A molecular phylogenetic framework for the phylum Ctenophora using 18S rRNA genes

Mol Phylogenet Evol. 2001 Nov;21(2):218-30. doi: 10.1006/mpev.2001.1036.


This paper presents the first molecular phylogenetic analysis of the phylum Ctenophora, by use of 18S ribosomal RNA sequences from most of the major taxa. The ctenophores form a distinct monophyletic group that, based on this gene phylogeny, is most closely related to the cnidarians. Our results suggest that the ancestral ctenophore was tentaculate and cydippid-like and that the presently recognized order Cydippida forms a polyphyletic group. The other ctenophore orders that we studied (Lobata, Beroida, and Platyctenida) are secondarily derived from cydippid-like ancestors, a conclusion that is also supported by developmental and morphological data. The very short evolutionary distances between characterized ctenophore 18S rRNA gene sequences suggests that extant ctenophores are derived from a recent common ancestor. This has important consequences for future studies and for an understanding of the evolution of the metazoans.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • DNA / chemistry
  • DNA / genetics
  • DNA, Ribosomal Spacer / genetics
  • Evolution, Molecular
  • Invertebrates / classification
  • Invertebrates / genetics*
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Phylogeny*
  • RNA, Ribosomal, 18S / chemistry
  • RNA, Ribosomal, 18S / genetics*
  • RNA, Ribosomal, 5.8S / genetics
  • Sequence Analysis, DNA


  • DNA, Ribosomal Spacer
  • RNA, Ribosomal, 18S
  • RNA, Ribosomal, 5.8S
  • DNA

Associated data

  • GENBANK/AF293673
  • GENBANK/AF293674
  • GENBANK/AF293675
  • GENBANK/AF293676
  • GENBANK/AF293677
  • GENBANK/AF293678
  • GENBANK/AF293679
  • GENBANK/AF293680
  • GENBANK/AF293681
  • GENBANK/AF293682
  • GENBANK/AF293683
  • GENBANK/AF293684
  • GENBANK/AF293685
  • GENBANK/AF293686
  • GENBANK/AF293687
  • GENBANK/AF293688
  • GENBANK/AF293689
  • GENBANK/AF293690
  • GENBANK/AF293691
  • GENBANK/AF293692
  • GENBANK/AF293693
  • GENBANK/AF293694
  • GENBANK/AF293695
  • GENBANK/AF293696
  • GENBANK/AF293697
  • GENBANK/AF293698
  • GENBANK/AF293699
  • GENBANK/AF293700
  • GENBANK/AY039208
  • GENBANK/AY039209