Effects of semi-constant temperature on embryonic and hatchling phenotypes of six-tubercled Amazon River turtles, Podocnemis sextuberculata

Purpose: We evaluated how constant incubation temperatures affect life-history traits pre-hatching and post-hatching of the six-tubercled Amazon River turtle, Podocnemis sextuberculata.
Methods: We incubated eggs from natural nests at ten semi-constant temperatures between 22.26±1.01°C and 37.37±0.38°C (2013) and at six temperatures between 25.75±0.22°C and 36.17±0.15°C (2016). In 2013, we raised hatchling for 90 days to evaluate effects of temperature on early hatchling growth. We evaluated maternal effects in 2016.
Results: P. sextuberculata displays temperature-dependent sex determination and produces males at colder and females at warmer temperatures (TSD Ia). The estimated pivotal temperature was 33.73 ± 0.15°C and the transitional range of temperatures (TRT) 1.16 ± 0.59°C. Semi-constant temperatures below 26°C and above 38°C were lethal. Intermediate temperatures (32.25°C and 31.5°C, respectively) were optimal for hatching success and produced larger hatchlings that grew slower ea...

研究目的：本研究旨在评估恒定孵化温度对六瘤亚马逊河龟（Podocnemis sextuberculata）的胚胎期与出壳后生活史特征的影响。
研究方法：2013年，我们将自然巢穴中的龟卵置于10个半恒定温度梯度下孵化，温度区间为22.26±1.01℃至37.37±0.38℃；2016年则设置了6个温度梯度，区间为25.75±0.22℃至36.17±0.15℃。2013年，我们将孵化出的幼龟饲养90天，以探究温度对幼龟早期生长的影响；2016年则开展了母体效应相关研究。
研究结果：六瘤亚马逊河龟（Podocnemis sextuberculata）存在温度依赖型性别决定（temperature-dependent sex determination, TSD）Ia型，即低温环境下产生雄性个体，高温环境下产生雌性个体。其临界温度估计为33.73±0.15℃，温度过渡区间（transitional range of temperatures, TRT）为1.16±0.59℃。半恒定温度低于26℃或高于38℃的环境均具有致死性。中等温度（分别为32.25℃与31.5℃）最利于提升孵化成功率，可培育出体型更大但生长速度较慢的幼龟...