A phylogeographical framework for Zhangixalus gliding frogs, with insight on their plasticity of nesting behaviour

Old World tree frogs from the family Rhacophoridae, one of the most species-rich groups of amphibians worldwide, are becoming a model in ecological and evolutionary research, notably for their tremendous diversity of breeding systems. In this study, we provide the most comprehensive temporally and spatially explicit phylogeographical framework for the tropical neo-genus Zhangixalus, with a specific focus on the evolution of inter- and intraspecific polymorphism in their egg-laying strategies. We combined similar to 500 sequences spanning similar to 4 kb of mitochondrial genes, representative of nearly all known Zhangixalus species from 373 localities. We recovered a robust timetree featuring similar to 60 phylogeographical lineages assigned to 36 taxa, illustrating a vast under-appreciation of the diversity of the genus. Patterns of diversification were intimately linked to climatic trends since the Mid-Miocene, leading to a remarkable biogeographical scenario for the onset of Taiwanese diversity. Finally, in contrast to the macro-evolution of conserved breeding strategies in rhacophorids, the striking variation of nesting behaviour documented across Zhangixalus species, whereby foamy egg nests are alternatively fossorial, deposited on the edge of the water or suspended on the overhanging vegetation, seems to have evolved rapidly from arboreal ancestors in all major clades, implying micro-evolutionary processes and/or phenotypic plasticity.