Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)



First Advisor

Dr. Erin Schuenzel

Second Advisor

Dr. Matthew Terry

Third Advisor

Dr. Christopher Vitek


For this study, we will be looking to identify positive selection in eight genomes of the bacterial plant pathogen Xylella fastidiosa. A previous study used a branching method that identified 2 genes with positive selection along with a site-specific method identifying 34 genes showing positive selection. This current study focused specifically on the site-specific method, resulting in 28 genes (of 1,039 tested) showing positive selection. Of the 28 genes showing positive selection, 12 of them come from the pathogenicity, virulence and cellular structural categories. The remaining genes are found in the biosynthesis, metabolism, macro metabolism, and cellular process categories. Not only does using this type of model help us in understanding the role of selection on a gene in this bacteria, but by using the Selecton website to run the sequences we can also see in which location on the protein the selection is taking place, therefore allowing us to find the specific codon of the gene in which positive selection is taking place. It also allows us to identify other genes that show changes taking place on a specific codon of the gene but may not be showing positive selection as a whole.


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