Journal of Molecular Evolution

, Volume 48, Issue 1, pp 2–12 | Cite as

Evolution of ITS1 rDNA in the Digenea (Platyhelminthes: Trematoda): 3′ End Sequence Conservation and Its Phylogenetic Utility

  • J. Hinrich G.v.d.  Schulenburg
  • Ulrike  Englisch
  • J.-Wolfgang  Wägele

Abstract.

A comparison of ribosomal internal transcribed spacer 1 (ITS1) elements of digenetic trematodes (Platyhelminthes) including unidentified digeneans isolated from Cyathura carinata (Crustacea: Isopoda) revealed DNA sequence similarities at more than half of the spacer at its 3′ end. Primary sequence similarity was shown to be associated with secondary structure conservation, which suggested that similarity is due to identity by descent and not chance. Using an analysis of apomorphies, the sequence data were shown to produce a distinct phylogenetic signal. This was confirmed by the consistency of results of different tree reconstruction methods such as distance approaches, maximum parsimony, and maximum likelihood. Morphological evidence additionally supported the phylogenetic tree based on ITS1 data and the inferred phylogenetic position of the unidentified digeneans of C. carinata met the expectations from known trematode life-cycle patterns. Although ribosomal ITS1 elements are generally believed to be too variable for phylogenetic analysis above the species or genus level, the overall consistency of the results of this study strongly suggests that this is not the case in digenetic trematodes. Here, 3′ end ITS1 sequence data seem to provide a valuable tool for elucidating phylogenetic relationships of a broad range of phylogenetically distinct taxa.

Key words: Ribosomal internal transcribed spacer 1 — Secondary structure conservation — Phylogenetic analysis — Analysis of apomorphies — Digenea —Cyathura carinata— Isopoda 

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Copyright information

© Springer-Verlag New York Inc. 1999

Authors and Affiliations

  • J. Hinrich G.v.d.  Schulenburg
    • 1
  • Ulrike  Englisch
    • 1
  • J.-Wolfgang  Wägele
    • 1
  1. 1.Abteilung für Systematik und Morphologie der Tiere, Fakultät für Biologie, Universität Bielefeld, 33501 Bielefeld, GermanyDE

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