This is less easy to look at. The program should work successfully on DEC VAX systems under either the VMS or the Unix operating systems without any other changes. The program defaults to carrying out Dollo parsimony. The method is named after Louis Dollo since he was one of the first to assert that in evolution it is harder to gain a complex feature than to lose it. The characters are evolving independently.
Different lineages evolve independently.
The lengths of the segments of the true tree are not so unequal that two changes in a long segment are as probable as one in a short segment. One problem can arise when using additive binary recoding to represent a multistate character as a series of two-state characters. Unlike the Camin- Sokal, Wagner, and Polymorphism methods, the Dollo method can reconstruct ancestral states which do not exist. The program tries to minimize the total number of polymorphic characters, where each polymorphism is counted once for each segment of the tree in which it is retained. The characters are evolving independently of each other.