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A phylogenetic analysis of Rhamnaceae using rbcL and trnL-F plastid DNA sequences
J E Richardson1, M F Fay, Q C Cronk
1Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, UK;
American Journal of Botany
|September 19, 2000
Summary
This study uses DNA sequencing to reclassify the Rhamnaceae family, revealing new tribal classifications based on molecular data. These findings support the family's monophyly and suggest new groupings within the Rhamnaceae.
Area of Science:
- Plant Systematics
- Molecular Phylogenetics
- Evolutionary Biology
Background:
- Previous tribal classifications of Rhamnaceae relied on fruit morphology, leading to broad, heterogeneous groups.
- A comprehensive molecular analysis was needed to refine the understanding of Rhamnaceae relationships.
Purpose of the Study:
- To evaluate the existing tribal classification of Rhamnaceae using molecular data.
- To establish a new, more accurate tribal classification for Rhamnaceae based on phylogenetic analysis.
- To investigate the phylogenetic position of Rhamnaceae relative to related families.
Main Methods:
- DNA sequencing of two plastid genome regions (rbcL and trnL-F) from 42 Rhamnaceae genera.
- Phylogenetic analyses using maximum likelihood and parsimony methods.
- Comparison of phylogenetic signal and patterns of change between rbcL and trnL-F datasets.
Main Results:
- Phylogenetic trees from plastid DNA support the monophyly of the Rhamnaceae family.
- Dirachmaceae and Barbeyaceae are identified as the closest relatives of Rhamnaceae, followed by urticalean families.
- Three strongly supported clades within Rhamnaceae were identified, though distinct morphological characters for formal subfamilial classification were not found.
Conclusions:
- The molecular data provide a robust basis for a new tribal classification of Rhamnaceae.
- While molecular data reveal distinct clades, formal taxonomic recognition is limited to groups with supporting morphological characters.
- The study offers insights into the biogeography of Rhamnaceae informed by molecular phylogenies.