Meeting Abstract
Synchronous hatching is a form of environmentally cued hatching (ECH) which allows embryos to alter hatching time in relation to the environment through phenotypic plasticity. In some turtles, synchronous hatching results from metabolic compensation or early hatching, and has evolved to reduce variation in clutch incubation time and increase an individual’s chance of survival. Hormones likely play a critical role in enabling metabolic compensation and early hatching. Thyroid hormones and glucocorticoids regulate embryogenesis and are vital during birth/hatching events in many species. I compared the metabolic and endocrine mechanisms of hatching synchrony in freshwater turtles. Hormone analyses indicated there was no difference in triiodothyronine (T3) and corticosterone concentrations during asynchronous development but concentrations increased in the yolk of the developing embryos towards the end of incubation, which coincides with hatching. There was a clear physiological response to exogenous T3 applications, which caused neonates to hatch earlier than expected but with no developmental or metabolic costs. These hormones might not regulate metabolic compensation, but they are likely important for synchronous hatching. Comparing the mechanisms used to synchronously hatch will further improve the understanding of the different ways in which ECH has evolved in reptiles.
