Warner Daniel A, Mitchell Timothy S, Janzen Fredric J
Department of Biological Sciences, Auburn University, Auburn, Alabama, USA.
Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, Iowa, USA.
Integr Zool. 2025 Jul;20(4):883-893. doi: 10.1111/1749-4877.12890. Epub 2024 Sep 3.
Rising global temperatures have a wide range of effects at organismal, population, and ecosystem levels. Increased winter temperatures are expected to alter the energetics of species that are dormant during this time. Hatchling painted turtles (Chrysemys picta) spend their first ∼8 months in shallow nests on land, where they putatively rely on residual yolk reserves to fuel energetic demands during this period of inactivity before they emerge in the spring. We performed a laboratory experiment to characterize changes in residual yolk quantity in hatchling C. picta and experimentally tested the effect of temperature on residual yolk, hatchling size, and survival over the winter brumation period. We manipulated winter nest temperature by simulating two natural thermal regimes ("low" vs "high" treatments) and one regime that approximates warmer temperatures expected by 2100 ("future" treatment). Because high temperature increases metabolism, we predicted that the future temperature treatment would decrease the amount of residual yolk remaining by the end of winter and reduce hatchling mass and survival. Residual yolk over winter did not differ from that before winter, and the temperature had no effect on the quantity of residual yolk or hatchling survival by the following spring. However, hatchlings that experienced future temperatures lost more mass over winter than those from the other treatments. These results correspond with previous work indicating that residual yolk does not fuel the energetic needs of hatchlings during winter. The effect of future warming temperatures on body mass may have negative consequences during energetically demanding activities during spring emergence and dispersal.
全球气温上升在生物体、种群和生态系统层面产生了广泛影响。预计冬季气温升高将改变在此期间处于休眠状态的物种的能量代谢。刚孵化的彩龟（锦龟）在陆地上的浅巢中度过大约头8个月，在此期间，它们可能依靠剩余的卵黄储备来满足这段不活动时期的能量需求，直到春天破壳而出。我们进行了一项实验室实验，以描述刚孵化的锦龟剩余卵黄量的变化，并通过实验测试温度对剩余卵黄、幼龟大小以及越冬冬眠期存活率的影响。我们通过模拟两种自然热状况（“低温”与“高温”处理）以及一种接近2100年预计的更温暖温度的状况（“未来”处理）来操控冬季巢穴温度。由于高温会增加新陈代谢，我们预测未来温度处理会使冬季结束时剩余的卵黄量减少，并降低幼龟的体重和存活率。越冬后的剩余卵黄量与越冬前没有差异，并且到次年春天，温度对剩余卵黄量或幼龟存活率没有影响。然而，经历未来温度的幼龟在冬季比其他处理组的幼龟体重减轻得更多。这些结果与之前的研究一致，表明剩余卵黄并不能满足幼龟冬季的能量需求。未来变暖温度对体重的影响可能会在春季出蛰和扩散期间对能量需求较高的活动产生负面影响。
