DISSERTATION RESEARCH: Testing for declining fitness and error catastrophe in adapting asexual populations

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Because the process of mutation introduces new genetic variation at random, it has been thought that too high a mutation rate will cause a population to go extinct. A phenomenon known as error catastrophe is predicted to occur when the mutation rate of a population surpasses the point at which the accumulation of mutations overpowers the strength of natural selection to maintain the fittest genotype. Recent work gives a quantitative prediction for the necessary relationship between genomic mutation rate and fitness variation in a population that will precipitate error catastrophe. In the current study we will conduct a detailed experimental characterization of a set of asexual bacterial populations engineered to have extraordinarily high mutation rates. These populations have been observed to decline to extinction in the laboratory, suggesting the occurrence of error catastrophe. The results may help explain the longstanding observation that many asexual populations are short-lived. In addition, the results may provide a basic science rationale for novel approaches to the treatment of viral and bacterial infections and cancers. This research is novel in that it is the first well-controlled experimental test of error catastrophe. This project is associated with several broad impacts. Two undergraduates and a high school student have contributed to the preliminary results. At present, one undergraduate at the University of Pennsylvania is directly involved in related research. Additionally, a pilot program is being launched in our department which will expose local high school students to research in the laboratory. This project combines both theoretical and experimental components that students of varying backgrounds may take interest in. The results of this project will likely may provide the basis for another undergraduate student?s thesis project which may ultimately produce published research.