Abstract
One of the greatest challenges in the study of coevolution, indeed, for biology in general, is to understand how complex traits of multiple functions have diversified and codiversified across interacting lineages and geographic ranges. The fig-wasp pollination mutualism provides a unique opportunity to examine fundamental processes of coevolution, namely, reciprocal adaptation where interacting partners are the agents of selection. In this thesis, we explore the forces governing geographic variation in plant-insect communication and their biological consequences, focusing on the relationship between receptive fig odor and host plant and pollinating fig wasp genetic structure and behaviour. Integrating inflorescence odors, pollination ecology and population genetics in three widely distributed Ficus species, namely Ficus hirta, Ficus hispida, and Ficus triloba, the results show that geographic variation in receptive fig odors corresponds to plant genetic structure and not to pollinator genetic structure. Geographic variation of receptive fig odors affects the insect’s capacity to locate non-local receptive figs as the insects are adapted to the local odors. Nevertheless, the olfactive signaling of related Ficus species may overlap so that in some locations, pollinators may be attracted by non-host receptive figs. This dissertation explores previously unstudied aspects of the fig and fig wasp mutualism and can provide new perspectives for future study of this iconic and ecologically important association. More generally, the results provide insights into co-evolutionary processes governing plant-insect communication in brood site pollination mutualisms, a pollination system whose frequency in plants is largely underestimated.