Branching Random Walks on Binary Strings for Evolutionary Processes
  In this article, we study branching random walks on graphs modeling division-mutation processes inspired by adaptive immunity. We apply the theory of expander graphs on mutation rules in evolutionary processes and obtain estimates for the cover times of the branching random walks. This analysis reveals an unexpected saturation phenomenon : increasing the mutation rate above a certain threshold does not enhance the speed of state-space exploration. 
Irene Balelli, Vuk Milisic, Gilles Wainrib
math.PR