Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 21: Population Dynamics and Evolution

BP 21.4: Talk

Thursday, March 26, 2009, 18:15–18:30, HÜL 186

The pace of evolution across fitness valleys — •Chaitanya Gokhale and Arne Traulsen — Max-Planck-Institute for Evolutionary Biology, 24306 Plön, Germany

How fast does a population evolve from one fitness peak to another? We study the dynamics of evolving, asexually reproducing populations in which a certain number of mutations jointly confer a fitness advantage. We consider the time until a population has evolved from one fitness peak to another one with a higher fitness. The order of mutations can either be fixed or random. If the order of mutations is fixed, then the population follows a metaphorical ridge, a single path. If the order of mutations is arbitrary, then there are many ways to evolve to the higher fitness state. In this case, evolution proceeds on a hypercube in d dimensions, where d is the number of required mutations. We address the time required for fixation in such scenarios via analytical expressions for small mutation rates and approximations based on differential equations for higher mutation rates. We also study how the time is affected by the order of mutations, the population size and the fitness values. We also compare a single path, in which the intermediate states have the same fitness values as the initial state, to a hypercube with a fitness valley and ask whether it is faster to cross the fitness landscape via a ridge or a broad fitness valley.