Pleiotropy, epistasis, and clonal interference in bacteriophage [Lower-case Greek phi]X174


Pepin, Kim M.. (2006). Pleiotropy, epistasis, and clonal interference in bacteriophage [Lower-case Greek phi]X174. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Pleiotropy, epistasis, and clonal interference in bacteriophage [Lower-case Greek phi]X174
Pepin, Kim M.
Bacteriophages Bacteriophage typing
The bacteriophage phi X174 is a useful model for examining the genetic basis of fitness and adaptation. The phage genome is small (5386 bases) such that specific genotypes can be constructed and described by genome sequencing. Its life cycle is short and simple. Fitness can be directly quantified as growth rate across generations. The exponential growth of large populations means that substantial evolutionary change occurs on a timescale observable by humans. The studies presented here take advantage of these unique experimental properties to examine how genetic properties of genomes and populations affect fitness and adaptive outcome.;The first two studies examined effects of single mutations on a phenotype and fitness. They showed that single mutations at the same two sites can have highly variable effects on fitness. Mutations showed remarkably variable levels of pleiotropy and epistasis. The contribution of these genetic interactions to determining fitness depended on host. The results emphasize that the genetic basis of fitness can not be neglected when predicting adaptive outcome, and environment can not be neglected when predicting effects of genotype on fitness. The third study examined how selection in different environments can affect the fixation probability of beneficial mutations in large populations through its effects on levels of standing genetic variation. These experiments showed that competition for fixation between beneficial mutations is frequent, suggesting that this type of interference should be considered when predicting adaptive outcome.
Thesis (Ph. D.)--University of Idaho, April 2006.
Major Professor:
Holly A. Wichman.
Defense Date:
April 2006.
Format Original:
vii, 124 leaves :ill. ;29 cm.

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