Long-term Research in Environmental Biology (LTREB): Rapid evolution of a Threespine Stickleback Population

进化史通常是通过比较数千到数百万代以前拥有共同祖先的物种来研究的，但进化过程的研究相对较少。因此，从过程研究中得出的结论必须通过时间和物种来解释历史。本项目利用独特的棘鱼研究系统，直接整合棘鱼的进化历史和过程。20世纪80年代，一群海流棘鱼在阿拉斯加的一个湖泊定居，随后经历了快速的进化。1990年首次取样时，它在身体形状和大小、鳃盖形状、甲壳、进食结构以及控制甲壳和调节体液中盐浓度的基因方面与海刺鱼非常相似。每年的采样显示，每一种特征都朝着较老的湖泊种群逐渐进化变化，现在几乎无法区分。该项目将继续对该湖泊种群进行长期研究，并扩大研究淡水湖中普遍存在的疾病病原体对鱼类免疫的演变的工作。该项目还启动了对其他海流棘鱼种群的新研究，这些种群处于淡水湖泊殖民的最早阶段。这些海洋种群的进化模拟了自上一个冰河时代以来无数淡水种群的进化历史。该研究对于预测鱼类在全球气候变化和商业物种的密集捕捞压力下的适应性具有更广泛的意义。它还将提供有关对新发传染病免疫反应演变的宝贵信息。该项目为本科生提供了动手研究经验。该项目的数据将每年发布在一个公众可访问的网站上，记录鱼类快速进化的时间序列将被存放在耶鲁皮博迪博物馆，以供进一步研究。

Evolutionary history is generally studied by comparing species that shared a common ancestor thousands to millions of generations ago, but evolutionary processes are studied over relatively few generations. Hence, conclusions from studies on processes must be extrapolated through time and among species to interpret history. This project makes use of a unique study system involving the stickleback fish, in order to directly integrate evolutionary history and process. A sea-run stickleback population colonized an Alaskan lake in the 1980's and subsequently underwent rapid evolution. When first sampled in 1990, it closely resembled sea-run sticklebacks in body shape and size, the shape of the gill cover, armor plates, feeding structures, and the genes that control armor and regulate the salt concentration in body fluids. Annual sampling revealed progressive evolutionary change of every trait towards those of older lake populations, from which it is now almost indistinguishable. This project will continue the long term study of this lake population, and expand the work to study the evolution of fish immunity to disease agents that are prevalent in freshwater lakes. This project also initiates new research on additional sea-run stickleback populations that are at the earliest stages of colonization of freshwater lakes. Evolution of these sea-run populations simulates the history by which countless freshwater populations have evolved since the last ice age. This study has broader relevance to predicting the adaptability of fish species in the face of global climate change and intensive fishing pressure on commercial species. It will also provide valuable information on the evolution of immune response to emerging infectious disease. The project gives undergraduate students hands-on research experience. Data from this project will be posted annually on a publically accessible website, and the time series of fish collections documenting rapid evolution will be deposited in the Yale Peabody Museum for further study.