Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.
Institute of Zoology, Universität Hamburg, Hamburg, Germany.
J Exp Zool A Ecol Integr Physiol. 2022 Jun;337(5):477-490. doi: 10.1002/jez.2582. Epub 2022 Feb 28.
Phenotypic plasticity may allow ectotherms with complex life histories such as amphibians to cope with climate-driven changes in their environment. Plasticity in thermal tolerance (i.e., shifts of thermal limits via acclimation to higher temperatures) has been proposed as a mechanism to cope with warming and extreme thermal events. However, thermal tolerance and, hence, acclimation capacity, is known to vary with life stage. Using the common frog (Rana temporaria) as a model species, we measured the capacity to adjust lower (CT ) and upper (CT ) critical thermal limits at different acclimation temperatures. We calculated the acclimation response ratio as a metric to assess the stage-specific acclimation capacity at each of seven consecutive ontogenetic stages and tested whether acclimation capacity was influenced by body mass and/or age. We further examined how acclimation temperature, body mass, age, and ontogenetic stage influenced CT and CT . In the temperate population of R. temporaria that we studied, thermal tolerance and acclimation capacity were affected by the ontogenetic stage. However, acclimation capacity at both thermal limits was well below 100% at all life stages tested. The lowest and highest acclimation capacity in thermal limits was observed in young and late larvae, respectively. The relatively low acclimation capacity of young larvae highlights a clear risk of amphibian populations to ongoing climate change. Ignoring stage-specific differences in thermal physiology may drastically underestimate the climate vulnerability of species, which will hamper successful conservation actions.
表型可塑性可能使具有复杂生活史的变温动物（如两栖动物）能够应对环境中由气候变化引起的变化。热耐受能力的可塑性（即通过适应更高温度来改变热极限）被认为是应对变暖及极端热事件的一种机制。然而，热耐受能力，从而适应能力，已知会随生命阶段而变化。我们使用常见的青蛙（Rana temporaria）作为模式物种，测量了在不同适应温度下调节较低（CT ）和较高（CT ）临界热极限的能力。我们计算了适应反应比，作为评估七个连续个体发育阶段中每个阶段的特定适应能力的指标，并检验了适应能力是否受到体重和/或年龄的影响。我们进一步研究了适应温度、体重、年龄和个体发育阶段如何影响 CT 和 CT 。在我们研究的 R. temporaria 温带种群中，热耐受性和适应能力受到个体发育阶段的影响。然而，在所有测试的生命阶段，两个热极限的适应能力都远低于 100%。在最年轻和最晚的幼虫中，分别观察到热极限的最低和最高适应能力。年轻幼虫的相对低适应能力突显了两栖动物种群对正在进行的气候变化的明显风险。忽略热生理的特定阶段差异可能会极大地低估物种的气候脆弱性，从而阻碍成功的保护行动。
