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Early-branching or fast-evolving eukaryotes? An answer based on slowly evolving positions
H Philippe1, P Lopez, H Brinkmann
1Phylogénie et Evolution Moléculaires (UPRES-A 8080), Université Paris-Sud, Orsay, France. herve.philippe@bc4.u-psud.fr
Proceedings. Biological Sciences
|July 21, 2000
Summary
Eukaryotic evolution models based on ribosomal RNA are challenged by new analysis. Fast-evolving lineages were previously misidentified, suggesting a rapid diversification of eukaryotes rather than a linear progression.
Area of Science:
- Evolutionary Biology
- Molecular Phylogenetics
- Genomics
Background:
- Current eukaryotic evolution models rely heavily on ribosomal RNA sequence comparisons.
- These models suggest early-emerging, amitochondriate lineages represent stages in eukaryotic cell assembly.
Purpose of the Study:
- To re-examine the established paradigm of eukaryotic evolution.
- To investigate phylogenetic incongruences arising from molecular data.
Main Methods:
- Application of a novel slow-fast method analyzing nucleotide substitution rates.
- Comparative analysis of different molecular markers to assess phylogenetic stability.
Main Results:
- Early-emerging lineages identified in ribosomal RNA trees are fast-evolving and subject to long branch attraction artefacts.
- Phylogenetic incongruences are explained by the misplacement of fast-evolving groups.
- Eukaryotic phylogeny is better represented by a multifurcation, indicating rapid diversification.
Conclusions:
- The current paradigm of eukaryotic evolution requires significant revision.
- The rapid diversification of extant eukaryotic lineages is supported, potentially by multiple cladogeneses.
- Further resolution may come from analyzing rare evolutionary events like gene fusions or shared indels.