Data from: Mechanisms of thermal adaptation and evolutionary potential of conspecific populations to changing environments

AbstractHeterogeneous and ever-changing thermal environments drive the evolution of populations and species, especially when extreme conditions increase selection pressure for traits influencing fitness. However, projections of biological diversity under scenarios of climate change rarely consider evolutionary adaptive potential of natural species. In this study, we tested for mechanistic evidence of evolutionary thermal adaptation among ecologically divergent redband trout populations (Oncorhynchus mykiss gairdneri) in cardiorespiratory function, cellular response and genomic variation. In a common garden environment, fish from an extreme desert climate had significantly higher critical thermal maximum (p<0.05) and broader optimum thermal window for aerobic scope (>3°C) than fish from cooler montane climate. In addition, the desert population had the highest maximum heart rate during warming (20% greater than montane populations), indicating improved capacity to deliver oxygen to internal tissues. In response to acute heat stress, distinct sets of cardiac genes were induced among ecotypes, which helps to explain the differences in cardiorespiratory function. Candidate genomic markers and genes underlying these physiological adaptations were also pinpointed, such as genes involved in stress response and metabolic activity (hsp40, ldh-b and camkk2). These markers were developed into a multi-variate model that not only accurately predicted critical thermal maxima, but also evolutionary limit of thermal adaptation in these specific redband trout populations relative to the expected limit for the species. This study demonstrates mechanisms and limitations of an aquatic species to evolve under changing environments that can be incorporated into advanced models to predict ecological consequences of climate change for natural organisms., Usage notescritical thermal maximumCTmax of three redband trout populations and a hybrid. Heating rate of water was 0.3°C min−1 to 22°C and 0.1°C min−1 thereafter until CTMAX was reached.maximum heart rateMaximum heart rate of three redband trout populations and a hybrid. Maximum heart rate was stimulated by an intraperitoneal injection of atropine sulfate and isoproterenol. Heating rate of water was 1 C every 6 minutes.metabolic rate and aerobic scopeStandard and maximum metabolic rate of three redband trout populations and a hybrid at 12°C, 15°C, 18°C, 21°C and 24°C. Maximum metabolic rate was achieved by exercise. Aerobic scope was calculated as the difference between standard and maximum rate.RAD TAG catelogRAD Tag sequence (75 bp ) and SNP position of the 5903 genetic markers.异质性且不断变化的热环境驱动种群与物种的演化，当极端环境加剧了影响适合度的性状的选择压力时，这一效应尤为显著。然而，气候变化情景下生物多样性的预测研究，极少考虑自然物种的演化适应潜力。本研究针对生态分化的红带鳟（Oncorhynchus mykiss gairdneri）种群，从心肺功能、细胞应答及基因组变异层面，检验了其演化热适应的机制性证据。 在共同花园实验环境中，源自极端荒漠气候的种群，其临界热最大值（critical thermal maximum, CTmax）显著更高（p<0.05），且有氧代谢范围的最优热窗口较凉爽山地气候种群宽3℃以上。此外，升温过程中荒漠种群的最大心率最高（较山地种群高20%），表明其向内部组织输送氧气的能力得到增强。 针对急性热应激，不同生态型诱导表达的心脏基因集存在差异，这为心肺功能的差异提供了解释。本研究还明确了这些生理适应背后的候选基因组标记与基因，例如参与应激响应与代谢活动的hsp40、ldh-b及camkk2。基于这些标记构建的多变量模型，不仅可精准预测临界热最大值，还能相较于该物种的预期上限，预测这些特定红带鳟种群的热适应演化极限。 本研究阐明了水生物种在环境变化下的演化机制与局限，该成果可纳入先进模型，以预测气候变化对自然生物的生态影响。 使用说明 1. 临界热最大值（critical thermal maximum, CTmax）：涉及3个红带鳟种群及1个杂交个体。水体升温速率为0.3℃·min⁻¹，升至22℃后调整为0.1℃·min⁻¹，直至达到临界热最大值。 2. 最大心率：涉及3个红带鳟种群及1个杂交个体。通过腹腔注射硫酸阿托品与异丙肾上腺素以诱导获得最大心率。水体升温速率为每6分钟升高1℃。 3. 代谢率与有氧代谢范围：在12℃、15℃、18℃、21℃及24℃下，测定3个红带鳟种群及1个杂交个体的标准代谢率与最大代谢率。最大代谢率通过运动诱导获得，有氧代谢范围以最大代谢率与标准代谢率的差值计算得到。 4. RAD Tag 目录：包含5903个遗传标记的RAD Tag序列（75 bp）与单核苷酸多态性（single nucleotide polymorphism, SNP）位点。