Ectotherms can respond to climate change via evolutionary adaptation, usually resulting in an increase of their upper thermal tolerance. But whether such adaptation influences the phenotypic plasticity of thermal tolerance when encountering further environmental stressors is not clear yet. This is crucial to understand because organisms experience multiple stressors, besides warming climate, in their natural environment and pollution is one of those. Here, we studied the phenotypic plasticity of thermal tolerance in three-spined stickleback populations inhabiting spatially replicated thermally polluted and pristine areas before and after exposing them to a sublethal concentration of copper for one week. We found that the upper thermal tolerance and its phenotypic plasticity after copper exposure did not depend on the thermal history of fish, suggesting that five decades of thermal pollution did not result in evolutionary adaptation to thermal tolerance. The upper thermal tolerance of fish was, on the other hand, increased by ∼ 1.5 °C after 1-week copper exposure in a sex-specific manner, with males having higher plasticity. To our knowledge this is the first study that shows an improvement of the upper thermal tolerance as a result of metal exposure. The results suggest that three-spined sticklebacks are having high plasticity and they are capable of surviving in a multiple-stressor scenario in the wild and that male sticklebacks seem more resilient to fluctuating environmental conditions than female.

变温动物可以通过进化适应来应对气候变化，通常会导致它们的上限耐热性增加。但是，当遇到进一步的环境压力时，这种适应是否会影响耐热性的表型可塑性尚不清楚。理解这一点至关重要，因为除了气候变暖之外，生物体在其自然环境中还会经历多种压力源，而污染就是其中之一。在这里，我们研究了居住在空间复制的热污染和原始区域的三刺棘鱼种群在将它们暴露于亚致死浓度的铜一周之前和之后的耐热性的表型可塑性。我们发现铜暴露后的耐热性上限及其表型可塑性不取决于鱼类的热历史，表明五个十年的热污染并没有导致对耐热性的进化适应。另一方面，在铜暴露 1 周后，鱼的耐热性上限以性别特异性方式增加了约 1.5°C，雄性具有更高的可塑性。据我们所知，这是第一项显示由于金属暴露而提高耐热性上限的研究。结果表明，三刺棘鱼具有很高的可塑性，它们能够在野外的多重压力环境中生存，而且雄性棘鱼似乎比雌性更能适应波动的环境条件。1 周铜暴露后 5°C 以特定性别的方式进行，雄性具有更高的可塑性。据我们所知，这是第一项显示由于金属暴露而提高耐热性上限的研究。结果表明，三刺棘鱼具有很高的可塑性，它们能够在野外的多重压力环境中生存，而且雄性棘鱼似乎比雌性更能适应波动的环境条件。1 周铜暴露后 5°C 以特定性别的方式进行，雄性具有更高的可塑性。据我们所知，这是第一项显示由于金属暴露而提高耐热性上限的研究。结果表明，三刺棘鱼具有很高的可塑性，它们能够在野外的多重压力环境中生存，而且雄性棘鱼似乎比雌性更能适应波动的环境条件。