Long branch attraction

From Freepedia

Long branch attraction is a problem that occurs in molecular phylogeny, where rapidly evolving groups tend to cluster near the base of calculated evolutionary trees. This is very common when the evolution of a gene has not been clock-like. For instance, the Microsporidia are extremely simplified, and their rRNA genes have undergone considerable change. Thus rRNA trees show them to be a very primitive group, but other genes show them to be derived from fungi. Because of this, calculated trees must be interpreted with caution.

References

• David Moreira, Hervé Philippe (2000). Molecular phylogeny: pitfalls and progress. International Microbiology 3:9-16