title: The coelacanth: Can a "living fossil" have active transposable elements in its genome?
abstract: The coelacanth has long been regarded as a "living fossil," with extant specimens looking very similar to fossils dating back to the Cretaceous period. The hypothesis of a slowly or even not evolving genome has been proposed to account for this apparent morphological stasis. While this assumption seems to be sustained by different evolutionary analyses on protein-coding genes, recent studies on transposable elements have provided more conflicting results. Indeed, the coelacanth genome contains many transposable elements and has been shaped by several major bursts of transposition during evolution. In addition, comparison of orthologous genomic regions from the genomes of the 2 extant coelacanth speciesL. chalumnaeandL. menadoensisrevealed multiple species-specific insertions, indicating transposable element recent activity and contribution to post-speciation genome divergence. These observations, which do not support the genome stasis hypothesis, challenge either the impact of transposable elements on organismal evolution or the status of the coelacanth as a "living fossil." Closer inspection of fossil and molecular data indicate that, even if coelacanths might evolve more slowly than some other lineages due to demographic and/or ecological factors, this variation is still in the range of a "non-fossil" vertebrate species.
authors.affiliation: Equipe "Génomique des Poissons"; Institut de Génomique Fonctionnelle de Lyon (UMR5242); Ecole Normale Supérieure de Lyon ; Lyon, France.
authors.forename: Magali
authors.initials: M
authors.lastname: Naville
authors.affiliation: Equipe "Génomique des Poissons"; Institut de Génomique Fonctionnelle de Lyon (UMR5242); Ecole Normale Supérieure de Lyon ; Lyon, France.
authors.forename: Domitille
authors.initials: D
authors.lastname: Chalopin
authors.affiliation: Equipe "Réseaux de gènes, développement, évolution" Laboratoire Evolution, Génomes, Comportement, Ecologie (UMR9191); Université Paris-Diderot; UFR des Sciences du vivant ; Paris, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Casane
authors.affiliation: Equipe "Réseaux de gènes, développement, évolution" Laboratoire Evolution, Génomes, Comportement, Ecologie (UMR9191); Université Paris-Diderot; UFR des Sciences du vivant ; Paris, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Laurenti
authors.affiliation: Equipe "Génomique des Poissons"; Institut de Génomique Fonctionnelle de Lyon (UMR5242); Ecole Normale Supérieure de Lyon ; Lyon, France.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Volff
keywords: coelacanth; evolution; fish; genome stasis; living fossil; tetrapods; transposable elements