Station d'Ecologie Théorique et Expérimentale, Oula-Lab, CNRS, UMR 5321, 09200, Moulis, France.
Amphibian Evolution Lab, Biology Department, Vrije Universiteit Brussel, 2 Pleinlaan, B-1050, Brussels, Belgium.
Sci Rep. 2017 Jun 8;7(1):3041. doi: 10.1038/s41598-017-03355-y.
Hatching synchrony is wide-spread amongst egg-laying species and is thought to enhance offspring survival, notably by diluting predation risks. Turtle and snake eggs were shown to achieve synchronous hatching by altering development rates (where less advanced eggs may accelerate development) or by hatching prematurely (where underdeveloped embryos hatch concurrently with full-term embryos). In Natricine snakes, smaller eggs tend to slow down metabolism throughout incubation in order to hatch synchronously with larger eggs. To explore the underlying mechanism of this phenomenon we experimentally manipulated six clutches, where half of the eggs were reduced in mass by removing 7.2% of yolk, and half were used as the control. The former experienced higher heart rates throughout the incubation period, hatched earlier and produced smaller hatchlings than the latter. This study supports the idea that developmental rates are related to egg mass in snake eggs and demonstrates that the relationship can be influenced by removing yolk after egg-laying. The shift in heart rates however occurred in the opposite direction to expected, with higher heart rates in yolk-removed eggs resulting in earlier hatching rather than lower heart rates resulting in synchronous hatching, warranting further research on the topic.
卵生物种中广泛存在着孵化同步现象，这种现象被认为可以提高后代的存活率，特别是通过降低捕食风险。研究表明，龟和蛇类的卵通过改变发育速度（即让发育较慢的卵加速发育）或提前孵化（即让发育不完全的胚胎与足月胚胎同时孵化）来实现孵化同步。在蟒科蛇类中，较小的卵在孵化过程中通过降低新陈代谢速度来与较大的卵同步孵化。为了探究这种现象的潜在机制，我们实验性地处理了六个卵窝，其中一半卵通过去除 7.2%的蛋黄来减少质量，另一半作为对照。前者在整个孵化期间的心率更高，孵化更早，产生的幼体更小。这项研究支持了蛇卵的发育速度与卵质量有关的观点，并表明在产卵后去除蛋黄可以影响这种关系。然而，心率的变化方向与预期相反，去除蛋黄的卵的心率更高，导致更早孵化，而不是更低的心率导致同步孵化，这需要进一步研究。
