In a cladogram (a type of phylogenetic tree), clades are groups of related organisms. In the past, phylogenetic lists built clades using the idea of parsimony, that the pattern that uses the fewest evolutionary changes is the most likely to be correct. Today, with the use of computers and DNA sequences, the explanation that is thought to be the best is .

one with the fewest number of genetic differences in the nucleotide sequence.

Explanation:

A cladogram is a diagram capable of showing the relationships among different species and/or group of organisms. In a cladogram, the root indicates the common ancestor, while internal nodes represent the common ancestors of each group. In consequence, this diagram can be used to establish evolutionary relationships in which the start branch points represent common ancestors shared by the organisms found in the 'branches'. Nonetheless, the length of the branches in the cladogram does not represent evolutionary distances among groups. In recent years, cladograms based on DNA sequencing data have been combined with morphological data to establish evolutionary relationships among species.