Hatching plasticity in a Southeast Asian tree frog
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Hatching, the life history switch point between embryonic and larval or subadult stages, has traditionally been regarded as a fixed event in an organism’s development. This notion has been challenged by reports of environmentally cued hatching in recent years, which show embryos improve fitness by hatching in response to mortality risks. Here, we present evidence of accelerated hatching due to predation at two points during embryonic development in Chiromantis hansenae. Young embryos (0 day old) exposed to simulated predation hatched earlier compared to undisturbed clutches. Old embryos (4 days old) subjected to direct katydid predation had more immediate responses, hatching <1 h after predation on average. Hatching time was not correlated with female frog size, egg attendance time, or other predator cues. Results confirm predator-cued hatching in a new family of amphibians and support hatching plasticity being a widespread and potentially ancestral condition. We suggest mechanisms and ecological basis of cue transmission and response in C. hansenae and point out potential further research.
KeywordsEnvironmentally cued hatching Predator cues Rhacophoridae Chiromantis Katydid Hexacentrus
We thank Director T. Artchawakom and the entire staff of Sakaerat for their unwavering logistic support and hospitality. We thank K.M. Warkentin for early discussions, directions, and comments on the manuscript and L.R. Carrasco for advice on statistical analyses. We are grateful to S.D. Howard and three anonymous reviewers for their constructive suggestions. Collection of field data was made possible by the wonderful assistance of A.F. McNear, J.J. Reinig, and J.S. Sherrock. Katydid species was identified by M.K. Tan and illustrations were made by A.K.S. Wee. Funding support was provided by the Ministry of Education and the National University of Singapore (Grant # R-154-000-383-133) and the Singapore International Graduate Award.
All experiments were approved by the Institutional Animal Care and Use Committee at National University of Singapore (Protocol B11/12). Frog handling was done with care and all animals were returned to their original locations as soon as the experiments concluded. In addition, work at the Sakaerat Environmental Research Station was approved by the National Research Council of Thailand (Project I.D.: 2010/063).
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