• The prevalence of local adaptation and phenotypic plasticity among populations is critical to accurately predicting when and where climate change impacts will occur. Currently, comparisons of thermal performance between populations are untested for most marine species or overlooked by models predicting the thermal sensitivity of species to extirpation.
• Here we compared the ecological response and recovery of seagrass populations (Posidonia oceanica) to thermal stress throughout a year-long translocation experiment across a 2800-km gradient in ocean climate. Transplants in central and warm-edge locations experienced temperatures > 29°C, representing thermal anomalies > 5°C above long-term maxima for cool-edge populations, 1.5°C for central and < 1°C for warm-edge populations.
• Cool-edge, central and warm-edge populations differed in thermal performance when grown under common conditions, but patterns contrasted with expectations based on thermal geography. Cool-edge populations did not differ from warm-edge populations under common conditions and performed significantly better than central populations in growth and survival.
• Our findings reveal that thermal performance does not necessarily reflect the thermal geography of a species. We demonstrate that warm-edge populations can be less sensitive to thermal stress than cooler, central populations suggesting that Mediterranean seagrasses have greater resilience to warming than current paradigms suggest.

中文翻译：

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海草种群对热应激的恢复力并不反映海洋气候的区域差异

• 人群中局部适应和表型可塑性的普遍性对于准确预测气候变化影响何时何地发生至关重要。目前，对于大多数海洋物种来说，种群之间的热性能比较未经测试，或者被预测物种对灭绝的热敏感性的模型所忽视。
• 在这里，我们比较了海草种群 ( Posidonia oceanica )的生态响应和恢复对热应力的影响，该实验在长达一年的易位实验中跨越了 2800 公里的海洋气候梯度。中部和暖边地区的移植物温度> 29°C，代表冷边种群的热异常高于长期最大值> 5°C，中部和暖边种群为1.5°C，<1°C。
• 在普通条件下生长时，冷边、中央和暖边种群的热性能不同，但模式与基于热地理学的预期形成对比。在普通条件下，冷边种群与暖边种群没有区别，并且在生长和生存方面的表现明显优于中心种群。
• 我们的研究结果表明，热性能不一定反映一个物种的热地理。我们证明，与较冷的中央种群相比，暖边种群对热应力的敏感性较低，这表明地中海海草对变暖的抵抗力比目前的范式所暗示的要大。