Dresden 2011 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 35: SYBE: Statistical Physics and Biological Evolution

BP 35.4: Hauptvortrag

Freitag, 18. März 2011, 12:00–12:30, TRE Ma

The role of horizontal gene transfer in the evolution of bacterial genomes — •Paul Higgs — McMaster University, Hamilton, Ontario, Canada

For a set of related genomes, the core is the set of genes found in every genome, and the pan-genome is the set found in at least one genome. The pan-genome is usually much larger than the core. Genes can be lost by deletion and they can be gained by duplication, by de novo evolution of a new sequence, or by horizontal gene transfer (HGT) from another organism. We analyze clusters of related genes from a large number of complete genomes in order to estimate the relative rates of these processes. If the rate of HGT is very high, the traditional tree-like picture of evolution breaks down. It has been argued that the HGT rate was so high in the earliest cells that there were no separate lineages of organisms. Only when the HGT rate began to fall would lineages begin to emerge with their own distinct sets of genes. This phenomenon has been called the Darwinian Threshold. We study a model for genome evolution that incorporates both beneficial and detrimental effects of HGT and show that the model predicts the occurrence of a Darwinian Threshold.