title: Ubiquitous internal gene duplication and intron creation in eukaryotes.
abstract: 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.
authors.affiliation: Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA. gao3@indiana.edu
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.forename: Michael
authors.initials: M
authors.lastname: Lynch
mesh_terms: D000818:Animals; D018076:DNA, Complementary / Q000235:genetics; D056890:Eukaryota / Q000235:genetics*; D020440:Gene Duplication; D006207:Half-Life; D007438:Introns / Q000235:genetics*; D022821:RNA Splice Sites / Q000235:genetics; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D022821:RNA Splice Sites