Data from: A Drosophila laboratory evolution experiment points to low evolutionary potential under increased temperatures likely to be experienced in the future

The ability to respond evolutionarily to increasing temperatures is important for survival of ectotherms in a changing climate. Recent studies suggest that upper thermal limits may be evolutionary constrained. We address this hypothesis in a laboratory evolution experiment, encompassing ecologically relevant thermal regimes. To examine the potential for species to respond to climate change, we exposed replicate populations of Drosophila melanogaster to increasing temperatures (0.3 °C every generation) for 20 generations, whereas corresponding replicate control populations were held at benign thermal conditions throughout the experiment. We hypothesized that replicate populations exposed to increasing temperatures would show increased resistance to warm and dry environments compared with replicate control populations. Contrasting replicate populations held at the two thermal regimes showed (i) an increase in desiccation resistance and a decline in heat knock-down resistance in replicate populations exposed to increasing temperatures, (ii) similar egg-to-adult viability and fecundity in replicate populations from the two thermal regimes, when assessed at high stressful temperatures and (iii) no difference in nucleotide diversity between thermal regimes. The limited scope for adaptive evolutionary responses shown in this study highlights the challenges faced by ectotherms under climate change.在气候变化背景下，外温动物（ectotherms）具备对温度升高产生适应性演化响应的能力，对其生存至关重要。近期研究显示，物种的高温耐受上限可能受到演化约束。我们通过一项涵盖生态相关热制度的实验室演化实验，对这一假说展开验证。为探究物种应对气候变化的演化潜力，我们将黑腹果蝇（Drosophila melanogaster）的重复种群置于每代升温0.3℃的环境中，持续处理20代；同时设置对应的重复对照种群，在整个实验周期内均维持在温和适宜的热条件下。我们提出如下假说：相较于对照种群，经历持续升温的重复种群对温热干燥环境的抗性将有所提升。对两种热制度下的重复种群进行对比分析后，我们发现：(i) 持续升温组的抗干燥能力有所提升，但高温击倒抗性（heat knock-down resistance）出现下降；(ii) 在高胁迫高温条件下开展评估时，两种热制度种群的卵至成虫存活率与繁殖力均无显著差异；(iii) 不同热制度种群的核苷酸多样性不存在显著差异。本研究观测到的适应性演化响应范围有限，这凸显了气候变化背景下外温动物所面临的生存挑战。