Genetic diversity within coastal foundation species can enhance species and ecosystem resilience to ocean warming and marine heatwaves. However, the effects of diversity on ecosystem function are often context-dependent and mechanisms underpinning, such contingency, remain poorly understood. To test the relationship between genetic diversity and resilience to warming in a coastal foundation species, we planted eelgrass (Zostera marina) pots at two levels of genotypic richness (1 genotype monocultures or 4 genotype mixtures) and exposed these pots to warming events of different frequencies (sustained or alternating) in mesocosms for four months (mid-summer to late fall). Our results revealed that in monocultures warming reduced pot biomass by 15.8% but warming led to overyielding in mixtures by 33.3%. In contrast, mixture biomass at control temperatures underyielded by 13.2%. Overyielding of mixtures during sustained warming was driven by positive complementarity, which appears to be the result of warming-induced shifts in the relative performance of genotypes over time. We propose that high temperature stress created a tradeoff, such that some genotypes experienced greater photoinhibiton during mid-summer while other genotypes were light limited during the late fall. Thus, seasonal differences in temperature and light conditions in the warming treatment generated asynchrony in genotype peak performance, freed genotypes from competitive interactions, and allowed overyielding via complementarity to occur. While we demonstrate that the effects of diversity on ecosystem function depend on environmental context as well as trait variation among genotypes, our results underscore that maintaining or restoring genetic diversity could dramatically improve the resilience of coastal foundation species to future ocean warming.

沿海基础物种内部的遗传多样性可以增强物种和生态系统对海洋变暖和海洋热浪的适应力。但是，多样性对生态系统功能的影响通常取决于具体情况，而这种偶然性的支撑机制仍然知之甚少。为了测试沿海基础物种的遗传多样性与抗逆能力之间的关系，我们种植了鳗el（Zostera marina））处于两个基因型丰富度水平的花盆（1个基因型单一培养物或4个基因型混合物），并使这些花盆在中胚层中暴露于不同频率（持续或交替）的变暖事件四个月（夏末至深秋）。我们的结果表明，在单培养中，变暖会使盆栽生物量减少15.8％，但变暖导致混合物的高产33.3％。相反，在控制温度下的混合生物质收率降低了13.2％。持续增温期间混合物的过度增产是由积极的互补性驱动的，这似乎是由于增温引起的基因型相对性能随时间变化的结果。我们提出高温胁迫产生了一个折衷，使得某些基因型在仲夏期间经历更大的光抑制作用，而其他基因型在秋季末期受到光限制。从而，暖化处理中温度和光照条件的季节性差异会导致基因型峰值表现出现异步，使基因型摆脱竞争性相互作用，并因互补而产生过量产量。尽管我们证明多样性对生态系统功能的影响取决于环境背景以及基因型之间的性状变异，但我们的结果强调，维持或恢复遗传多样性可以显着提高沿海基础物种对未来海洋变暖的适应力。