Stitt Bradley C, Burness Gary, Burgomaster Kirsten A, Currie Suzanne, McDermid Jenni L, Wilson Chris C
Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario K9J 7B8, Canada; 2Department of Biology, Trent University, Peterborough, Ontario K9J 7B8, Canada; 3Department of Biology, Mount Allison University, Sackville, New Brunswick E4L 1G7, Canada; 4Wildlife Conservation Society Canada, Trent University, Peterborough, Ontario K9J 7B8, Canada; 5Ontario Ministry of Natural Resources, Trent University, Peterborough, Ontario K9J 7B8, Canada.
Physiol Biochem Zool. 2014 Jan-Feb;87(1):15-29. doi: 10.1086/675259.
Cold-water fishes are becoming increasingly vulnerable as changing thermal conditions threaten their future sustainability. Thermal stress and habitat loss from increasing water temperatures are expected to impact population viability, particularly for inland populations with limited adaptive resources. Although the long-term persistence of cold-adapted species will depend on their ability to cope with and adapt to changing thermal conditions, very little is known about the scope and variation of thermal tolerance within and among conspecific populations and evolutionary lineages. We studied the upper thermal tolerance and capacity for acclimation in three captive populations of brook trout (Salvelinus fontinalis) from different ancestral thermal environments. Populations differed in their upper thermal tolerance and capacity for acclimation, consistent with their ancestry: the northernmost strain (Lake Nipigon) had the lowest thermal tolerance, while the strain with the most southern ancestry (Hill's Lake) had the highest thermal tolerance. Standard metabolic rate increased following acclimation to warm temperatures, but the response to acclimation varied among strains, suggesting that climatic warming may have differential effects across populations. Swimming performance varied among strains and among acclimation temperatures, but strains responded in a similar way to temperature acclimation. To explore potential physiological mechanisms underlying intraspecific differences in thermal tolerance, we quantified inducible and constitutive heat shock proteins (HSP70 and HSC70, respectively). HSPs were associated with variation in thermal tolerance among strains and acclimation temperatures; HSP70 in cardiac and white muscle tissues exhibited similar patterns, whereas expression in hepatic tissue varied among acclimation temperatures but not strains. Taken together, these results suggest that populations of brook trout will vary in their ability to cope with a changing climate.
随着热条件的变化威胁到冷水鱼类未来的可持续性，它们正变得越来越脆弱。水温升高导致的热应激和栖息地丧失预计将影响种群的生存能力，对于适应性资源有限的内陆种群尤其如此。尽管适应寒冷物种的长期存续将取决于它们应对和适应不断变化的热条件的能力，但对于同种种群和进化谱系内部和之间的热耐受性范围和变化却知之甚少。我们研究了来自不同原始热环境的三个养殖溪红点鲑（Salvelinus fontinalis）种群的热耐受性上限和适应能力。种群在热耐受性上限和适应能力方面存在差异，这与它们的祖先情况一致：最北部的品系（尼皮贡湖）热耐受性最低，而具有最南部祖先的品系（希尔湖）热耐受性最高。适应温暖温度后，标准代谢率增加，但各品系对适应的反应有所不同，这表明气候变暖可能对不同种群产生不同影响。游泳表现因品系和适应温度而异，但品系对温度适应的反应方式相似。为了探究热耐受性种内差异潜在的生理机制，我们分别量化了诱导型和组成型热休克蛋白（分别为HSP70和HSC70）。热休克蛋白与品系和适应温度之间的热耐受性差异有关；心脏和白色肌肉组织中的HSP70表现出相似的模式，而肝脏组织中的表达在适应温度之间有所不同，但在品系之间没有差异。综合来看，这些结果表明溪红点鲑种群应对气候变化的能力会有所不同。
