冬季寒冷会减缓外温学,潜在的限制活动和生态机会在极地纬度。然而,许多鱼类冬季活跃,通过热补偿促进,提高冷性能。相反,冬季休眠鱼类(例如,cunner,Tatogolabrusadspersus)变得不活跃且不进食过冬。为什么某些鱼类冬季休眠?我们假设冬季休眠是一种适应性行为反应,冷对其生理表现的无补偿约束。我们预测,在7-8°C的休眠阈值以下,cunner的运动和代谢表现大大降低,即使在适应之后(即,显示高于正常值,未补偿的热灵敏度,Q10>1-3)。我们测量了多个关键性能指标(例如,C-启动最大速度,追逐游泳速度,有氧范围)在急性暴露于26-2°C(使用14°C适应鱼的3°C间隔)或适应(5-8周)至14-2°C(3°C间隔包围休眠阈值)后的cunner。性能随降温而下降,所有六个性能率指标的急性Q10在休眠阈值温度(Q10(8-2°C)急性=1.5-4.9,平均值=3.3)以下显着大于(Q10(14-8°C)急性=1.1-1.9,平均值=1.5),推断一个冷约束。然而,2°C的适应(暂时与季节性冷却更相关)改善了性能,消除急性约束(Q10(8-2°C)适应=1.4-3.0,平均值=2.0;也c.f.Q10(14-8°C)适应=1.2-2.9,平均值=1.7)。因此,休眠的cunner表现出运动和代谢表现的部分冷补偿,类似于冬季活跃物种。对C-start刺激的反应,然而,即使在适应环境后,也受到了极大的冷约束,提示休眠涉及感觉限制。代谢和运动生理的热约束并不是cunner冬季休眠的重要驱动因素。事实上,即使在休眠的鱼中,在寒冷的温度下也能保持补偿性可塑性。
Winter cold slows ectotherm physiology, potentially constraining activities and ecological opportunities at poleward latitudes. Yet, many fishes are winter-active, facilitated by thermal compensation that improves cold performance. Conversely, winter-dormant fishes (e.g. cunner, Tautogolabrus adspersus) become inactive and non-feeding overwinter. Why are certain fishes winter-dormant? We hypothesized that winter dormancy is an adaptive behavioural response arising in poleward species that tolerate severe, uncompensated constraints of cold on their physiological performance. We predicted that below their dormancy threshold of 7--8°C, exercise and metabolic performance of cunner are greatly decreased, even after acclimation (i.e. shows above-normal, uncompensated thermal sensitivity, Q10>1-3). We measured multiple key performance metrics (e.g. C-start maximum velocity, chase swimming speed, aerobic scope) in cunner after acute exposure to 26-2°C (3°C intervals using 14°C-acclimated fish) or acclimation (5-8 weeks) to 14-2°C (3°C intervals bracketing the dormancy threshold). Performance declined with cooling, and the acute Q10 of all six performance rate metrics was significantly greater below the dormancy threshold temperature (Q10,acute8-2°C=1.5-4.9, mean=3.3) than above (Q10,acute14-8°C=1.1-1.9, mean=1.5), inferring a cold constraint. However, 2°C acclimation (temporally more relevant to seasonal cooling) improved performance, abolishing the acute constraint (Q10,acclimated8-2°C=1.4-3.0, mean=2.0; also cf. Q10,acclimated14-8°C=1.2-2.9, mean=1.7). Thus, dormant cunner show partial cold-compensation of exercise and metabolic performance, similar to winter-active species. However, responsiveness to C-start stimuli was greatly cold-constrained even following acclimation, suggesting dormancy involves sensory limitation. Thermal constraints on metabolic and exercise physiology are not significant drivers of winter dormancy in cunner. In fact, compensatory plasticity at frigid temperatures is retained even in a dormant fish.