Meeting Abstract

S8.4  Thursday, Jan. 6  Evidence for Environmentally-cued Hatching in Reptiles DOODY, J. Sean; Monash University, Melbourne, Australia sean.doody@monash.edu

Reptilian embryos typically suffer high mortality from both biotic and abiotic sources (e.g., predation, pathogens, flooding, desiccation). When these threats are imminent embryos can escape the danger by accelerating or delaying hatching. Herein I review published and unpublished reports of environmentally-cued hatching (ECH) in reptiles. Few studies have explored ECH in reptiles: it is reported to occur in lizards (5 spp.), turtles (4 spp.), and crocodilians (1 spp.). Reptiles can hatch early in response to flooding, predation, or pathogens. Although a hypoxic cue has been linked to hatching during flooding, evidence for predation triggering early hatching is indirect: vibrations can cause early hatching in lizards, turtles, and crocodilians. Sibling communication is apparently used to accelerate hatching in turtles (via vibrations) and crocodilians (via acoustics and vibrations). In these cases ECH may be a mechanism to achieve hatching synchrony. The most complex example involves different spatial scales: pig-nosed turtle embryos (1) delay hatching for weeks during the dry season; (2) hatch minutes to days early in response to wet season flooding (hypoxia); and accelerate hatching further via sibling vibrations. ECH may be ubiquitous within or among reptile groups, and our knowledge of ECH in reptiles lags behind that for other taxa. Novelty is perhaps limited to evidence for sibling communication in response to abiotic risk. However, the context and costs-benefits of early hatching in reptiles may differ from those in other taxa in certain ways. For example, early hatching skinks burst from the egg and immediately run vigorously, presumably because their egg predators are often also predators of their hatchlings (e.g., in species with complex life cycles predator type often differs between the terrestrial eggs and aquatic larvae). The paucity of information on ECH in reptiles suggests that new discoveries await us.