Dresden 2009 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 2: Statistical physics in biological systems I (joint session DY/BP)

DY 2.7: Talk

Monday, March 23, 2009, 12:30–12:45, ZEU 255

Selectively accessible paths in fitness landscapes — •Jasper Franke and Joachim Krug — Institut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany

A mutation of an organism’s genome changing one nucleotide in the DNA has a higher probability of becoming fixed in the population if it increases the mutant’s degree of adaptation to the environment (it’s ‘fitness’). A sequence of mutations that each increase the fitness of the respective mutant therefore forms a selectively accessible trajectory in the (generally very high-dimensional) space of sequences. This concept of accessible paths plays an important role in determining the possible configurations that can be reached starting from a given position in the sequence space.

Since the mapping from genotype to fitness is rather intricate and only partially understood, the fitness landscape can be modelled as a random landscape with a certain amount of correlation between the fitness values of different genotypes. The NK- Modell introduced by Kauffman was used to generate this family of fitness landscapes with tunable degree of correlation and thus tunable ruggedness.

In this talk, we present numerical results on the statistics of the selectively accessible paths in these fitness landscapes depending on the ruggedness.