The Oligocene Indo-Asian Faunal Interchange

Diversification of rhacophorid frogs provides evidence for accelerated faunal exchange between India and Eurasia during the Oligocene

Authors:

1. Jia-Tang Li (a,b)
2. Yang Li (a,c)
3. Sebastian Klaus (d)
4. Ding-Qi Rao (a)
5. David M. Hillis (e)
6. Ya-Ping Zhang (a,f)

Affiliations:

a. State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China

b. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China

c. College of Life Sciences, Sichuan University, Chengdu 610064, China

d. Department of Ecology and Evolution, Goethe University, 60438 Frankfurt am Main, Germany

e. Section of Integrative Biology and Center for Computational Biology and Bioinformatics, University of Texas at Austin, Austin, TX 78712

f. Laboratory for Conservation and Utilization of Bioresources, Yunnan University, Kunming 650091, China

Abstract:

The accretion of the Indian subcontinent to Eurasia triggered a massive faunal and floral exchange, with Gondwanan taxa entering into Asia and vice versa. The traditional view on the Indian–Asian collision assumes contact of the continental plates during the Early Eocene. Many biogeographic studies rely on this assumption. However, the exact mode and timing of this geological event is still under debate. Here we address, based on an extensive phylogenetic analysis of rhacophorid tree frogs, if there was already a Paleogene biogeographic link between Southeast Asia and India; in which direction faunal exchange occurred between India and Eurasia within the Rhacophoridae; and if the timing of the faunal exchange correlates with one of the recently suggested geological models. Rhacophorid tree frogs showed an early dispersal from India to Asia between 46 and 57 Ma, as reconstructed from the fossil record. During the Middle Eocene, however, faunal exchange ceased, followed by increase of rhacophorid dispersal events between Asia and the Indian subcontinent during the Oligocene that continued until the Middle Miocene. This corroborates recent geological models that argue for a much later final collision between the continental plates. We predict that the Oligocene faunal exchange between the Indian subcontinent and Asia, as shown here for rhacophorid frogs, also applies for other nonvolant organisms with an Indian–Asian distribution, and suggest that previous studies that deal with this faunal interchange should be carefully reinvestigated.