A few articles have been authored in the Montessori community regarding the types of classifications we should use in our Montessori classrooms. Yet, few of us can understand the difference between the various classification systems and we run around wondering if we need to stop what we are doing and follow the advice provided by the most recent article. In this article we will be looking at the difference between the Phylogenetic and the Cladistics classification system. Phylogenetic trees and cladistical classification systems are both methods used to infer evolutionary relationships among organisms, but they differ in several ways.
To begin with, a phylogenetic tree is a diagram that represents the evolutionary relationships among a group of organisms. It is constructed based on the principle of common descent, which states that all organisms share a common ancestor. The tree is composed of branches that represent the different lineages of organisms, and the branching points (nodes) represent the points in evolutionary history where new lineages have diverged. The branches of the tree are labeled with the names of the organisms or groups of organisms that they represent, and traditionally, the length of the branches is used to indicate the amount of evolutionary change that has occurred. Phylogenetic trees are based on the comparative analysis of different characters (such as DNA sequences, morphology, etc.) that are believed to be informative about evolutionary relationships.
A cladistical classification system, on the other hand, is a method of organizing organisms into groups based on their evolutionary relationships. It is based on the principle of parsimony, which states that the most likely explanation for the similarities and differences among organisms is that they are inherited from a common ancestor. Cladistical classification systems are constructed by identifying the most likely branching pattern (cladogram) that represents the evolutionary relationships among a group of organisms. The cladogram is then used to assign organisms to groups (clades) that are defined by the branching points (nodes) of the cladogram. Clades are named based on the characteristics of the organisms that they contain and are arranged in a hierarchical structure that reflects the degree of evolutionary relatedness.
Aki Margaritis is the Executive Director of ETC Montessori and holds teaching credentials for middle school and high school with advanced degrees in the areas of biology, math, and chemistry. He also holds a Montessori Secondary I credential from AMS.