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Evolutionary processes in the genus Coreocarpus: insights from molecular phylogenetics.
Rebecca T Kimball1, Daniel J Crawford, Edwin B Smith
1Department of Zoology, University of Florida, PO Box 118525, Gainesville, Florida 32611, USA. rkimball@zoo.ufl.edu
Evolution; International Journal of Organic Evolution
|March 20, 2003
Summary
Molecular phylogenetics of the plant genus Coreocarpus reveals a core group of six species. Despite strong molecular evidence, defining morphological characters remain elusive, suggesting a complex evolutionary history.
Area of Science:
- Botany
- Molecular Biology
- Evolutionary Biology
Background:
- The plant genus Coreocarpus has been subject to biosystematic studies, but its evolutionary relationships and species delimitations require further investigation.
- Previous research indicated well-defined species within Coreocarpus, with no evidence of past hybridization.
Purpose of the Study:
- To conduct a molecular phylogenetic study of the plant genus Coreocarpus using nuclear and plastid DNA sequences.
- To clarify the evolutionary relationships and species delimitations within the genus Coreocarpus.
- To compare molecular findings with existing biosystematic and morphological data.
Main Methods:
- Utilized nuclear (ITS) and plastid (rpl16 intron) DNA sequences for phylogenetic analysis.
- Constructed phylogenies based on both nuclear and plastid DNA datasets.
- Mapped results of previous breeding studies onto the molecular phylogeny.
Main Results:
- Highly congruent phylogenies from nuclear and plastid sequences identified a monophyletic core group of six Coreocarpus species, excluding three previously included species.
- Relationships within the core group largely align with, but are not entirely concordant with, prior biosystematic studies.
- No consistent morphological characters were identified for the core Coreocarpus group, potentially due to retained ancestral traits and genetic lability.
- Estimated the age of the core Coreocarpus group at approximately 1 million years.
- Observed three instances of incongruence: two between nuclear and plastid data, and one between morphological assignment and molecular data.
- Cross-compatibility data suggests that if hybridization occurred, it was between now cross-incompatible and allopatric species.
Conclusions:
- The molecular data strongly supports a distinct core group within Coreocarpus, necessitating a re-evaluation of its taxonomy.
- The lack of unifying morphological characters suggests complex evolutionary processes, including potential parallel character evolution.
- The evolutionary history of Coreocarpus is more intricate than previously understood, highlighting the complementary roles of molecular and biosystematic approaches in phylogenetic research.