Griffiths-Pakes branching process with infinite-allele mutations. A non-mutant clone of particles is evolving in time according to a single-type branching process (in our case, time dicrete). With probability μ per time step, a particle mutates and initates a clone of new previously nonexistent type, which evolves according to the same rules as the original non-mutant clone. As a result, a set of clones of different types emerges, spawning further clones, some of which may die out. Upper panel: low μ; lower panel: high μ.
Kimmel and Mathaes BMC Genomics 2010 11(Suppl 1):S11 doi:10.1186/1471-2164-11-S1-S11