Effects of incubation temperature on hatchling phenotypes in an oviparous lizard with prolonged egg retention: are the two main hypotheses on the evolution of viviparity compatible?
Effects of incubation temperature on hatchling phenotypes in an oviparous lizard with prolonged egg retention: are the two main hypotheses on the evolution of viviparity compatible?
复制标题
DOI：
10.1016/j.zool.2009.05.001
复制
发表时间：
2010
期刊：
影响因子：
2
通讯作者：
T. Rodríguez-Díaz;Félix González;X. Ji;F. Braña
中科院分区：
文献类型：
--
作者：
T. Rodríguez-Díaz;Félix González;X. Ji;F. Braña
几种蜥蜴物种的雌性在怀孕期间会改变体温，这可能与幼体表型的优化有关。我们研究了西班牙北部胎生动物 Zootoca vivipara (Jacquin, 1797)（有鳞：蜥蜴科）卵生群体中怀孕雌性与雄性和非妊娠雌性选择的温度的变化，并研究了孵化温度对幼体表型变化的影响。活跃在野外的怀孕雌性的泄殖腔温度低于雄性和未怀孕雌性的温度，以及在实验室创建的热梯度中选择的温度（平均值±标准差：怀孕雌性为32.33±1.27°C；雄性和非怀孕雌性为34.05±1.07°C）。通过在五个恒定温度（21、25、29、32 和 34°C）下孵化鸡蛋来评估温度的影响。孵育时间随着温度升高而缩短，遵循负指数函数。孵化温度也会影响幼体的形态：在 34°C 下孵化的幼体比其他温度下孵化的幼体头部较短。 34°C 下的存活率 (58%) 显着低于其他温度下的存活率（平均 93%）。根据对胎生进化的母体操纵假说的预测，怀孕的雌性会选择较低的体温，接近优化孵化表型的温度。根据寒冷气候假说的预测，怀孕雌性对偏好温度的改变只会导致孵化时间非常短的延迟（如果有的话），并且由于怀孕雌性选择的温度远高于胎生珠母贝自然巢中记录的平均温度，因此卵保留大大缩短了孵化时间。我们的实验结果表明，关于胎生进化的两个主要假设在我们的研究模型中是兼容的。
Females of several lizard species modify their body temperature during pregnancy, probably in connection with the optimisation of hatchling phenotypes. We studied variations in the temperature selected by gravid females compared with those selected by males and non-gravid females in an oviparous population of Zootoca vivipara (Jacquin, 1797) (Squamata: Lacertidae) of Northern Spain and examined the effects of incubation temperature on the phenotypic variation of hatchlings. Cloacal temperatures of gravid females active in the field were lower than those of males and non-gravid females, as well as the temperatures selected in a thermal gradient created in the laboratory (mean±s.d.: 32.33±1.27°C for gravid females; 34.05±1.07°C for males and non-gravid females). Effects of temperature were assessed by incubating eggs at five constant temperatures (21, 25, 29, 32 and 34°C). Incubation time decreased as temperature increased, following a negative exponential function. Incubation temperatures also affected the hatchlings’ morphology: hatchlings incubated at 34°C had shorter heads than those from other temperatures. Survival at 34°C (58%) was significantly lower than at the other temperatures (mean 93%). Pregnant females select lower body temperature, approaching the temperatures that optimise hatchling phenotypes, according to predictions of the maternal manipulation hypothesis on the evolution of viviparity. The shift in preferred temperature by pregnant females would result in only a very short delay, if any, of hatching time and, because the temperature selected by pregnant females is much higher than average temperatures recorded in natural nests of Z. vivipara, egg retention considerably shortens incubation time, according to predictions of the cold-climate hypothesis. Our experimental results indicate that the two main hypotheses on the evolution of viviparity are compatible in our study model.