Adaptive evolution from standing genetic variation and physiological plasticity will fuel resilience in the geologically unprecedented warming and acidification of the earth's oceans. For marine animals, however, we have much to learn about the mechanisms, interactions, and costs of adaptation. Here, using 20 generations of experimental evolution followed by three generations of reciprocal transplantation, we investigate the relationship between adaptation and plasticity in the marine copepod, Acartia tonsa, in future greenhouse conditions (high temperature, high CO2). We find highly parallel genetic adaptation to greenhouse conditions in genes related to stress response, gene expression regulation, actin regulation, developmental processes, and energy production. However, reciprocal transplantation showed that genetic adaptation resulted in a loss of transcriptional plasticity, reduced fecundity, and reduced population growth when greenhouse animals were returned to ambient conditions or reared in low food conditions, suggestive of genetic assimilation after 20 generations of adaptation. Despite the loss of plasticity at F21, after three successive transplant generations, greenhouse-adapted animals were able to match the ambient-adaptive transcriptional profile. Concurrent changes in allele frequencies and erosion of nucleotide diversity suggest that this recovery occurred via adaptation back to ancestral conditions. These results demonstrate the power of experimental evolution from natural populations to reveal the mechanisms, timescales of responses, consequences, and reversibility of complex, physiological adaptation. While plasticity facilitated initial survival in global change conditions, it eroded after 20 generations as populations genetically adapted, limiting resilience to new stressors and previously benign environments.

中文翻译：

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长期适应海洋co足类动物的全球变化条件后，转录可塑性的丧失和恢复

来自常设遗传变异和生理可塑性的适应性进化将增强地球海洋前所未有的地质变暖和酸化的复原力。但是，对于海洋动物，我们有很多要学习的机制，相互作用和适应成本。在这里，使用20代的实验进化方法，再进行3代的相互移植，我们研究了未来温室条件（高温，高CO2）下海洋co足类动物（Acartiatonsa）的适应性与可塑性之间的关系。我们在与胁迫反应，基因表达调控，肌动蛋白调控，发育过程和能量产生有关的基因中发现了高度平行的遗传适应温室条件的基因。然而，相互移植表明，当温室动物恢复到环境条件或在低食物条件下饲养时，遗传适应会导致转录可塑性的丧失，繁殖力降低和种群增长减少，这表明适应20代后的遗传同化。尽管在F21上失去了可塑性，但在连续三代移植后，适应温室的动物仍能够匹配环境适应性转录谱。等位基因频率的同时变化和核苷酸多样性的侵蚀表明，这种恢复是通过适应祖先条件而发生的。这些结果证明了从自然种群进行实验演化的能力，揭示了复杂机制，响应的时间尺度，后果和可逆性，生理适应。尽管可塑性促进了全球变化条件下的最初生存，但随着人口的遗传适应，这种可塑性在20代后受到侵蚀，从而将适应力限制在新的压力源和先前良性的环境中。