Evolutionary implications of a deep-time perspective on insect pollination

Plant pollination by insects represents one of the most transformative and iconic ecological relationships in the natural world. Despite tens of thousands of papers, as well as numerous books, on pollination biology published over the past 200 years, most studies focused on the fossil record of pollinating insects have only been published in the last few decades, and this field is still undergoing major developments. Current palaeontological evidence indicates that pollinating insects were diverse and participated in the reproduction of different gymnosperm lineages long before their association with flowering plants (angiosperms). However, since much of this literature remains unfamiliar to many scientists working on extant plant-pollinator interactions, as well as the wider public, the notion that insect pollination began with the origin of angiosperms is still widespread. Herein we highlight how all the known insect orders with extant and/or extinct pollinator representatives radiated long before the evolution of flowering plants. We also illustrate the changing composition of the insect pollinator fauna through time, reflecting the different nature of these communities compared to those existing today. Addressing plant pollination by insects from a perspective skewed towards present-day biological groups, patterns, and processes risks missing an important deep-time evolutionary component. Our conclusions show that the fossil record is fundamental to elucidating the origin and evolution of insect pollination, as well as informing on present-day plant-pollinator interactions.