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Phylogeny of benthic Phyllodocidae (Polychaeta) based on morphological and molecular data
Jenny Eklöf1, Fredrik Pleijel, Per Sundberg
1Department of Zoology, University of Göteborg, P.O. Box 463, SE-405 30 Göteborg, Sweden. jenny.eklof@zool.gu.se
Molecular Phylogenetics and Evolution
|June 15, 2007
Summary
This study reveals that traditional morphological characters for classifying benthic polychaetes (segmented worms) are unreliable. Molecular and morphological analyses show current subfamilies and genera are not natural evolutionary groups, necessitating taxonomic revision.
Area of Science:
- Marine Biology
- Systematic Zoology
- Molecular Phylogenetics
Background:
- Phyllodocidae, a family of marine polychaetes, has traditionally been classified using morphological characteristics.
- Previous classifications may not accurately reflect evolutionary relationships due to potential homoplasy in morphological traits.
Purpose of the Study:
- To conduct the first combined molecular and morphological analysis of benthic phyllodocids.
- To reassess the monophyly of existing phyllodocid subfamilies and genera.
- To clarify evolutionary relationships within the Phyllodocidae family.
Main Methods:
- Phylogenetic analyses using parsimony, maximum likelihood, and Bayesian inference.
- Incorporation of molecular data (18S rDNA, 28S rDNA, 16S rDNA, COI) and morphological characters.
- Assessment of 19 phyllodocid species and 2 outgroup taxa.
Main Results:
- High levels of homoplasy were observed in traditional morphological characters.
- All three current subfamilies (Phyllodocinae, Eteoninae, Notophyllinae) were found to be non-monophyletic.
- Several genera, including Eulalia, were identified as non-monophyletic, requiring taxonomic revision.
- Specific clades were well-supported, such as Eulalia, Eumida, Protomystides, Pseudomystides, Pterocirrus, and Sige forming a group, and Mystides and Nereiphylla forming another.
- Eteone and Paranaitis formed a strongly supported clade, with Eteone nested within a paraphyletic Paranaitis, suggesting segment fusion in Eteone.
- The ancestral state of median antenna/nuchal papilla and parapodia type remains ambiguous.
- Absence of cirri on segment 3 was found to be highly homoplastic.
Conclusions:
- Traditional morphological characters used for phyllodocid classification exhibit significant homoplasy and are unreliable.
- Current subfamilial and generic classifications within Phyllodocidae are not supported by evolutionary data.
- Taxonomic revision of the Phyllodocidae family is necessary, particularly for genera like Eulalia.
- Molecular data combined with morphology provide a more robust framework for understanding phyllodocid evolution.
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