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Novel Sequence Discovery by Subtractive Genomics
Published on: January 25, 2019
Phylogenetic relationships in Gleditsia (Leguminosae) based on ITS sequences
Andrew Schnabel1, Patrick E McDonel, Jonathan F Wendel
1Department of Biological Sciences, Indiana University South Bend, South Bend, Indiana 46634 USA;
American Journal of Botany
|June 11, 2011
Summary
Phylogenetic analysis of Gleditsia and Gymnocladus using nuclear ribosomal DNA (ITS) and chloroplast DNA (cpDNA) suggests an East Asian origin. Dispersal across the Bering land bridge led to North American diversification, with some species showing recent evolutionary splits.
Area of Science:
- Evolutionary Biology
- Phylogenetics
- Biogeography
- Molecular Systematics
Background:
- Gleditsia (honey locust) and its sister genus Gymnocladus are important components of legume ecosystems.
- Understanding their evolutionary history and geographic distribution is crucial for conservation and ecological studies.
- Previous hypotheses on their origin and dispersal remain debated.
Purpose of the Study:
- To test competing phylogenetic and biogeographic hypotheses for the genus Gleditsia.
- To infer the origin and diversification patterns of Gleditsia and Gymnocladus.
- To investigate the evolutionary relationships between Asian and North American species.
Main Methods:
- Analysis of nucleotide sequences from the internal transcribed spacers (ITS) and 5.8S gene of nuclear ribosomal DNA.
- Combined data set including ITS and two chloroplast genes (cpDNA).
- Phylogenetic analyses to reconstruct evolutionary relationships and biogeographic history.
Main Results:
- Gleditsia and Gymnocladus originated in East Asia during the Eocene epoch.
- Eastern North American species likely evolved from ancestors migrating across the Bering land bridge.
- Gleditsia amorphoides represents an early divergence, suggesting long-distance dispersal from Asia; remaining Gleditsia species form three unresolved clades, with North American species being polymorphic and paraphyletic, indicating recent diversification.
Conclusions:
- The study supports an East Asian origin for Gleditsia and Gymnocladus, with subsequent dispersal to North America.
- The timing of the East Asian/North American disjunction differs between the two genera.
- Recent diversification is suggested for North American Gleditsia species, highlighting complex evolutionary dynamics.
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