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Published on: May 13, 2019
Class-level relationships in the phylum Cnidaria: molecular and morphological evidence
D Bridge1, C W Cunningham, R DeSalle
1Department of Invertebrates, American Museum of Natural History, New York, New York 10024, USA.
Molecular Biology and Evolution
|July 1, 1995
Summary
Cnidarian evolutionary history remains debated. This study uses DNA and morphology to group cnidarian classes, revealing Anthozoa as basal and medusa-possessing classes as a distinct group.
Area of Science:
- Zoology
- Evolutionary Biology
- Phylogenetics
Background:
- The evolutionary history of cnidarian life cycles has been a long-standing debate since the 1880s.
- Disagreement persists due to limited examination of cnidarian class relationships using modern systematic methods.
Purpose of the Study:
- To investigate the systematic relationships among the four cnidarian classes.
- To resolve the evolutionary history of cnidarian life cycles and class interrelationships.
Main Methods:
- Analysis of 18S ribosomal DNA (rDNA) sequences.
- Analysis of mitochondrial 16S rDNA sequences.
- Analysis of mitochondrial genome structure and morphological characters.
- DNA sequences were aligned using a repeatable parsimony-based approach with varied alignment parameters.
Main Results:
- All data sets, individually and combined, consistently group cnidarian classes that possess a medusa stage.
- The holobenthic Anthozoa class is consistently resolved as basal within the phylum.
- Phylogenetic analyses support a monophyletic group of medusa-bearing cnidarians.
Conclusions:
- The study provides a robust phylogenetic framework for cnidarian evolution.
- The findings clarify the relationships between cnidarian classes, resolving long-standing debates.
- The results indicate that the ancestral cnidarian likely possessed a medusa stage.
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