Hickey, Donal,Gao, Lifeng.2009-03-232009-03-2319991999Source: Masters Abstracts International, Volume: 37-06, page: 1775.9780612387508http://hdl.handle.net/10393/8490http://dx.doi.org/10.20381/ruor-7335Trypsin is a serine protease that functions as a digestive enzyme. It catalyzes the hydrolysis of peptide bonds specifically on the carboxyl side of lysine or arginine. It has been found that genes encoding this enzyme have evolved in a form of a gene family. Studies on the trypsin gene families from different species can help us understand the mechanism and process of molecular evolution. Previous studies have shown that the trypsin gene family in two sibling species, D. melanogaster and D. erecta diverged about 10 million years ago, and that they have the same genomic organization and patterns of molecular evolution. My work is mainly focused on the trypsin gene family in D. virilis, which diverged within the Drosophila lineage about 60 million years ago. The purpose of this thesis is to study the molecular evolution of this gene family in a time scale within the Genus of Drosophila. (Abstract shortened by UMI.)83 p.Biology, Molecular.Thesis