An integrated approach to studying the coevolution of the Fig and Fig-Wasp Mutualism

Abstract

Mutualism is ubiquitous and has had significant consequences on the diversity and organization of life. In flowering plants, mutualistic interactions—particularly those with animal pollinators—drive angiosperm diversification. For example, the 800+ species of fig trees (genus Ficus) have evolved elaborate floral fragrances and morphological traits to attract species-specific fig wasp pollinators (family Agaonidae, superfamily Chalcidoidea). Mutualistic interactions are especially prevalent drivers of diversification in co-evolving species, such as the fig and fig-wasp pollination mutualism, because each species reciprocally imposes strong selective pressures on the other for reproductive success. Indeed, figs and their pollinating wasps are a textbook example of an obligate mutualism in which each partner is entirely dependent on the other for reproductive success. Given these interactions’ ecological and evolutionary importance, my dissertation research has used complementary ecological and genetic approaches to understand their formation and maintenance at multiple biological scales. I have investigated barriers to dispersal and gene flow at the population level, leading to geographic differentiation and potential speciation in fig pollinators. At the community level, I have investigated the radiation of fig wasp pollinators across widely distributed figs species and pollinator-sharing between co-occurring fig species. Finally, at the species level, I have investigated the role of floral fragrance in maintaining pollinator specificity by investigating gene flow between hybridizing Ficus lineages.