, the Agaon inae and Sycoecinae must negotiate the fig ostiole for internal ovipos ition, with the result that these independent lineages are simultaneou sly exposed to the selective pressure imposed by ostiolar morphology. Selection will favour a head shape that facilitates successful penetra tion of the fig cavity and this has resulted in the evolution of simil ar head shapes in the two lineages. Female head shape in both subfamil ies was found to correlate with fig size, with elongate heads associat ed with large fig size. Given that ostiole bract arrangement is unifor m within section Galoglychia, it appears that ostiole length may be th e main factor contributing to head shape determination. The high degre e of co-adaptation of head shape suggests that both the Sycoecinae and Agaoninae have coevolved with their host Ficus species.