COLLABORATIVE RESEARCH: Parallel and non-parallel evolution at multiple levels: environment, selection, phenotype, and genotype

进化生物学中的一个基本难题是进化是否可重复：如果许多相同的初始种群暴露在同一类型的新环境中，它们是否都会进化出相同的适应性？这些适应性变化是由相同的潜在基因的变化引起的吗？本研究项目的目的是回答这两个问题，使用一种小鱼，三棘鱼，作为研究对象。大约12,000年前冰川融化时，同样的海洋生活形式的棘鱼在许多不同的河流流域定居，提供了一个自然发生的实验来测试进化的可重复性。研究人员将测量相邻湖泊和溪流种群之间的环境，形态和遗传差异，这些种群来自16个流域中的每一个，代表了进化的湖泊-溪流差异的单独实例。然后，他们将应用最先进的统计分析来衡量湖泊和溪流类型之间的差异在多大程度上重复演变，或者是每个流域所独有的。遗传分析将揭示重复的形态差异在多大程度上是由相同基因的进化变化引起的。该项目将揭示如何预测进化变化的一般原则，并开创相关的统计方法。这些原则和方法对于预测害虫或疾病如何对农药或药物作出反应，或者物种如何适应气候变化至关重要。此外，该项目还将把领先的生物学研究人员与高中生物学教师和职前培训教师配对，为K-12科学教师提供涉及进化生物学基本原理的实践研究经验。

A fundamental puzzle in evolutionary biology is whether evolution is repeatable: if many identical starting populations were exposed to the same type of novel environment, would they all evolve the same adaptations? Would the adaptations result from changes in the same underlying genes? This research project aims to answer both questions using a small fish, the threespine stickleback, as a study subject. The same ocean-dwelling form of stickleback colonized many separate river basins when the glaciers melted ~12,000 years ago, providing a naturally occurring experiment to test the repeatability of evolution. The researchers will measure environmental, morphological, and genetic divergence between adjacent lake and stream populations of stickleback, from each of 16 watersheds that represent separate instances of evolved lake-stream differences. They will then apply state-of-the-art statistical analyses to measure the extent to which differences between lake and stream types have evolved repeatedly or are unique to each watershed. Genetic analysis will reveal the extent to which repeated morphological differences result from evolutionary changes in the same genes. The project will reveal general principles of how predictable evolutionary change is, and pioneer relevant statistical methods. Such principles and methods are vital to anticipating how pests or diseases may evolve in response to pesticides or drugs, or how species will adapt to climate change. In addition, the project will pair up leading biological researchers with high-school biology teachers and pre-service teachers-in-training, giving K-12 science teachers practical research experience involving fundamental principles of evolutionary biology.