The role of epigenetics in rapid environmental adaptation: How do threespine stickleback fish in Californian bar-built estuaries rapidly adapt to seasonal salinity changes?

由于全球变暖的影响，许多动物物种面临灭绝的威胁，除非它们能够适应。进化论解释了物种是如何通过DNA的变化而出现和适应的。这一过程需要许多代人的时间，在气候变化面前可能太慢了。然而，许多物种表现出非凡的适应环境挑战的能力，表明存在更快速的机制。了解这些快速适应反应可以帮助我们预测和减轻气候变化的影响，并制定保护策略。我们正在研究三刺鱼种群的适应性，这些种群生活在加利福尼亚的酒吧河口。与大多数生活在海洋或淡水中的刺鱼不同，这些鱼能在从淡水到咸水的季节性波动中存活下来。我们假设对季节波动的适应依赖于表观遗传调节。表观遗传调控并不依赖于DNA突变的遗传（即进化），而是控制现有DNA（基因组）的使用方式。基因构成了基因组的基本单位，每个单位都包含了制造一种蛋白质所需的信息。这些蛋白质是细胞和组织的结构和功能成分。这包括作为分子传感器和机器的蛋白质，它们可以探测和响应环境条件（比如水中有多少盐）。生物体适应环境变化的一种方法是，如果它们能够存储传感器收集的信息，并利用这些信息来调整分子机器（如从细胞中去除多余盐分的泵），从而对这些信息做出反应——本质上是为未来做准备。这可以通过控制特定基因输出的表观遗传调控来实现。在分子水平上，表观遗传调控改变了基因组的组织方式，标记出基因输出的增加或减少。我们的项目将分析鳃细胞中的基因组，以测试表观遗传调控是否可以解释这些鱼如何适应波动的环境。鱼类对水生生态系统至关重要，也是人类的食物来源。我们的工作可能有助于了解鱼类如何适应环境变化。

Many animal species are threatened with extinction from the effects of global warming unless they can adapt. Evolution explains how species emerge and adapt through changes in their DNA. This process takes place over many generations, which may be too slow in the face of climate change. However, many species show remarkable ability to adapt to environmental challenges, indicating that there are more rapid mechanisms. Understanding these rapid adaptation responses may allow us to predict and mitigate effects of climate change and develop conservation strategies. We are studying adaptation in threespine stickleback fish populations in Californian bar-built estuaries. Unlike most stickleback populations that reside in either marine or fresh water, these fish survive seasonal fluctuations from fresh to saltwater. We hypothesize that adaptation to seasonal fluctuations relies on epigenetic regulation. Epigenetic regulation does not depend on inheritance of DNA mutations (i.e. evolution), but instead controls how the existing DNA (genome) is used. Genes form the basic units of the genome, that each contain information needed to make one protein. These proteins are the structural and functional components of cells and tissues. This includes proteins that are molecular sensors and machines that detect and respond to environmental conditions (such as how much salt is in the water). One way organisms may adapt to changes in their environment is if they can store information collected by sensors, and use it to adjust the molecular machines (such as pumps that remove excess salt from cells) that respond to it-essentially preparing for the future. This could occur through epigenetic regulation that controls the output of specific genes. At the molecular level, epigenetic regulation changes how the genome is organized, marking genes for increased or decreased output. Our project will analyse the genome in gill cells to test whether epigenetic regulation can explain how these fish adapt to their fluctuating environment. Fish are essential to the aquatic ecosystem, and to the human population as a food source. Our work may help to understand how fish can adapt to environmental change.