Data from: Fitness costs of rapid cold-hardening in Ceratitis capitata

Rapid cold-hardening (RCH) is a unique form of phenotypic plasticity which confers survival advantages at low temperature. The fitness costs of RCH are generally poorly elucidated and are important to understanding the evolution of plastic physiology. This study examined whether RCH responses, induced by ecologically relevant diel temperature fluctuations, carry metabolic, survival or fecundity costs. We predicted that potential costs in RCH would be manifested as differences in metabolic rate, fecundity or survival in flies which have hardened versus those which have not, or flies which have experienced more RCH events would show greater costs than those which have experienced fewer events. One group of flies cooled to 10°C for 2h for 11 consecutive days experienced daily RCH (Hardened), whilst the other group exposed to 15°C for the same 2h period each day formed a Control group. Hardened flies had higher survival at -5°C for 2h than control flies (69±9% vs. 44±19%, P=0.04). Hardened flies showed no metabolic or fecundity costs, but had reduced average survival (P=0.0403). Thus, a major cost to repeated low temperature exposures in C. capitata is through direct mortality caused by chilling injury, although this appears not to be a direct cost of RCH.快速冷驯化（Rapid cold-hardening, RCH）是一种独特的表型可塑性形式，能够赋予生物在低温环境下的生存优势。目前关于RCH的适合度成本仍鲜有阐释，而这对于理解可塑性生理的演化过程至关重要。本研究探讨了由生态相关的昼夜温度波动诱导的RCH响应是否会带来代谢、生存或繁殖力方面的成本。我们预测，RCH的潜在成本将表现为已发生冷驯化的果蝇与未发生冷驯化的果蝇在代谢率、繁殖力或存活率上的差异，或是经历更多次RCH事件的果蝇相较于经历较少事件的个体将表现出更显著的成本。一组果蝇连续11天每日于10℃条件下冷却2小时，每日完成RCH驯化（以下称驯化组），另一组每日于相同时长的15℃条件下处理的果蝇则作为对照组。驯化组果蝇在-5℃下处理2小时的存活率显著高于对照组（69±9% vs. 44±19%，P=0.04）。驯化组果蝇未表现出代谢或繁殖力层面的成本，但平均存活率有所降低（P=0.0403）。由此可见，地中海实蝇（C. capitata）反复暴露于低温环境的主要成本源于冷损伤引发的直接死亡，尽管这似乎并非RCH本身的直接成本。