Plasticity and evolution are two processes allowing populations to respond to environmental changes, but how both are related and impact each other remains controversial. We studied plastic and evolutionary responses in gene expression of Tribolium castaneum after exposure of the beetles to new environments that differed from ancestral conditions in temperature, humidity or both. Using experimental evolution with 10 replicated lines per condition, we were able to demonstrate adaptation after 20 generations. We measured whole‐transcriptome gene expression with RNA‐sequencing to infer evolutionary and plastic changes. We found more evidence for changes in mean expression (shift in the intercept of reaction norms) in adapted lines than for changes in plasticity (shifts in slopes). Plasticity was mainly preserved in selected lines and was responsible for a large part of the phenotypic divergence in expression between ancestral and new conditions. However, we found that genes with the largest evolutionary changes in expression also evolved reduced plasticity and often showed expression levels closer to the ancestral stage. Results obtained in the three different conditions were similar, suggesting that restoration of ancestral expression levels during adaptation is a general evolutionary pattern. With a larger sample in the most stressful condition, we were able to detect a positive correlation between the proportion of genes with reversion of the ancestral plastic response and mean fitness per selection line.

中文翻译：

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恢复祖先表型是Tribolium castaneum在适应新环境期间基因表达进化的一般模式。

可塑性和进化是使人们能够对环境变化做出反应的两个过程，但是两者如何相互关联和相互影响仍存在争议。我们研究了蓖麻Tribolium castaneum基因表达中的可塑性和进化反应将甲虫暴露于温度，湿度或两者均不同于祖传条件的新环境后。使用每个条件下10条重复品系的实验进化，我们能够证明20代后的适应性。我们用RNA测序测量了整个转录组的基因表达，以推断进化和塑性变化。我们发现更多的证据表明适应线的平均表达发生变化（反应规范的截距发生变化），而不是塑性发生变化（斜率发生变化）。可塑性主要保留在选定的品系中，并且是祖先和新条件之间表达的大部分表型差异的原因。然而，我们发现表达中进化变化最大的基因也进化出可塑性降低，并且常常显示出更接近祖先阶段的表达水平。在三种不同条件下获得的结果相似，表明适应过程中祖先表达水平的恢复是一般的进化模式。在压力最大的情况下，使用更大的样本，我们能够检测到祖先塑性反应回复的基因比例与每个选择线的平均适应度之间呈正相关。