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Citation for Study 1970

About Citation title: "Multi-gene analyses of phylogenetic relationships between Mollusca, Annelida and Arthropoda".
About This study was previously identified under the legacy study ID S1953 (Status: Published).


Colgan D., Hutchings P., & Beacham E. 2007. Multi-gene analyses of phylogenetic relationships between Mollusca, Annelida and Arthropoda. Zoological Studies, null.


  • Colgan D.
  • Hutchings P.
  • Beacham E.


The current understanding of metazoan relationships is largely based on analyses of 18S rRNA. In this paper, DNA sequence data from two segments of 28S rRNA, cytochrome c oxidase subunit I, histone H3 and U2 snRNA are compiled and used to test the phylogenetic relationships between Mollusca, Annelida and Arthropoda. 18S rRNA data were included in the compilations for comparison. The analyses were especially directed to testing the implication of the Eutrochozoa hypothesis that Annelida and Mollusca are more closely related than Annelida and Arthropoda and at determining whether, in contrast to analyses using only18S rRNA, the addition of data from other genes find these phyla monophyletic. New data and available sequences were compiled for up to 49 molluscs, 33 annelids, 22 arthropods, and 27 taxa from fifteen other metazoan phyla. Porifera, Ctenophora and Cnidaria were used as the outgroup. Annelida, Mollusca, Entoprocta, Phoronida, Nemertea, Brachiopoda and Sipuncula (that is, all included Lophotrochozoa except Bryozoa) formed a monophyletic clade with maximum likelihood bootstrap support of 81% and Bayesian posterior probability of 0.66 when all data were analysed. The clade was also seen (but included one arthropod, the symphylan) when only genes other than 18S rRNA were analysed. Two Mollusca with long branch-lengths (Nautilus and Philippia) were removed from Lophotrochozoa in maximum parsimony analyses of all data. The Ecdysozoa (Kinorchyncha, Priapula, Nematoda, Onychophora, Tardigrada and Arthropoda) were included in a clade with Chaetognatha (maximum likelihood support of 80%, Bayesian probability of 0.57) in the total data. This clade excluding the symphylan had Bayesian probability of 0.66 when 18S r DNA data were excluded. The reciprocal separation of Annelida and Mollusca was generally supported where this could be resolved. The monophyly of Anelida was contradicted only by the inclusion of Sipuncula and Brachiopoda and the exclusion of Owenia. Molluscan monophyly was contradicted by the anomalous placement of Nautilus and/or Philippia but these taxa were never placed in Annelida.

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