Early diversifications of angiosperms and their insect pollinators: were they unlinked?

Abstract

The present-day ubiquity of angiosperm-insect pollination has led to the hypothesis that these two groups coevolved early in their evolutionary history. However, recent fossil discoveries and fossil-calibrated molecular dating analyses challenge the notion that early diversifications of angiosperms and insects were inextricably linked. In this article, we examine (i) the discrepancies between dates of emergence for angiosperms and major clades of insects; (ii) the long history of gymnosperm-insect pollination modes, which likely shaped early angiosperm-insect pollination mutualisms; and (iii) how the K-Pg (Cretaceous-Paleogene) mass extinction event was vital in propelling modern angiosperm-insect mutualisms. We posit that the early diversifications of angiosperms and their insect pollinators were largely decoupled until the end of the Cretaceous.