Document Type

Thesis

Date of Degree Completion

Spring 2008

Degree Name

Bachelor of Science

Department

Biology

Committee Chair

Dr. L. A. Raubeson, Department of Biological Sciences

Second Committee Member

Dr. J. E. Johnson, Department of Biological Sciences

Third Committee Member

Dr. Audrey D. Huerta, Director Science Honors Research Program

Abstract

The conservative nature of the copy variable region (CVR) of the chloroplast genome, also known as the inverted repeat (IR) region, is well established; however the basis for the lower mutation rate has been debated. Two ideas have been proposed to explain the reduced rate: 1) genes in the region are inherently slow to evolve; or 2) the presence of two copies reduces the rate via copy correction. Comparisons of eighty-three genes and twenty introns were made estimating mutation rates, from both the CVR region and single copy (SC) regions in legumes and gymnosperms. In gene and intron comparisons, CVR and SC rates from genomes containing two CVR copies and genomes containing one CVR copy were compared. Synonymous and nonsynonymous substitution rates, average distances and Tajima's Relative Rate Test support the conclusion that the reduced CVR mutation rate is due to the presence of two copies. Copy correction between copies is the most likely mechanism for the sequence conservation observed in the CVR when two copies are present.

Comments

This thesis has been digitized and made available as part of the University’s ongoing preservation and access initiatives. Copyright is retained by the original author. The University has made a good faith effort to review this work for copyright and privacy concerns prior to digitization. If you are the author or a rights holder and have questions, concerns or wish to request removal, please contact ScholarWorks@cwu.edu.

Download

Share

COinS