Journal Article

No Excess Gene Movement Is Detected off the Avian or Lepidopteran Z Chromosome

Melissa A. Toups, James B. Pease and Matthew W. Hahn

in Genome Biology and Evolution

Published on behalf of Society for Molecular Biology and Evolution

Volume 3, issue , pages 1381-1390
Published in print January 2011 |
Published online October 2011 | e-ISSN: 1759-6653 | DOI:

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  • Bioinformatics and Computational Biology
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Most of our knowledge of sex-chromosome evolution comes from male heterogametic (XX/XY) taxa. With the genome sequencing of multiple female heterogametic (ZZ/ZW) taxa, we can now ask whether there are patterns of evolution common to both sex chromosome systems. In all XX/XY systems examined to date, there is an excess of testis-biased retrogenes moving from the X chromosome to the autosomes, which is hypothesized to result from either sexually antagonistic selection or escape from meiotic sex chromosome inactivation (MSCI). We examined RNA-mediated (retrotransposed) and DNA-mediated gene movement in two independently evolved ZZ/ZW systems, birds (chicken and zebra finch) and lepidopterans (silkworm). Even with sexually antagonistic selection likely operating in both taxa and MSCI having been identified in the chicken, we find no evidence for an excess of genes moving from the Z chromosome to the autosomes in either lineage. We detected no excess for either RNA- or DNA-mediated duplicates, across a range of approaches and methods. We offer some potential explanations for this difference between XX/XY and ZZ/ZW sex chromosome systems, but further work is needed to distinguish among these hypotheses. Regardless of the root causes, we have identified an additional, potentially inherent, difference between XX/XY and ZZ/ZW systems.

Keywords: sex chromosome; duplication; retrogene

Journal Article.  7042 words. 

Subjects: Bioinformatics and Computational Biology ; Evolutionary Biology ; Genetics and Genomics

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