( parsimony) The selection of the phylogenetic tree requiring the least number of substitutions from among all possible phylogenetic trees as the most likely to be the true phylogenetic tree.
A criterion for estimating a parameter from observed data based on the principle of minimising the number of events needed to explain the data. In phylogenetic analysis, the optimal tree under the maximum parsimony criterion is the tree that requires the fewest number of character-state changes.
The principle of simpler solutions being preferred over more complex ones. In relation to phylogeny reconstruction this means that phylogenetic trees that can explain a datamatrix by fewer evolutionary events is preferable over a tree that requires more evolutionary events.