Abstract

Plants that provide food and housing to animals in return for defense against enemies are classic examples of mutualistic partnerships in nature. Here, we show that the evolution of such plant-animal mutualisms also can lead to a trajectory of accelerated accumulation of plant species in the lineages that participate in these cooperative interactions. We found that the evolution of plant organs (extrafloral nectaries) that facilitate mutualisms with animal defenders was repeatedly followed by increased rates of diversification across distantly related plant lineages. These results suggest that by enabling ecological interactions with animals, the convergent evolution of relatively simple glands changed the course of plant evolution toward greater protection from pests and accelerated the generation of biodiversity.