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Birds in a bush: five genes indicate explosive evolution of avian orders
1Department of Biology, Museum of Southwestern Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA. anolis@unm.edu
Evolution; International Journal of Organic Evolution
|April 8, 2004
Summary
Recent bird evolutionary studies show poorly resolved relationships among Neoaves (modern birds), suggesting rapid, simultaneous radiation. This explosive radiation explains the difficulty in establishing a definitive bird phylogeny.
Area of Science:
- Evolutionary Biology
- Phylogenetics
- Ornithology
Background:
- Recent phylogenetic studies of Neoaves (most modern birds) yield poorly resolved relationships, indicating a potential explosive evolutionary radiation.
- Simultaneous radiations are evolutionarily rare and difficult to confirm, as poor phylogenetic resolution can stem from analytical artifacts.
Purpose of the Study:
- To test the explosive radiation hypothesis for Neoaves using five independent genetic datasets.
- To develop and apply novel statistical methods for detecting simultaneous evolutionary radiations (polytomies).
Main Methods:
- Proposed a methodology for testing evolutionary lineage polytomies.
- Conducted likelihood-ratio tests comparing resolved and zero-length branch phylogenetic trees.
- Analyzed topological congruence across independent gene trees and employed a power test for the SOWH test.
Main Results:
- Evidence of extremely short, sometimes zero-length, branches for interordinal Neoaves relationships across independent gene trees.
- Significant topological incongruence observed among independent gene trees.
Conclusions:
- The findings support an explosive radiation event in bird evolution, with multiple Neoaves lineages diversifying simultaneously.
- This simultaneous radiation explains the persistent challenges in resolving a robust avian phylogeny despite extensive research.