The streams draining volcanic landscapes are often characterized by a complex series of factors that negatively affect hydrobionts and lead to declines in their populations. However, in a number of cases, a range of rapid adaptive changes ensure the resilience of hydrobiont populations. Here, we present both field and experimental data shedding light on the physiological basis of adaptation to heavy metal contamination in populations of Dolly Varden charr (Salvelinus malma) differing in duration of isolation in volcanic streams. The study reveals that isolated populations have a physiological phenotype that distinguishes them from populations inhabiting clean waters. They are characterized by a hyperthyroid status accompanied by an increased metabolic rate, elevated activity of antioxidant enzymes, decreased ionic conductivity of tissues and reduced stored energy reserves. Our experimental data reveal that hyperthyroidism is an adaptive characteristic enhancing the resistance to heavy metal contamination and shaping the evolution of these populations. The similarity of physiological, developmental and morphological changes in isolated populations suggests a common source and mechanisms underpinning this case of 'evolutionary rescue'. Thus, populations of S. malma trapped in volcanic streams represent a genuine case of rapid endocrine-driven adaptation to changing environmental stimuli.

中文翻译：

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甲状腺机能亢进引起鲑鱼对环境污染的快速适应。

排出火山地貌的溪流通常具有一系列复杂的因素，这些因素对水生生物产生负面影响并导致其数量下降。然而，在许多情况下，一系列快速的适应性变化确保了水生生物种群的恢复能力。在这里，我们提供了现场和实验数据，揭示了多莉瓦尔登红点鲑（Salvelinus malma）种群适应重金属污染的生理基础，这些红点鲑在火山流中的隔离时间不同。该研究表明，孤立的种群具有与居住在清洁水域的种群不同的生理表型。它们的特征是甲状腺功能亢进状态，伴有代谢率增加、抗氧化酶活性升高、组织离子电导率降低和储存能量储备减少。我们的实验数据表明，甲状腺功能亢进症是一种适应性特征，可增强对重金属污染的抵抗力并塑造这些人群的进化。孤立群体的生理、发育和形态变化的相似性表明支撑这种“进化拯救”案例的共同来源和机制。因此，被困在火山溪流中的马尔马种群代表了内分泌驱动的快速适应不断变化的环境刺激的真实案例。