Girondot Marc, Monsinjon Jonathan, Guillon Jean-Michel
Ecologie, Systématique, Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400 Orsay, France.
J Therm Biol. 2018 Apr;73:32-40. doi: 10.1016/j.jtherbio.2018.02.006. Epub 2018 Feb 10.
The sexual phenotype of the gonad is dependent on incubation temperature in many turtles, all crocodilians, and some lepidosaurians. At hatching, identification of sexual phenotype is impossible without sacrificing the neonates. For this reason, a general method to infer sexual phenotype from incubation temperatures is needed. Temperature influences sex determination during a specific period of the embryonic development, starting when the gonad begins to form. At constant incubation temperatures, this thermosensitive period for sex determination (TSP) is located at the middle third of incubation duration (MTID). When temperature fluctuates, the position of the thermosensitive period for sex determination can be shifted from the MTID because embryo growth is affected by temperature. A method is proposed to locate the thermosensitive period for sex determination based on modelling the embryo growth, allowing its precise identification from a natural regime of temperatures. Results from natural nests and simulations show that the approximation of the thermosensitive period for sex determination to the middle third of incubation duration may create a quasi-systematic bias to lower temperatures when computing the average incubation temperature during this period and thus a male-bias for sex ratio estimate.
在许多龟类、所有鳄目动物以及一些有鳞目动物中，性腺的性别表型取决于孵化温度。在孵化时，若不牺牲新生个体就无法确定其性别表型。因此，需要一种从孵化温度推断性别表型的通用方法。温度在胚胎发育的特定时期影响性别决定，这个时期从性腺开始形成时起。在恒定的孵化温度下，这个性别决定的热敏期（TSP）位于孵化期的中间三分之一阶段（MTID）。当温度波动时，由于胚胎生长受温度影响，性别决定的热敏期位置可能会从MTID发生偏移。本文提出了一种基于胚胎生长建模来确定性别决定热敏期的方法，从而能够从自然温度状态中精确识别该时期。来自自然巢穴和模拟的结果表明，在计算该时期的平均孵化温度时，将性别决定热敏期近似为孵化期的中间三分之一阶段可能会对较低温度产生准系统性偏差，进而导致性别比例估计出现雄性偏差。
