Understanding the Difference Between a Phylogenetic and a Cladistical Tree of Life.
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.
One of the main differences between phylogenetic trees and cladistical classification systems is that phylogenetic trees are based on the comparative analysis of different characters, while cladistical classification systems are based on the identification of the most likely branching pattern. This means that phylogenetic trees are more flexible in terms of the characters that can be used to infer evolutionary relationships, while cladistical classification systems are more constrained by the available data. Additionally, phylogenetic trees can be used to infer the relative ages of the different lineages of organisms, while cladistical classification systems cannot. This means that phylogenetic trees are more focused on understanding the evolutionary history of a group of organisms, while cladistical classification systems are more focused on organizing organisms into groups based on their evolutionary relationships.
Yet, another point of consideration is that cladistical classification systems do not provide information about the evolutionary processes that led to the divergence of different lineages, while phylogenetic trees can provide some insight into the evolutionary processes that led to the divergence of different lineages.
So, what is an educator to do? Which model is correct, and which one should you use? It is safe to say that both models have their strengths and drawbacks. There is no 500 lb. gorilla in the Montessori classroom, and it would be wrong to claim that one system is better than the other. Before you move your five or six kingdom charts and materials to the history shelf, take a moment and consider how they fit with the model you are working with. What are the expectations of your district, your parents, and understand how those fit in with the scientific community. Can you use the kingdom classification system with the tree of life? Which tree should you follow? Is it safe to present both models? The answer might surprise you. We will be taking a closer look at both models in future articles as well as examining other concepts and ideas which may be confusing to many of us.