Email updates

Keep up to date with the latest news and content from Genome Biology and BioMed Central.

Open Access Highly Accessed Research

Comparative genomics reveals a constant rate of origination and convergent acquisition of functional retrogenes in Drosophila

Yongsheng Bai, Claudio Casola, Cédric Feschotte and Esther Betrán*

Author Affiliations

Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA

For all author emails, please log on.

Genome Biology 2007, 8:R11  doi:10.1186/gb-2007-8-1-r11

Published: 18 January 2007

Abstract

Background

Processed copies of genes (retrogenes) are duplicate genes that originated through the reverse-transcription of a host transcript and insertion in the genome. This type of gene duplication, as any other, could be a source of new genes and functions. Using whole genome sequence data for 12 Drosophila species, we dated the origin of 94 retroposition events that gave rise to candidate functional genes in D. melanogaster.

Results

Based on this analysis, we infer that functional retrogenes have emerged at a fairly constant rate of 0.5 genes per million years per lineage over the last approximately 63 million years of Drosophila evolution. The number of functional retrogenes and the rate at which they are recruited in the D. melanogaster lineage are of the same order of magnitude as those estimated in the human lineage, despite the higher deletion bias in the Drosophila genome. However, unlike primates, the rate of retroposition in Drosophila seems to be fairly constant and no burst of retroposition can be inferred from our analyses. In addition, our data also support an important role for retrogenes as a source of lineage-specific male functions, in agreement with previous hypotheses. Finally, we identified three cases of functional retrogenes in D. melanogaster that have been independently retroposed and recruited in parallel as new genes in other Drosophila lineages.

Conclusion

Together, these results indicate that retroposition is a persistent mechanism and a recurrent pathway for the emergence of new genes in Drosophila.