Data from: Strong costs and benefits of winter acclimatization in Drosophila melanogaster

Studies on thermal acclimation in insects are often performed on animals acclimated in the laboratory under conditions that are not ecologically relevant. Costs and benefits of acclimation responses under such conditions may not reflect costs and benefits in natural populations subjected to daily and seasonal temperature fluctuations. Here we estimated costs and benefits in thermal tolerance limits in relation to winter acclimatization of Drosophila melanogaster. We sampled flies from a natural habitat during winter in Denmark (field flies) and compared heat and cold tolerance of these to that of flies collected from the same natural population, but acclimated to 25 °C or 13 °C in the laboratory (laboratory flies). We further obtained thermal performance curves for egg-to-adult viability of field and laboratory (25 °C) flies, to estimate possible cross-generational effects of acclimation. We found much higher cold tolerance and a lowered heat tolerance in field flies compared to laboratory flies reared at 25 °C. Flies reared in the laboratory at 13 °C exhibited the same thermal cost-benefit relations as the winter acclimatized flies. We also found a cost of winter acclimatization in terms of decreased egg-to-adult viability at high temperatures of eggs laid by winter acclimatized flies. Based on our findings we suggest that winter acclimatization in nature can induce strong benefits in terms of increased cold tolerance. These benefits can be reproduced in the laboratory under ecologically relevant rearing and testing conditions, and should be incorporated in species distribution modelling. Winter acclimatization also leads to decreased heat tolerance. This may create a mismatch between acclimation responses and the thermal environment, e.g. if temperatures suddenly increase during spring, under current and expected more variable future climatic conditions.

关于昆虫热驯化（thermal acclimation）的研究，通常在不具备生态相关性的实验室条件下对昆虫进行驯化。此类条件下驯化反应的成本与收益，或无法反映经历每日与季节性温度波动的自然种群中的实际成本与收益。本研究以黑腹果蝇（Drosophila melanogaster）为研究对象，估算了与其冬季驯化适应（winter acclimatization）相关的热耐受极限（thermal tolerance limits）成本与收益。我们于丹麦冬季的自然栖息地采集果蝇（野外果蝇），并将其耐热与耐寒能力，与同一自然种群采集后在实验室分别驯化于25℃或13℃的果蝇（实验室果蝇）进行对比。我们还分别获取了野外果蝇与25℃驯化实验室果蝇的卵至成虫存活率（egg-to-adult viability）热性能曲线（thermal performance curves），以评估驯化可能存在的跨代效应（cross-generational effects）。结果显示，与在25℃下饲养的实验室果蝇相比，野外果蝇的耐寒能力显著提升，耐热能力则有所下降。在13℃实验室条件下饲养的果蝇，其热成本-收益关系与冬季驯化适应的果蝇完全一致。我们还发现冬季驯化适应存在一项成本：冬季驯化适应果蝇所产的卵，在高温环境下的卵至成虫存活率出现下降。基于本研究结果，我们提出：自然界中的冬季驯化适应可通过提升耐寒能力带来显著收益。此类收益可在具备生态相关性的饲养与测试条件下于实验室复现，且应被纳入物种分布模型（species distribution modelling）。冬季驯化适应同时会导致耐热能力下降。在当前及未来预期气候更趋多变的背景下，若春季温度突然升高，这种情况可能会造成驯化反应与热环境之间的错配。