Evolve and Resquence (E&R) studies are a useful tool to study genomic processes during rapid adaptation, e.g., in the framework of adaptive responses to global climate change. We applied different thermal regimes to a natural Chironomus riparius (Diptera) population in an E&R framework to infer its evolutionary potential for rapid thermal adaptation. We exposed two replicates to three temperatures each (14°C, 20°C and 26°C) for more than two years, the experiment thus lasting 22, 44 or 65 generations, respectively. The two higher temperatures presented a priori moderate, respectively strong selection pressures. Life-cycle fitness tests revealed no appreciable adaptation to thermal regimes but a common adaptation of all six replicates probably due to the rearing conditions, presumably increased larval density and water quality. Genomic analyses showed a strong, genome-wide selective response in all replicates (mean s of selected SNPs = 0.305). This genomic response was significantly similar at all genomic levels among all replicates (SNPs, 10 kb windows, genes, exons, regions of elevated allele frequency change [REA]). The intersections among the replicates exposed to the same temperature were either insignificant or underrepresented. This confirmed a selective response to identical selection pressure(s), however, not to thermal regime. Genes closest to the SNP with the highest selection coefficient per REA were enriched for GO terms related to ion transport, regulation of transcription and signal transduction, which supported the presumed acting selection pressures. Our study showed the evolutionary potential for rapid adaptation by genome-wide and probably polygenic selection on standing genetic variation in C. riparius. However, because of the impossibility to accurately predict the acting selective regime in evolutionary experiments, we discuss the sobering perspectives for inferring the evolutionary potential of natural populations with this approach.

中文翻译：

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基因组过程的基础是自然Chiripomus riparius种群快速适应了意外施加的实验选择压力。

进化与响应（E＆R）研究是研究快速适应过程中基因组过程的有用工具，例如，在对全球气候变化的适应性响应框架内。我们在E＆R框架中对自然Chiripomus riparius（Diptera）种群应用了不同的热机制，以推断其快速热适应的进化潜力。我们将两个复制品分别暴露于三种温度（14°C，20°C和26°C）下超过两年，因此该实验分别持续了22、44或65代。较高的两个温度先验地表现出适度的，较强的选择压力。生命周期适应性测试表明，对热状况没有明显的适应性，但所有六个重复实验的共同适应性可能是由于饲养条件，推测为幼体密度和水质增加所致。基因组分析显示，所有重复样本均具有很强的全基因组选择性响应（所选SNP的平均值= 0.305）。在所有重复样本（SNP，10 kb窗口，基因，外显子，等位基因频率升高的区域[REA]）中，该基因组反应在所有基因组水平上都非常相似。暴露在相同温度下的复制品之间的交点不明显或代表性不足。这证实了对相同选择压力的选择性响应，但是对热态没有响应。每个REA中最接近SNP且具有最高选择系数的基因被丰富了有关离子运输，转录调控和信号转导的GO术语，从而支持了假定的作用选择压力。我们的研究表明，通过全基因组快速适应的进化潜力，以及可能对河豚曲霉的常规遗传变异进行多基因选择。但是，由于不可能在进化实验中准确预测作用选择机制，因此我们讨论了用这种方法推断自然种群进化潜力的清醒观点。