Ubiquitous internal gene duplication and intron creation in eukaryotes

Xiang Gao, Michael Lynch

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Duplication of genomic segments provides a primary resource for the origin of evolutionary novelties. However, most previous studies have focused on duplications of complete protein-coding genes, whereas little is known about the significance of duplication segments that are entirely internal to genes. Our examination of six fully sequenced genomes reveals that internal duplications of gene segments occur at a high frequency (0.001-0.013 duplications/gene per million years), similar to that of complete gene duplications, such that 8-17% of the genes in a genome carry duplicated intronic and/or exonic regions. At least 7-30% of such genes have acquired novel introns, either because a prior intron in the same gene has been duplicated, or more commonly, because a spatial change has activated a latent splice site. These results strongly suggest a major evolutionary role for internal gene duplications in the origin of genomic novelties, particularly as a mechanism for intron gain.

Original languageEnglish (US)
Pages (from-to)20818-20823
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number49
StatePublished - Dec 8 2009
Externally publishedYes


  • Exons
  • Genome evolution
  • Intron evolution
  • Splice site

ASJC Scopus subject areas

  • General


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