The dual role of the angiosperm radiation on insect diversification

Abstract

Most of the animal pollination is realized by insects, interactions between them and flowering plants have been hypothesized to be important drivers of diversification. Yet, there is weak support for coevolutionary diversification in plant-pollinator interactions. Macroevolutionary studies on insect and plant diversities support the hypothesis that angiosperms evolved after an insect diversity peak in the Early Cretaceous, suggesting that gymnosperm pollinators may have been accessible for angiosperms when they evolved. We examined fossil and phylogenetic evidence documenting this hypothesis and provide new clues on the impact of angiosperm radiation on insect diversification. Using the family-level fossil record of insects and a Bayesian process-based approach, we estimated diversification rates and the role of six different variables on insect macroevolutionary history. We found that, among the six tested variables, angiosperms had a dual role that has changed through time with an attenuation of insect extinction in the Cretaceous and a driver of insect origination in the Cenozoic. However, increasing insect diversity, spore plants and global temperature also showed strong positive correlation with both origination and extinction rates of insects, suggesting that different drivers had important effect on insect evolution, not just angiosperms, which would deserve further studies.