%0 Journal Article
%T Stochastic slowdown in evolutionary processes
%A Philipp M. Altrock
%A Chaytanya S. Gokhale
%A Arne Traulsen
%J Quantitative Biology
%D 2010
%I arXiv
%R 10.1103/PhysRevE.82.011925
%X We examine birth--death processes with state dependent transition probabilities and at least one absorbing boundary. In evolution, this describes selection acting on two different types in a finite population where reproductive events occur successively. If the two types have equal fitness the system performs a random walk. If one type has a fitness advantage it is favored by selection, which introduces a bias (asymmetry) in the transition probabilities. How long does it take until advantageous mutants have invaded and taken over? Surprisingly, we find that the average time of such a process can increase, even if the mutant type always has a fitness advantage. We discuss this finding for the Moran process and develop a simplified model which allows a more intuitive understanding. We show that this effect can occur for weak but non--vanishing bias (selection) in the state dependent transition rates and infer the scaling with system size. We also address the Wright-Fisher model commonly used in population genetics, which shows that this stochastic slowdown is not restricted to birth-death processes.
%U http://arxiv.org/abs/1007.1340v2