Loeschcke Volker, Hoffmann Ary A
Center of Environmental Stress Research, Department of Ecology and Genetics, University of Aarhus, Ny Munkegade, Building 1540, DK-8000 Aarhus C, Denmark.
Am Nat. 2007 Feb;169(2):175-83. doi: 10.1086/510632. Epub 2007 Jan 2.
Heat hardening increases thermal resistance to more extreme temperatures in the laboratory. However, heat hardening also has negative consequences, and the net benefit of hardening has not been evaluated in the field. We tested short-term heat hardening effects on the likelihood of Drosophila melanogaster to be caught at different temperatures at baits in field sites without natural resources. We predicted that hardened flies should be more frequently caught at the baits at high but not low temperatures. Under cool conditions, flies hardened at 36 degrees C, and to a lesser extent at 34 degrees C, were less frequently caught at baits than nonhardened flies a few hours after release, indicating a negative effect of hardening. In later captures, negative effects tended to disappear, particularly in males. Under warm conditions, there was an overall balance of negative and positive effects, though with a different temporal resolution. Under very hot conditions, when capture rates were low, there was a large benefit of hardening at 36 degrees C and 34 degrees C but not 33 degrees C. Finally, based on climatic records, the overall benefit of hardening in D. melanogaster is discussed as an evolved response to high temperatures occasionally experienced by organisms at some locations.
在实验室中，热硬化可增强对更极端温度的热耐受性。然而，热硬化也有负面影响，且在野外环境中硬化的净效益尚未得到评估。我们测试了短期热硬化对黑腹果蝇在没有自然资源的野外地点不同温度下在诱饵处被捕获可能性的影响。我们预测，经过硬化处理的果蝇在高温而非低温下应更频繁地在诱饵处被捕获。在凉爽条件下，在36摄氏度硬化的果蝇，以及在较小程度上在34摄氏度硬化的果蝇，在释放后几小时内，在诱饵处被捕获的频率低于未硬化的果蝇，这表明硬化存在负面影响。在后续的捕获中，负面影响往往会消失，尤其是在雄性果蝇中。在温暖条件下，虽然时间分辨率不同，但总体上正负效应相互平衡。在非常炎热的条件下，当捕获率较低时，在36摄氏度和34摄氏度而非33摄氏度下进行硬化处理有很大益处。最后，基于气候记录，讨论了黑腹果蝇硬化的总体益处，将其作为生物体在某些地点偶尔经历的高温的一种进化反应。
