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 Wagner parsimony. Wagner parsimony allows both kinds of changes. The criterion is to find the tree which requires the minimum number of changes.
Different characters evolve independently.
Different lineages evolve independently. Both of these kinds of changes are a priori improbable over the evolutionary time spans involved in the differentiation of the group in question. Rates of evolution in different lineages are sufficiently low that two changes in a long segment of the tree are far less probable than one change in a short segment. At the beginning of the program are a series of constants, which can be changed to help adapt the program to different computer systems. Below is a test data set, but we cannot show the output it generates because of the interactive nature of the program.