A Molecular Phylogenetic Framework for the Phylum Ctenophora Using 18S rRNA Genes

✍ Scribed by Mircea Podar; Steven H.D. Haddock; Mitchell L. Sogin; G.Richard Harbison

• Book ID: 102614913
• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 327 KB
• Volume: 21
• Category: Article
• ISSN: 1055-7903
• DOI: 10.1006/mpev.2001.1036

✦ Synopsis

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.