Planktivores as trophic drivers of global coral reef fish diversity patterns

Significance For decades, marine biogeographers have been intrigued by the origins of the Indo-Australian Archipelago (IAA) biodiversity hotspot. Yet one important ecological factor remained unexplored: the trophic status of species across the diversity gradient. Here we show how trophic identity crucially underpins coral reef fish diversity patterns via a disproportional concentration of plankton-feeding species in the IAA. This planktivore hotspot, however, vanishes abruptly away from the IAA. Over the recent geological past, planktivorous reef fishes successfully partitioned constant resources promoted by unique oceanographic conditions in the IAA while likely undergoing disproportional extinctions in peripheral regions. This intriguing case of ecological success intertwined with differential extinctions offers key insights into the origins of biodiversity gradients.