Data from: Fluctuating temperature leads to evolution of thermal generalism and preadaptation to novel environments

Environmental fluctuations can select for generalism, which is also hypothesized to increase organisms’ ability to invade novel environments. Here, we show that across a range of temperatures, opportunistic bacterial pathogen Serratia marcescens that evolved in fluctuating temperature (daily variation between 24°C and 38°C, mean 31°C) outperforms the strains that evolved in constant temperature (31°C). The growth advantage was also evident in novel environments in the presence of parasitic viruses and predatory protozoans, but less clear in the presence of stressful chemicals. Adaptation to fluctuating temperature also led to reduced virulence in Drosophila melanogaster host, which suggests that generalism can still be costly in terms of reduced fitness in other ecological contexts. While supporting the hypothesis that evolution of generalism is coupled with tolerance to several novel environments, our results also suggest that thermal fluctuations driven by the climate change could affect both species’ invasiveness and virulence.环境波动可对泛化适应性（generalism）施加选择压力，且已有假说提出，泛化适应性可增强生物体入侵新生境的能力。本研究显示，在一系列温度条件下，于波动温度（每日温度在24℃至38℃间波动，平均温度31℃）环境中演化而来的机会致病细菌粘质沙雷氏菌（Serratia marcescens），其生长表现优于在恒定温度（31℃）环境中演化的菌株。该生长优势在存在寄生性病毒与掠食性原生动物的新生境中同样显著，但在存在胁迫性化学物质的环境中则不甚明确。对波动温度的适应性还会导致其在黑腹果蝇（Drosophila melanogaster）宿主中的毒力下降，这表明泛化适应性在其他生态背景下仍可能因适合度降低而付出演化代价。本研究结果既支持“泛化适应性的演化与对多种新生境的耐受性相关联”这一假说，同时也表明气候变化驱动的温度波动，可能会同时影响物种的入侵能力与毒力。