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 Hervé Philippe

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Talk Title :
Phylogenomics of animals

Date / Time / Location:
Thursday March 12th, 2009 – 6:00 pm
Room 232, Leacock Building
McGill University
855 Sherbrooke Street West

Affiliation :
Centre Robert-Cedergren

URL
Hervé Philippe

Abstract :
The metazoan phylogeny has undergone major rearrangements at the end of the nineties. However, the resolution was rather poor, preventing to draw any firm conclusions. Phylogenomics, with the availability of large sets of sequences, is usually expected to increase the resolving power of molecular phylogenetic inference, leading potentially to fully resolved tree. Unfortunately, numerous phylogenomic trees of animals have been recently published and not only resolution is often poor and but also results are regularly contradictory. I will explore the reasons of these apparently deceiving results:

  1. Inadequate selection of sequences (non-orthologous sequences, saturated genes).
  2. Inadequate taxon sampling.
  3. Inadequate tree reconstruction method. When more and more data are considered, although stochastic error vanishes, systematic error becomes more apparent. Such errors are due to the imperfection of models of sequence evolution.
  4. Rapid diversification of animal phyla (Cambrian explosion). Lack of resolution is generally interpreted as evidence of closely spaced speciation events. Molecular dating may allow to test this hypothesis.

In conclusion, I will present my view on the phylogenetic relationships of animals.