The evolutionary demography of duplicate genes

Michael Lynch, John S. Conery

Research output: Contribution to journalReview article

216 Scopus citations

Abstract

Although gene duplication has generally been viewed as a necessary source of material for the origin of evolutionary novelties, the rates of origin, loss, and preservation of gene duplicates are not well understood. Applying steady-state demographic techniques to the age distributions of duplicate genes censused in seven completely sequenced genomes, we estimate the average rate of duplication of a eukaryotic gene to be on the order of 0.01/ gene/million years, which is of the same order of magnitude as the mutation rate per nucleotide site. However, the average half-life of duplicate genes is relatively small, on the order of 4.0 million years. Significant interspecific variation in these rates appears to be responsible for differences in species-specific genome sizes that arise as a consequence of a quasi-equilibrium birth-death process. Most duplicated genes experience a brief period of relaxed selection early in their history and a minority exhibit the signature of directional selection, but those that survive more than a few million years eventually experience strong purifying selection. Thus, although most theoretical work on the gene-duplication process has focused on issues related to adaptive evolution, the origin of a new function appears to be a very rare fate for a duplicate gene. A more significant role of the duplication process may be the generation of microchromosomal rearrangements through reciprocal silencing of alternative copies, which can lead to the passive origin of post-zygotic reproductive barriers in descendant lineages of incipient species.

Original languageEnglish (US)
Pages (from-to)35-44
Number of pages10
JournalJournal of Structural and Functional Genomics
Volume3
Issue number1-4
DOIs
StatePublished - Apr 30 2003
Externally publishedYes

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Keywords

  • Gene duplication
  • Genome evolution
  • Genome size

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Genetics

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