Phylogenetic relationships of fig wasps pollinating functionally dioeciousFicus based on mitochondrial DNA sequences and morphology

The obligate mutualism between pollinating fig wasps in the family Agaonida e (Hymenoptera: Chalcidoidea) and Ficus species (Moraceae) is often regarde d as an example of coevolution but little is known about the history of the interaction, and understanding the origin of functionally dioecious fig po llination has been especially difficult. The phylogenetic relationships of fig wasps pollinating functionally dioecious Ficus were inferred from mitoc hondrial cytochrome oxidase gene sequences (mtDNA) and morphology. Separate and combined analyses indicated that the pollinators of functionally dioec ious figs are not monophyletic. However, pollinator relationships were gene rally congruent with host phylogeny and support a revised classification of Ficus. Ancestral changes in pollinator ovipositor length also correlated w ith changes in fig breeding systems. In particular, the relative elongation of the ovipositor was associated with the repeated loss of functionally di oecious pollination. The concerted evolution of interacting morphologies ma y bias estimates of phylogeny based on female head characters, but homoplas y is not so strong in other morphological traits. The lesser phylogenetic u tility of morphology than of mtDNA is not due to rampant convergence in mor phology but rather to the greater number of potentially informative charact ers in DNA sequence data; patterns of nucleotide substitution also limit th e utility of mtDNA findings. Nonetheless, inferring the ancestral associati ons of fig pollinators from the best-supported phylogeny provided strong ev idence of host conservatism in this highly specialized mutualism.