COS 280-4 - Pollination as a plant trait: major evolutionary patterns and environmental relationships of pollination across the angiosperms

Abstract: Flowers and floral traits such as pollination syndromes have often been overlooked in plant trait studies, despite the key role that flowers and pollination play in plant ecology and evolution. Floral traits are shaped by interactions with pollinators, and pollination often drives the speciation of flowering plants. Yet it is still unknown how the ancestral flower was pollinated, and how pollination has evolved through the history of the angiosperms. Most contemporary angiosperms are insect pollinated, but abiotic pollination by wind or water and vertebrate pollination by birds or mammals occurs in many lineages. Here we use a robust dated phylogeny and trait-independent species-level sampling across all families and major subfamilies of angiosperms to model the evolution of pollination modes. Using data on the pollination system or syndrome of 1160 species collated from primary literature we show that angiosperms were ancestrally insect pollinated. Insects have pollinated angiosperms for approximately 86% of angiosperm evolutionary history. Wind pollination evolved at least 42 times, with few reversals back to animal pollination. Transitions between insect and vertebrate pollination were more frequent: vertebrate pollination evolved at least 39 times from an insect pollinated ancestor with at least 26 reversals. The probability of wind pollination increases with habitat openness (measured by Leaf Area Index) and with distance from the equator. Our reconstruction of pollination across angiosperms sheds light on a key question in angiosperm macroevolution, highlighting the long history of interactions between insect pollinators and angiosperms still vital to global biodiversity today. Our approach also exemplifies the use of floral traits such as pollination syndromes in large scale studies, which hold great potential for addressing fundamental questions about the ecology and evolution of both plants and pollinators.