Experimental Evolutionary Studies of Temperature Adaptation

适应性进化对环境变化的反应范围是什么？ 是有一个共同的、可预测的解决方案总是会出现，还是有无数不同的、因此不可预测的适应方式？ 研究人员将使用实验进化技术来研究100个大肠杆菌种群对高温的进化反应。 温度是一个至关重要的环境变量，因为它控制着二氧化碳产生、生长和繁殖等活动的所有生物反应的速率。 所有的种群都是从相同的克隆开始的，但是在扩展的连续培养过程中的突变会产生遗传变化，这些变化可能会被自然选择所青睐或消除。 2000代后，将分析反应的多样性，首先是它们的相对适合度和耐热范围的差异，然后是基因组成和表达的变化。 将分析品系之间的差异，以确定是否存在优选的适应途径，以及这些途径是否涉及调控基因，进化是否在功能类别水平上比单个基因更多地复制，以及适应性增量是否与基因表达的变化程度成比例。 这项实验将为细菌谱系及其表达和序列数据创造前所未有的生物资源，这些数据将免费提供给科学界进行进一步分析。 研究人员还将使用这个实验系统和这个项目在一个推广讲习班教育计划，为当地高中教师。 该研讨会将提供进化的基本概念和微进化的例子，这些例子是立即可访问和易于理解的，并将进化作为一种预测和假设测试实验科学，以便它可以在高中课堂上以较少争议的方式解释。

What is the range of adaptive evolutionary responses to environmental change? Is there a single common, predictable solution that will always occur or a myriad of different and therefore unpredictable ways of adapting? The investigators will use the techniques of experimental evolution to examine the evolutionary responses of one hundred populations of the bacterium Escherichia coli to high temperature. Temperature is a crucial environmental variable because it controls the rates of all biological reactions that underlie such activities as carbon dioxide production, growth, and reproduction. All populations will start as identical clones, but mutations during extended serial culture will produce genetic changes which may be favored or eliminated by natural selection. After 2000 generations, the diversity of responses will be analyzed, first for differences in their relative fitness and their thermal tolerance range, then for changes in gene composition and expression. The differences among the lines will be analyzed to determine if there are preferred pathways of adaptation and whether these involve regulatory genes, whether evolution is more replicated at the level of functional category than individual gene, and whether fitness increment is proportional to the extent of change in gene expression. This experiment will create an unprecedented biological resource of both the bacterial lineages and their expression and sequence data, which will be made freely available to the scientific community for further analyses. The investigators will also use this experimental system and this project in an outreach workshop education program for local high school teachers. This workshop will provide instruction in basic concepts in evolution and examples of microevolution that are immediately accessible and easily comprehensible and present evolution as a predictive and hypothesis-testing experimental science, so that it can be explained in the high school classroom in a less controversial way.