The tree represents one possible genealogy generating the data of Table1. The seven samples with integer genotype pairs at x and y are attached to the leaves of the genealogical tree. Initial genotype pair at the root is assumed as 00, wildtype at x and wildtype at y. The left line represents the time from the earliest mutation event of the sample (as “init”) to the current sample (as “present”). The seven time intervals are illustrated in the context of coalescent tree of the seven samples. From the leaves to the root, the six coalescent events determine the time intervals, T1,…,T7. Two mutations at x and y occurred in time interval T5 and T2, respectively which are marked as circles with “x” and “y”.