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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 Klemm1 — 1Bioinformatics 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).