Evolution of increased mutation rates in asexual populations : causes and consequences / Aaron Corydon Shaver.

Format:

Book

Manuscript

Microformat

Thesis/Dissertation

Author/Creator:

Shaver, Aaron Corydon.

Contributor:

Sniegowski, Paul D., advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Penn dissertations--Biology.

Biology--Penn dissertations.

Biology.

Academic Dissertations as Topic.

Medical Subjects:

Biology.

Academic Dissertations as Topic.

Local Subjects:

Penn dissertations--Biology.

Biology--Penn dissertations.

Physical Description:

xi, 169 pages : illustrations ; 29 cm

Production:

2003.

Summary:

The rate at which mutations arise is under the control of complex biological systems, and is thus subject to adjustment by natural selection. The effects of beneficial and deleterious mutations counter exert opposing forces on the direction of such selection; understanding the balance of these forces is key to understanding the evolution of mutation rates. This work concentrates on understanding the processes that result in the evolution of high mutation rates in asexual populations. An in-depth study is made of the population dynamics surrounding the fixation of three different alleles conferring high mutation rates in experimental bacterial populations. The results of this study are consistent with the hypothesis that high mutation rates evolved, not because of any inherent fitness advantage to the phenotype, but because of fortuitous association with other mutations of beneficial effect. Two of the three alleles studied were found to have arisen independently in a small repeat region within the same DNA repair gene; while the coincidence is striking, analysis of the repeat region as well as the nature of selective dynamics in asexual populations make it extremely unlikely that the DNA repeat has been maintained by selection to provide a region of hypervariability. Other work described here includes an experimental analysis of the dynamics of adaptation in populations of high versus low mutation supply rates; a theoretical treatment of the effect of environment-specific changes in mutation rate on the accumulation of deleterious load during times of physiological stress; and a simulation-based analysis of the estimation of mutation rates from experimental data when the data are subjected to realistic levels of noise and distortion.

Notes:

Adviser: Paul D. Sniegowski.

Thesis (Ph.D. in Biology) -- University of Pennsylvania, 2003.

Includes bibliographical references.

Local Notes:

University Microfilms order no.: 3095939.

OCLC:

244973666