Natatanuran frogs used the Indian Plate to step-stone disperse and radiate across the Indian Ocean

【摘要】：The breakup of Gondwana,in the Late Mesozoic,triggered major biotic exchanges between Laurasia and Gondwana that continue to influence modern distributions of many taxa.Concerning drift of the Indian Plate,the traditional view has this landmass acting as an isolated biotic ferry in the Indian Ocean,carrying Gondwanan biodiversity to Asia in the Early Tertiary;and many biogeographic studies have relied on this assumption.However,the exact route of the Indian Plate,and its proximity to other continents(notably Africa),remains contentious.Similarly,debate continues about possible landbridges linking Antarctica-Australia-New Guinea to either the Indian Plate,or Madagascar,during the Late Cretaceous.Using the near-cosmopolitan distribution of Natatanuran frogs,we here integrate phylogenomic data,biogeographic reconstruction,and molecular dating methods to resolve the spatiotemporal diversification of ranoid frogs between Laurasia and Gondwana,and examine support for alternative biogeographic hypotheses.Unexpectedly,our results strongly support two major stepping-stone dispersals between 88–55 My via the Indian Plate:1) dispersal from Africa to Asia,and 2) dispersal from Asia to Madagascar.This is the first case of extant taxa using the Indian Plate as a stepping stone to disperse between Africa,Asia and Madagascar;and supports a close biogeographic association between Africa and the India Plate in the Late Cretaceous.We also find no evidence of Natatanuran exchanges between Antarctica-Australia-New Guinea and either India or Madagascar before the Eocene,arguing against hypothetical landbridges.Rather,we find two lineages independently dispersed from Asia to Australia-New Guinea much later,during the Neogene.