Hatching plasticity in a Southeast Asian tree frog.

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. [ABSTRACT FROM AUTHOR]