Experimental Evolutionary Studies of Temperature Adaptation

对环境变化的适应性进化反应的范围是什么？是否有一种通用的、可预测的、永远会出现的解决方案，还是有无数种不同的、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检查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，因为它控制着所有生物反应的速率，这些反应是二氧化碳产生、生长和繁殖等活动的基础。所有的种群一开始都是相同的克隆，但在长时间的连续培养过程中，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。在2000代之后，将首先分析其相对适合度和热耐受范围的差异，然后分析基因组成和表达的变化。研究人员将分析这些品系之间的差异，以确定是否存在适应的首选途径，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在单个基因水平上复制更多，以及适应度增量是否与基因表达变化的程度成正比。这个实验将创造一个前所未有的细菌谱系及其表达和序列数据的生物资源，这些数据将免费提供给科学界进行进一步分析。研究人员还将在当地高中教师的外展研讨会教育计划中使用该实验系统和该项目。本次研讨会将提供进化论的基本概念和微进化的例子的指导，这些概念和例子很容易理解和理解，并将进化论作为一种预测和假设检验的实验科学，这样它就可以在高中课堂上以一种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.