  This is an introductory review of deterministic mutation-selection models for
asexual populations (i.e., quasispecies theory) and related topics. First, the
basic concepts of fitness, mutations, and sequence space are introduced.
Different types of mutation-selection dynamics are defined and their relation
to problems of statistical physics are outlined. Then the stationary population
distribution in simple, single peak fitness landscapes is discussed at length,
with particular emphasis on the error threshold phenomenon. Extensions of the
theory covering e.g. epistatic interactions, diploid organisms,
semiconservative replication and time-dependent fitness peaks are briefly
described. A further section is devoted to randomly rugged fitness landscapes,
which may display fitness correlations of various degree as well as extended
neutral networks. The final two sections address evolutionary dynamics in both
rugged and smooth fitness landscapes, and provide a brief overview of pertinent
experiments.
