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Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Posters: Statistical Physics in Biological Systems

BP 7.10: Poster

Monday, March 14, 2011, 17:15–20:00, P3

Age dependent branching in phylogenetic trees — •Stephanie Keller-Schmidt1, Murat Tugrul2,3, Victor M. Eguiluz2, Emilio Hernandez-Garcia2, and Konstantin Klemm11Bioinformatics Group, Leipzig University, Germany — 2IFISC, Palma de Mallorca, Spain — 3IST Austria, Klosterneuburg, Austria

The evolutionary diversification of biological species is a branching process reconstructed as phylogenetic trees. According to analysis of large databases (TreeBase and PANDIT), these trees have a shape (systematic imbalance) not explained by a process of uncorrelated branching events. Here we introduce the age model where the branching probability of a node (species) is inversely proportional to the time since the node was last involved in speciation. We find that the scaling of the average number of ancestors (called depth d) with total number of species n scales as d ∼ (logn)2. This result is in agreement with the scaling observed by exhaustive analysis of the databases Treebase and Pandit. Compared with a previously suggested model [1], the age model yields larger likelihood values on the trees in the databases with up to 20 leaves (where exact likelihood computation is feasible).
[1] M.G. Blum and O. François, Syst. Biol. 55, 685-691 (2006).

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