Nom du corpus

Corpus Systématique Animale

Titre du document

Multiple origins of anural development in ascidians inferred from rDNA sequences

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Springer (journals)
Langue(s) du document
Type de document
Mots-clés d'auteur
  • Ascidians
  • Larval development
  • 18S rDNA sequences
  • 28S rDNA sequences
  • Molecular phylogeny
  • Polyphyly
Nom du fichier dans la ressource
  • Kristen A. Hadfield 1,2
  • Billie J. Swalla 1,2
  • William R. Jeffery 1,2
  • 1) Bodega Marine Laboratory and Section of Molecular and Cellular Biology, University of California, Davis, P.O. Box 247, 94923, Bodega Bay, CA, USA
  • 2) Station Biologique, 29680, Roscoff, France

Ascidians exhibit two different modes of development. A tadpole larva is formed during urodele development, whereas the larval phase is modified or absent during anural development. Anural development is restricted to a small number of species in one or possibly two ascidian families and is probably derived from ancestors with urodele development. Anural and urodele ascidians constitute a model system in which to study the evolution of development, but the phylogeny of anural development has not been resolved. Classification based on larval characters suggests that anural species are monophyletic, whereas classification according to adult morphology suggests they are polyphyletic. In the present study, we have inferred the origin of anural development using rDNA sequences. The central region of 18S rDNA and the hypervariable D2 loop of 28S rDNA were amplified from the genomic DNA of anural and urodele ascidian species by the polymerase chain reaction and sequenced. Phylogenetic trees inferred from 18S rDNA sequences of 21 species placed anural developers into two discrete groups corresponding to the Styelidae and Molgulidae, suggesting that anural development evolved independently in these families. Furthermore, the 18S rDNA trees inferred at least four independent origins of anural development in the family Molgulidae. Phylogenetic trees inferred from the D2 loop sequences of 13 molgulid species confirmed the 18S rDNA phylogeny. Anural development appears to have evolved rapidly because some anural species are placed as closely related sister groups to urodele species. The phylogeny inferred from rDNA sequences is consistent with molgulid systematics according to adult morphology and supports the polyphyletic origin of anural development in ascidians.

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  • 1 - natural sciences
  • 2 - biology
  • 3 - evolutionary biology
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  • 1 - sciences appliquees, technologies et medecines
  • 2 - sciences biologiques et medicales
  • 3 - sciences biologiques fondamentales et appliquees. psychologie
Catégories Scopus
  • 1 - Life Sciences ; 2 - Biochemistry, Genetics and Molecular Biology ; 3 - Genetics
  • 1 - Life Sciences ; 2 - Biochemistry, Genetics and Molecular Biology ; 3 - Molecular Biology
  • 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - Ecology, Evolution, Behavior and Systematics
Catégories WoS
  • 1 - science ; 2 - genetics & heredity
  • 1 - science ; 2 - evolutionary biology
  • 1 - science ; 2 - biochemistry & molecular biology
Identifiant ISTEX

Journal of Molecular Evolution

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  • Batraciens
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