Tempereature tolerance and developmental phenotypic plasticity in early life stage fish

全球气候变化正在造成全球河流系统温度升高的大趋势。因此，由人类活动引起的当地水生环境温度升高可能会对这些生态系统中的鱼类产生强烈的选择压力。动物如何应对环境的变化将预测种群对这些未来条件的反应。虽然我们对鱼类对变暖和变冷的急性反应了解很多，但我们对热历史如何促进生理调节，从而保护鱼类免受慢性变暖或偶发性变暖事件的影响知之甚少。我的研究项目侧重于早期生命阶段鱼类的表型反应，以及暴露于高温下如何增强对未来热挑战的保护。为了解决这个问题，我打算描述幼虫和幼鱼在发育过程中获得的热保护的大小和时间，以及预暴露于温度升高的结果。我还将描述在不同的热环境下饲养的鱼卵或幼鱼时，永久性热保护的比例（即，发育可塑性的结果，而不是通过适应）。然后，在更广泛的生活史特征背景下，检查这种对高温的表型可塑性，我将测试这样一个假设，即鱼类较长的世代时间将与可逆表型的倾向相关，因为永久适应当前条件的选择压力可能较小。在不列颠哥伦比亚省，人们对长寿的原始鲟鱼和寿命较短但在生态和经济上具有重要意义的鲑鱼都很感兴趣，它们是西海岸社会和文化的象征。在这里概述的研究中，我将重点关注这两种鱼类，鲟鱼和鲑鱼，因为这些溯河洄游鱼类有着截然不同的生活史策略，这可能导致了不同的耐热性方法。这项工作将提供知识，有助于保护地方性种群，减轻气候变化对不列颠哥伦比亚省具有重大文化、社会经济和生态价值的物种的影响。温哥华岛大学独特、先进的RAS设施和地理位置非常适合开始这项工作，在五年的时间里，我打算培养7名本科生、2名硕士生和1名博士生。

Global climate change is contributing to a general trend of increased temperatures in river systems worldwide. Consequently, temperature increases in local aquatic environments driven by human sources may be inducing intense selection pressures on fish in these ecosystems. How animals cope with changes in their environment will predict how populations respond to these future conditions. While we understand a great deal about acute responses to warming and cooling in fish, we know much less about how thermal history might promote physiological adjustments that result in protection from chronic warming or episodic heating events. My research program focuses on the phenotypic responses of early life stage fish, and how exposure to elevated temperature may enhance protection from future thermal challenge. To address this, I intend to characterize the magnitude and timing of thermal protection acquired during development of larvae and juvenile fish, and as a result of pre-exposure to increased temperatures. I will also describe the proportion of thermal protection that is permanent (i.e., a result of developmental plasticity, as opposed to through acclimation) when eggs or larval fish are reared under different thermal regimes. Examining, then, this phenotypic plasticity to elevated temperatures over the broader context of life history characteristics, I will test the hypothesis that longer generational times in fish will be associated with a propensity for reversible phenotypes, as there may be less selective pressure to permanently adjust to current conditions. In BC, there is great interest in both the long-lived, primitive sturgeons, and more ephemeral, but hugely ecologically and economically important salmonids, that represent social and cultural icons on the West Coast. For the studies outlined here, I will focus on these two groups, sturgeon and salmon, as these anadromous, migratory fishes have substantially different life history strategies that may have contributed to different approaches to thermal tolerance. This work will provide knowledge that will help protect endemic stocks and mitigate climate change effects on species with great cultural, socioeconomic and ecological value to British Columbians. The unique, cutting-edge RAS facilities and location of Vancouver Island University are exceptionally well suited to begin this work, and over the course of five years, I intend to train 7 undergraduates, 2 M. Sc. students, and a Ph.D. student.