The adaptive value of phenotypic plasticity for performance under single stressors is well documented. However, plasticity may only truly be adaptive in the natural multifactorial environment if it confers resilience to stressors of a different nature, a phenomenon known as cross‐tolerance. An understanding of the mechanistic basis of cross‐tolerance is essential to aid prediction of species resilience to future environmental change. Here, we identified mechanisms underpinning cross‐tolerance between two stressors predicted to increasingly challenge aquatic ecosystems under climate change, chronic warming and hypoxia, in an ecologically‐important aquatic invertebrate. Warm acclimation improved hypoxic performance through an adaptive hypometabolic strategy and changes in the expression of hundreds of genes that are important in the response to hypoxia. These ‘frontloaded’ genes showed a reduced reaction to hypoxia in the warm acclimated compared to the cold acclimated group. Frontloaded genes included stress indicators, immune response and protein synthesis genes that are protective at the cellular level. We conclude that increased constitutive gene expression as a result of warm acclimation reduced the requirement for inducible stress responses to hypoxia. We propose that transcriptional frontloading contributes to cross‐tolerance between stressors and may promote fitness of organisms in environments increasingly challenged by multiple anthropogenic threats.

中文翻译：

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转录前载有助于应激源之间的交叉耐受


表型可塑性对单一应激源下表现的适应性价值已有充分记录。然而，只有当可塑性赋予不同性质的压力源弹性时，它才可能真正适应自然多因素环境，这种现象称为交叉耐受。了解交叉耐受的机制基础对于帮助预测物种对未来环境变化的适应能力至关重要。在这里，我们确定了两种压力源之间交叉耐受性的机制，这些压力源预计将在气候变化、长期变暖和缺氧的情况下对生态重要的水生无脊椎动物日益挑战水生生态系统。温暖的驯化通过适应性低代谢策略和数百个对缺氧反应很重要的基因表达的变化来改善缺氧表现。与冷适应组相比，这些“前装”基因在热适应组中表现出对缺氧的反应减少。前置基因包括应激指标、免疫反应和在细胞水平上具有保护作用的蛋白质合成基因。我们得出的结论是，温暖驯化导致的组成型基因表达增加减少了对缺氧诱导应激反应的需要。我们认为转录前载有助于应激源之间的交叉耐受，并可能促进生物体在日益受到多种人为威胁挑战的环境中的适应性。