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Polyphyletism of Celastrales deduced from a chloroplast noncoding DNA region
V Savolainen1, R Spichiger, J F Manen
1Laboratoire de Botanique Systématique et Floristique, Conservatoire et Jardin Botaniques de la Ville de Genève, Switzerland.
Molecular Phylogenetics and Evolution
|April 1, 1997
Summary
The order Celastrales is polyphyletic, with only Celastraceae belonging to it. Other families previously included are now placed in Asteridae or unrelated to Celastrales based on DNA analysis.
Area of Science:
- Plant Systematics
- Molecular Phylogenetics
- Angiosperm Taxonomy
Background:
- Previous studies investigated Celastrales phylogeny using chloroplast rbcL 5' flanking sequences.
- The order Celastrales, as defined by Cronquist, comprises seven families.
Purpose of the Study:
- To re-evaluate the phylogenetic position of the order Celastrales.
- To determine the relationships of families and genera previously associated with Celastrales using molecular data.
Main Methods:
- Cladistic analysis of chloroplast rbcL 5' flanking DNA sequences.
- Inclusion of additional dicot species from Celastrales families and related genera.
Main Results:
- The order Celastrales is polyphyletic, redefined to include only Celastraceae (with Hippocrateaceae and Brexia) and Parnassia as its sister.
- Aquifoliaceae and Helwingia are placed within Asteridae.
- Salvadoraceae, Geissolomataceae, Icacinaceae, Phellinaceae, Aextoxicaceae, Corynocarpaceae, Dichapetalaceae, Stackhousiaceae, and Goupiaceae are not related to Celastrales.
Conclusions:
- The chloroplast rbcL 5' flanking region is a useful marker for angiosperm phylogeny.
- The study clarifies the taxonomic நிலை of several families, revising the circumscription of Celastrales.
- Observed influence of A+T content on transversions in noncoding chloroplast DNA.