DISSERTATION RESEARCH: Direct Tests of the Adaptive Benefits of Gene Exchange in Evolving Bacterial Populations

个体间的遗传交换是进化过程中最重要的贡献者之一。最近的DNA序列比较证据表明，细菌种群内的遗传交换频繁发生。本项目利用胃细菌幽门螺杆菌作为模型系统来解决两个有关原核生物中遗传交换的基本作用的问题。细菌种群内的基因交换是否会导致适应率的提高，以及它是否可以作为DNA修复的一种手段？为了检验这些假设，将在H.幽门螺杆菌，有和没有遗传交换，在适应实验室环境。细菌，包括H.幽门螺杆菌，对人类健康，农业系统和自然环境有重大影响。临床相关的表型，如抗生素耐药性，可以通过基因交换的一个实例在细菌之间传递。然而，目前尚不清楚这种交换事件是否代表特定选择压力所揭示的罕见事件，或者它们是否是一般原核生物适应机制的结果。了解这些生物体中遗传交换的基本作用将产生对这些系统中的种群和进化动力学的广泛见解。

Genetic exchange between individuals is one of the most important known contributors to evolutionary change.Recent evidence from the comparison of DNA sequences suggests that exchange frequently occurs within bacterial populations.This project utilizes the gastric bacterium Helicobacter pylori as a model system to address two questions concerning the fundamental role of genetic exchange in prokaryotes. Can genetic exchange within bacterial populations lead to increased rates of adaptation and can it function as a means for DNA repair? To test these hypotheses, fitness will be measured in populations of H. pylori, with and without genetic exchange, during adaptation in the laboratory environment. Bacteria, including H. pylori, have a major impact on human health, agricultural systems, and the natural environment. Clinically relevant phenotypes, such as antibiotic resistance, can be passed between bacteria by one instance of genetic exchange. It is not known, however, whether such exchange events represent rare occurrences revealed by specific selective pressures or whether they are the outcomes of a general prokaryotic adaptation mechanism. Understanding the fundamental role of genetic exchange in these organisms will yield broad insights into population and evolutionary dynamics in these systems.