Refers to a rule used to choose among possible trees, which states that the tree implying the least number of changes in character states is the best This method can be very missleading, especially if "simple" parsimony is used
One of several criteria that may be optimised in building phylogenetic trees, but a philosophically important one due to its simplicity; and the basis of the most-commonly used method of cladistic analysis, at least for morphological data The central idea of cladistic parsimony analysis is that some trees will fit the character-state data better than other trees Fit is measured by the number of evolutionary character-state changes implied by the tree The fewer changes the better, e g there is no sense in choosing a phylogeny that has roots, flowers and xylem each evolving twice, if another tree exists on which one evolutionary origin for each of the apomorphic states would explain the observed distribution of states across taxa(cf distance, maximum likelihood)
Refers to a rule used to choose among possible cladograms, which states that the cladogram implying the least number of changes in character states is the best
Brevity In GP, this is measured by counting the nodes in the tree The smaller the program, the smaller the tree, the lower the count and the more parsimonious it is