Mechanisms of environmental adaptation in fish

温度影响着各个层次的生物过程，从单个分子到单个有机体，再到整个生态系统。因此，温度是影响所有物种，特别是鱼类等外温动物的分布和丰度的关键因素。然而，尽管经过几十年的研究，我们仍然没有完全了解鱼类在其一生中如何应对环境温度的变化，或者在进化过程中如何适应环境温度。在这里，我们建议使用两种小鱼（鱼和棘鱼）作为模型来解决这些问题。我们以前已经表明，每个物种内的种群之间存在与热生物学相关的各种特征的变化，例如它们可以忍受的温度。 北方群体的静息代谢率也高于南方群体，这可能是对北方纬度低温和短生长季节的一种适应。此外，北方群体的鳉鱼能够增加其细胞中线粒体（一种能量产生结构）的数量，以应对寒冷的温度，而南方群体的鳉鱼则不能进行这种补偿反应。 在这里，我们建议使用尖端的基因组方法结合详细的生化和生理分析，以了解导致这种种内变化的热生物学机制。具体来说，我们将测试线粒体特性的变化与静息代谢率的变化有关的假设，并询问是否有任何其他过程也有助于这种变化。然后，我们将研究线粒体数量变化的机制，以应对低温，以及导致温度耐受性差异的机制。这项研究将为短期和长期尺度上对温度变化的遗传，生理和分子机制提供新的见解。考虑到全球气候变化可能产生的影响，了解这些机制在今天尤为重要。

Temperature affects biological processes at all levels of organization from individual molecules, to individual organisms, to whole ecosystems. Temperature is thus critical factor influencing the distribution and abundance of all species, and particularly of ectotherms such as fish. Despite several decades of study, however, we still do not have a complete understanding of how fish respond to changes in environmental temperature during their lifetimes, or how adaptation to environmental temperature occurs over evolutionary time. Here we propose to use two species of small fish (killifish and stickleback) as models to address these questions. We have previously shown that there is variation among populations within each species in a variety of characteristics related to thermal biology, such as the temperatures they can tolerate. Northern populations of killifish also have higher resting metabolic rate than do southern populations, which may be an adaptation to the low temperatures and short growing seasons of northern latitudes. In addition, northern populations of killifish are able to increase the amount of mitochondria (an energy producing structure) in their cells in response to cold temperatures, while killifish from southern populations cannot mount this compensatory response. Here we propose to use cutting edge genomic methods combined with detailed biochemical and physiological analyses to understand the mechanisms that cause this intraspecific variation in thermal biology. Specifically, we will test the hypothesis that variation in mitochondrial properties is related to variation in resting metabolic rate, and ask whether any other processes also contribute to this variation. We will then examine the mechanisms responsible for variation in the amounts of mitochondria in response to low temperature, and the mechanisms that cause differences in temperature tolerance. Together this research will provide novel insights into the genetic, physiological and molecular mechanisms underlying responses to temperature changes on both short and long time scales. Understanding these mechanisms is particularly relevant today given the likely effects of global climate change.