Table of Contents
International Journal of Evolutionary Biology
Volume 2013 (2013), Article ID 693085, 12 pages
http://dx.doi.org/10.1155/2013/693085
Research Article

Evolution of Three Parent Genes and Their Retrogene Copies in Drosophila Species

Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB, Canada E3B 5A3

Received 28 February 2013; Accepted 8 May 2013

Academic Editor: Shozo Yokoyama

Copyright © 2013 Ryan S. O'Neill and Denise V. Clark. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Retrogenes form a class of gene duplicate lacking the regulatory sequences found outside of the mRNA-coding regions of the parent gene. It is not clear how a retrogene’s lack of parental regulatory sequences affects the evolution of the gene pair. To explore the evolution of parent genes and retrogenes, we investigated three such gene pairs in the family Drosophilidae; in Drosophila melanogaster, these gene pairs are CG8331 and CG4960, CG17734 and CG11825, and Sep2 and Sep5. We investigated the embryonic expression patterns of these gene pairs across multiple Drosophila species. Expression patterns of the parent genes and their single copy orthologs are relatively conserved across species, whether or not a species has a retrogene copy, although there is some variation in CG8331 and CG17734. In contrast, expression patterns of the retrogene orthologs have diversified. We used the genome sequences of 20 Drosophila species to investigate coding sequence evolution. The coding sequences of the three gene pairs appear to be evolving predominantly under negative selection; however, the parent genes and retrogenes show some distinct differences in amino acid sequence. Therefore, in general, retrogene expression patterns and coding sequences are distinct compared to their parents and, in some cases, retrogene expression patterns diversify.