Pang Mengwen, Gao Zuyuan, Huang Lingfeng, Chan Chuk Man, Zhang Xiaodong, Su Ruilin, Pan Ke, Liu Hongbin
Shenzhen Key Laboratory of Marine Microbiome Engineering Institute for Advanced Study, Shenzhen University, Shenzhen, China.
College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.
Glob Chang Biol. 2025 Jun;31(6):e70280. doi: 10.1111/gcb.70280.
The rise in surface ocean temperature imposes strong effects on marine organisms. With large population sizes and fast generation times, microorganisms may rapidly adapt to ocean warming. However, long-term experimental adaptation studies on heterotrophic protists are very limited, hindering our comprehensive understanding of their adaptation capability and the underlying mechanisms. In this study, we conducted long-term thermal selection experiments on six representative marine protozoa. By assessing their phenotypes, metabolism, thermal performance curves, thermal traits, and carbon allocation status, we found that all investigated heterotrophic protists exhibited a fitness-improved adaptation response to warming scenarios. After growing in warmer conditions for hundreds of generations (~850 for Cafeteria burkhardae and ~500 for other species), their optimal temperature and maximum rates of both growth and ingestion increased, whereas respiration rates significantly decreased. In addition, the cell size, cellular carbon, and nitrogen content at an elevated environmental temperature also increased after warming adaptation. Mechanisms underlying the increased competitive fitness at high temperatures after warming adaptation might be associated with the alleviated oxidative stress, shown by the remarkable reduction in cellular reactive oxygen species contents. Our study, for the first time, reveals the ability of marine heterotrophic protists to adapt to higher temperatures, providing experimental support for predictive modeling studies that integrate evolutionary potential with short-term physiological responses, with important implications for marine ecosystem functioning and biogeochemical cycling under global warming.
海洋表层温度的上升对海洋生物产生了强烈影响。微生物数量众多且世代时间短，可能会迅速适应海洋变暖。然而，关于异养原生生物的长期实验适应性研究非常有限，这阻碍了我们对其适应能力及其潜在机制的全面理解。在本研究中，我们对六种具有代表性的海洋原生动物进行了长期热选择实验。通过评估它们的表型、代谢、热性能曲线、热特性和碳分配状态，我们发现所有被研究的异养原生生物在变暖情景下都表现出适应性反应，适应能力有所提高。在较温暖的条件下生长数百代后（伯克哈德卡氏长吸管虫约850代，其他物种约500代），它们的最适温度以及生长和摄食的最大速率都增加了，而呼吸速率则显著下降。此外，变暖适应后，在升高的环境温度下细胞大小、细胞碳和氮含量也增加了。变暖适应后高温下竞争适应性增加的潜在机制可能与氧化应激的减轻有关，细胞活性氧含量显著降低表明了这一点。我们的研究首次揭示了海洋异养原生生物适应更高温度的能力，为将进化潜力与短期生理反应相结合的预测模型研究提供了实验支持，对全球变暖下的海洋生态系统功能和生物地球化学循环具有重要意义。
