Evidence for de novo evolution of testis-expressed genes in the Drosophila yakuba/Drosophila erecta clade

¹ University of California, Davis
² University of California, Santa Cruz
³ University of North Carolina

^* To whom correspondence should be addressed. E-mail: djbegun{at}ucdavis.edu.

Submitted on December 4, 2006
Revised on February 14, 2007
Accepted on 11 April 2007

	Abstract

The mutational origins and selective agents causing fixation of de novo genes, recently evolved genes that are not obviously related to ancestral coding sequence, is mysterious. However, accumulating evidence suggests that male reproductive functions are likely to be enriched for such genes. Here we use testis-derived expressed sequence tags (ESTs) from D. yakuba to investigate to identify testis-biased genes that have likely arisen either in D. yakuba or in the D. yakuba/D. erecta ancestor. We found several such genes, which are overrepresented on the X chromosome. Comparative data suggests that three of these genes have very short open reading frames, which suggests the possibility that a significant number of testis-biased de novo genes in the D. yakuba/D. erecta clade may be noncoding RNA genes. During the course of this work, we also identified a number of rapidly evolving testis-biased genes that are likely present in several melanogaster subgroup species. These data along with previously published data from D. melanogaster, support the idea that many de novo genes function in male reproduction and that a small region of the X chromosome in the melanogaster subgroup is a hotspot for the evolution of novel testis-biased genes.

Key Words: de novo genes, male reproduction, novel genes, testis

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