Investigation of molluscan phylogeny on the basis of 18S rRNA sequences

The 18S rRNA sequences of 12 molluscs, representing the extant classes Gastropoda, Bivalvia, Polyplacophora, Scaphopoda, and Caudofoveata, were determined and compared with selected known 18S rRNA sequences of Metazoa, including other Mollusca. These data do not provide support for a close relations...

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Bibliographic Details
Published in:Molecular biology and evolution 1996-12, Vol.13 (10), p.1306-1317
Main Authors: Winnepenninckx, B, Backeljau, T, De Wachter, R
Format: Article
Language:English
Subjects:
Animals
Bivalvia
Brackish
Caudofoveata
Freshwater
Gastropoda
Marine
Metazoa
Molecular Sequence Data
Mollusca
Mollusca - genetics
Phylogeny
Polyplacophora
RNA, Ribosomal, 18S - genetics
Scaphopoda
Sequence Analysis, DNA
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Summary:The 18S rRNA sequences of 12 molluscs, representing the extant classes Gastropoda, Bivalvia, Polyplacophora, Scaphopoda, and Caudofoveata, were determined and compared with selected known 18S rRNA sequences of Metazoa, including other Mollusca. These data do not provide support for a close relationship between Platyhelminthes (Turbellaria) and Mollusca, but rather suggest that the latter group belongs to a clade of eutrochozoan coelomates. The 18S rRNA data fail to recover molluscan, bivalve, or gastropod monophyly. However, the branching pattern of the eutrochozoan phyla and classes is unstable, probably due to the explosive Cambrian radiation during which these groups arose. Similarly, the 18S rRNA data do not provide a reliable signal for the molluscan interclass relationships. Nevertheless, we obtained strong preliminary support for phylogenetic inferences at more restricted taxonomic levels, such as the monophyly of Polyplacophora, Caenogastropoda, Euthyneura, Heterodonta, and Arcoida.
ISSN:0737-4038
1537-1719
DOI:10.1093/oxfordjournals.molbev.a025577