Validity of Thermal Ramping Assays Used to Assess Thermal Tolerance in Arthropods
Validity of Thermal Ramping Assays Used to Assess Thermal Tolerance in Arthropods
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DOI：
10.1371/journal.pone.0032758
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发表时间：
2012-03-09
期刊：
影响因子：
3.7
通讯作者：
Sorensen, Jesper Givskov
中科院分区：
文献类型：
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作者：
Overgaard, Johannes;Kristensen, Torsten Nygaard;Sorensen, Jesper Givskov
正确评估动物的环境抵抗力对于研究人员了解环境条件的变化如何影响种群和物种丰度的能力至关重要。昆虫的温度上限研究也是如此，在实验室条件下研究动物的研究人员必须选择适当的方法得出结论。理想情况下，这些方法应该精确地估计感兴趣的性状，并且也具有生物学意义。在开发这种测试的尝试中，已经提出热斜坡测定法是用于小昆虫的有用测定法，因为它们结合了生态学相关的逐渐温度变化。然而，最近基于模型的论文表明，热阻的估计可能会受到同时饥饿和脱水胁迫的强烈干扰。在本研究中，我们使用两组独立实验对这些模型预测进行了实证测试。我们清楚地表明，从斜坡测定的小昆虫（果蝇）的结果不受饥饿或脱水压力。首先，我们指出，水平衡和能量平衡的轻微扰动，D。在斜升试验期间经历的黑腹果蝇的热耐受性不会混淆耐热性估计。其次，我们表明，苍蝇预先暴露于饥饿和脱水有“正常”的耐热性和热应激的抵抗力是独立的苍蝇的能量和水的状态。在我们的研究结果的基础上，我们讨论了在最近的模型论文中使用的假设，并提出了论点，为什么斜坡试验是一个有效的和生态相关的方式来测量昆虫的热阻。
Proper assessment of environmental resistance of animals is critical for the ability of researchers to understand how variation in environmental conditions influence population and species abundance. This is also the case for studies of upper thermal limits in insects, where researchers studying animals under laboratory conditions must select appropriate methodology on which conclusions can be drawn. Ideally these methods should precisely estimate the trait of interest and also be biological meaningful. In an attempt to develop such tests it has been proposed that thermal ramping assays are useful assays for small insects because they incorporate an ecologically relevant gradual temperature change. However, recent model-based papers have suggested that estimates of thermal resistance may be strongly confounded by simultaneous starvation and dehydration stress. In the present study we empirically test these model predictions using two sets of independent experiments. We clearly demonstrate that results from ramping assays of small insects (Drosophila melanogaster) are not compromised by starvation-or dehydration-stress. Firstly we show that the mild disturbance of water and energy balance of D. melanogaster experienced during the ramping tests does not confound heat tolerance estimates. Secondly we show that flies pre-exposed to starvation and dehydration have "normal" heat tolerance and that resistance to heat stress is independent of the energetic and water status of the flies. On the basis of our results we discuss the assumptions used in recent model papers and present arguments as to why the ramping assay is both a valid and ecologically relevant way to measure thermal resistance in insects.