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

Authors: Podar M.¹; Haddock S.H.D.²; Sogin M.L.³; Harbison G.R.⁴

Source: Molecular Phylogenetics and Evolution, Volume 21, Number 2, November 2001 , pp. 218-230(13)

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Abstract:

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. Copyright 2001 Academic Press.

Language: English

Document Type: Research article

Affiliations: 1: Department of Molecular Diversity, Diversa Corp., 4955 Directors Place, San Diego, California, 92121 2: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, California, 95039 3: Marine Biological Laboratory, 7 MBL Street, Woods Hole, Massachusetts, 02543 4: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543

Publication date: 2001-11-01