Exact solution of a model of time-dependent evolutionary dynamics in a   rugged fitness landscape
  A simplified form of the time dependent evolutionary dynamics of a quasispecies model with a rugged fitness landscape is solved via a mapping onto a random flux model whose asymptotic behavior can be described in terms of a random walk. The statistics of the number of changes of the dominant genotype from a finite set of genotypes are exactly obtained confirming existing conjectures based on numerics. 
Clement Sire, Satya N. Majumdar and David S. Dean