Data from: Thermal tolerance in the keystone species Daphnia magna –a candidate gene and an outlier analysis approach

Changes in temperature have occurred throughout Earth’s history. However, current warming trends exacerbated by human activities impose severe and rapid loss of biodiversity. Although understanding the mechanisms orchestrating organismal response to climate change is important, remarkably few studies document their role in nature. This is because only few systems enable the combined analysis of genetic and plastic responses to environmental change over long time-spans. Here, we characterize genetic and plastic responses to temperature increase in the aquatic keystone grazer Daphnia magna combining a candidate gene and an outlier analysis approach. We capitalize on the short generation time of our species, facilitating experimental evolution, and the production of dormant eggs enabling the analysis of long term response to environmental change through a resurrection ecology approach. We quantify plasticity in the expression of 35 candidate genes in D. magna populations resurrected from a lake that experienced changes in average temperature over the past century and from experimental populations differing in thermal tolerance isolated from a selection experiment. By measuring expression in multiple genotypes from each of these populations in control and heat treatments we assess plastic responses to extreme temperature events. By measuring evolutionary changes in gene expression between warm and cold adapted populations we assess evolutionary response to temperature changes. Evolutionary response to temperature increase is also assessed via an outlier analysis using EST-linked microsatellite loci. This study provides the first insights into the role of plasticity and genetic adaptation in orchestrating adaptive responses to environmental change in D. magna.地球演化历史中曾多次出现温度波动。然而，当前由人类活动加剧的全球变暖趋势，正造成严重且快速的生物多样性丧失。尽管解析生物应对气候变化的调控机制具有重要学术价值，但鲜有研究能够阐明这些机制在自然生态系统中的实际作用。这是因为极少有研究体系能够在长时间跨度内，同时分析生物对环境变化的遗传响应与表型可塑性响应（plastic response）。本研究结合候选基因分析与异常位点分析方法，对水生关键牧食物种大型溞（Daphnia magna）应对温度升高的遗传响应与表型可塑性响应进行了系统表征。我们利用该物种世代周期较短的特性开展实验进化研究，并借助其可产生休眠卵的特点，通过复活生态学（resurrection ecology）方法实现对环境变化的长期响应分析。我们对两类大型溞种群的35个候选基因的表达可塑性进行了定量分析：一类是从过去一个世纪平均温度发生变化的湖泊中复活得到的自然种群，另一类是从经过选择实验分离得到的、具有不同耐热性的实验种群。通过在对照与高温处理条件下，对每个种群的多个基因型的基因表达水平进行检测，我们评估了种群应对极端温度事件的表型可塑性响应。通过比较温适应与冷适应种群间的基因表达进化差异，我们解析了种群对温度变化的进化响应。此外，我们还利用与表达序列标签（Expressed Sequence Tag）关联的微卫星位点（microsatellite loci），通过异常位点分析方法，评估了种群对温度升高的进化响应。本研究首次揭示了表型可塑性与遗传适应在调控大型溞应对环境变化的适应性响应中所发挥的关键作用。