Strowbridge Nicholas, Gilbert Matthew J H, Zhang Yangfan, Metzger David C H, McKenzie Jessica L, Lima Lais, Farrell Anthony P, Fangue Nann A, Schulte Patricia M
Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada.
Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall Vancouver, BC V6T 1Z4, Canada.
Conserv Physiol. 2025 May 28;13(1):coaf034. doi: 10.1093/conphys/coaf034. eCollection 2025.
Phenotypic plasticity is thought to be critical in allowing organisms to cope with environmental change, but the factors that limit this plasticity are poorly understood, which hampers predictions of species resilience to anthropogenic climate change. Here, we ask if limited plasticity in key traits constrains performance at high temperatures, using two California hatchery strains of rainbow trout (). Aerobic and anaerobic metabolic performance declined at a high but ecologically relevant acclimation temperature (24°C), suggesting performance cannot be maintained at this temperature, despite acclimation. Similarly, while both whole-organism thermal tolerance and hypoxia tolerance improved with acclimation to moderately elevated temperatures, compensation was limited at the highest acclimation temperature. These limits at the whole-organism level were aligned with limits at lower levels of biological organization. At the organ level, absolute scope to increase heart rate with acute warming (Δƒ) did not increase between the upper two acclimation temperatures, and the safety margin for cardiac performance decreased at the highest acclimation temperature. At the cellular level, at 24°C, there were transcriptomic changes in the heart consistent with a cellular stress response. These limits across multiple levels of biological organization were observed under conditions that are ecologically relevant at the southern end of the species range, which suggests that thermal plasticity is likely insufficient to buffer rainbow trout against even modest anthropogenic warming in these regions.
表型可塑性被认为对于生物体应对环境变化至关重要，但限制这种可塑性的因素却知之甚少，这妨碍了对物种抵御人为气候变化能力的预测。在此，我们利用两种加利福尼亚孵化场养殖的虹鳟鱼品系，探究关键性状的有限可塑性是否会限制高温下的表现。在较高但生态相关的驯化温度（24°C）下，有氧和无氧代谢表现均下降，这表明尽管经过驯化，在此温度下仍无法维持表现。同样，虽然随着对适度升高温度的驯化，整体生物的热耐受性和缺氧耐受性均有所提高，但在最高驯化温度下补偿作用有限。整体生物水平的这些限制与较低生物组织水平的限制是一致的。在器官水平，随着急性升温增加心率的绝对范围（Δƒ）在上两个驯化温度之间并未增加，并且在最高驯化温度下心脏功能的安全边际降低。在细胞水平，在24°C时，心脏存在与细胞应激反应一致的转录组变化。在该物种分布范围南端生态相关的条件下观察到了跨多个生物组织水平的这些限制，这表明热可塑性可能不足以缓冲这些地区的虹鳟鱼抵御哪怕是适度的人为变暖。
