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

University Of Oregon Eugene, Eugene OR

Investigators

Abstract

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.