Acknowledgements

We thank Ilham and Erick Mandelson for the unwavering nightly field work, and Ingo Grass for critically constructive comments on the manuscript draft. Arne Wenzel and Xueqing He provided valuable comments. This study was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)–project number 192626868–SFB 990 in the framework of the collaborative German-Indonesian research project CRC990. We declare that the authors have no conflicts of interest.