Although high CO₂ and warming could act interactively on marine phytoplankton, little is known about the molecular basis for this interaction on an evolutionary scale. Here we explored the adaptation to high CO₂ in combination with warming in a model marine diatom Phaeodactylum tricornutum. Whole-genome re-sequencing identifies, in comparison to populations grown under control conditions, a larger genetic diversity loss and a higher genetic differentiation in the populations adapted for 2 years to warming than in those adapted to high CO₂. However, this diversity loss was less under high CO₂ combined with warming, suggesting that the evolution driven by warming was constrained by high CO₂. By integrating genomics, transcriptomics, and physiological data, we found that the underlying molecular basis for this constraint is associated with the expression of genes involved in some key metabolic pathways or biological processes, such as the glyoxylate pathway, amino acid and fatty acid metabolism, and diel variability. Our results shed new light on the evolutionary responses of marine phytoplankton to multiple environmental changes in the context of global change and provide new insights into the molecular basis underpinning interactions among those multiple drivers.

尽管高 CO ₂和变暖可以相互作用影响海洋浮游植物，但对于这种相互作用在进化尺度上的分子基础知之甚少。在这里，我们探索了模型海洋硅藻Phaeodactylum tricornutum对高 CO ₂结合变暖的适应。_{与在控制条件下生长的种群相比，全基因组重测序发现，与适应高 CO 2}的种群相比，适应变暖 2 年的种群遗传多样性损失更大，遗传分化更高。然而，这种多样性损失在高 CO ₂和变暖的情况下较小，表明变暖驱动的进化受到高 CO _2的限制. 通过整合基因组学、转录组学和生理学数据，我们发现这种限制的潜在分子基础与参与某些关键代谢途径或生物过程的基因表达有关，例如乙醛酸途径、氨基酸和脂肪酸代谢，和昼夜变异性。我们的研究结果揭示了海洋浮游植物在全球变化背景下对多种环境变化的进化反应，并为支持这些多种驱动因素之间相互作用的分子基础提供了新的见解。