The key difference between cladogram and dichotomous key is that cladogram is used to study the phylogenetic relationships among a group of organisms while a dichotomous key is used to classify and identify new species.
Classification is an important field in identifying and distinguishing organisms. Scientists discover new species through their experiments. Hence, it is necessary to identify a new species based on their characteristics and phylogeny. They use different methods. Cladogram and dichotomous keys are two types of tools that can be used to identify organisms. A cladogram shows the relationship between different organisms with respect to a common ancestor. In contrast, a dichotomous key has a series of statements consisting of two choices that describe characteristics of an unidentified organism. It is a step by step key which leads to the correct identification of an unknown organism.
CONTENTS
1. Overview and Key Difference
2. What is a Cladogram
3. What is a Dichotomous Key
4. Similarities Between Cladogram and Dichotomous Key
5. Side by Side Comparison – Cladogram vs Dichotomous Key in Tabular Form
6. Summary
What is a Cladogram?
A cladogram is a diagrammatic representation which shows the relationship between closely related organisms. It is a type of a phylogenetic tree. But it shows only the relationships between clades with a common ancestor. For example, a cladogram shows that humans are more loosely related to chimpanzees than gorillas, but it does not show the evolutionary time and the exact distance from the common ancestor.
Figure 01: Cladogram
Basically, a cladogram is a tree-like diagram which is drawn using lines. The nodes of a cladogram represent the splitting of two groups from a common ancestor. Clades are summarized at the ends of the lines, and the members of a particular clade share similar characteristics. They are built using molecular differences than morphological characteristics. However, cladograms can be constructed using the correct morphological and behavioral data as well. Cladograms are really important for biologists to organize the organisms according to what the organisms share and not share.
What is a Dichotomous Key?
A dichotomous key is a tool that helps to classify and identify an unknown organism, especially a plant or an animal. As the name “dichotomous” suggests, it consists of statements having two choices that describe characteristics of the unknown organism. Hence, the key is always divided into two parts.
Each step has two choices. The user needs to choose the best description among the two statements and move along the key until he identifies the unknown organism. When one statement is answered, the next statements can be answered. In this manner, dichotomous key identifies species by their unique scientific name. Generally, dichotomous keys are used when the two species are very similar to one another.
What are the Similarities Between Cladogram and Dichotomous Key?
- Cladogram and dichotomous key use characteristics in order to identify organisms.
- Taxonomy uses both cladogram and dichotomous keys.
- Both cladogram and dichotomous key do not reveal evolutionary relationships between organisms.
What is the Difference Between Cladogram and Dichotomous Key?
A cladogram is a diagram that shows relationships among a group of organisms based on their derived characteristics. On the other hand, a dichotomous key is a tool that helps to classify and identify an unknown organism. So, this is the key difference between cladogram and dichotomous key.
Moreover, cladogram uses derived characteristics while dichotomous key uses the characteristics that describe the unidentified organism. Furthermore, a cladogram shows how organisms are related to their common ancestor, but a dichotomous key does not show a relationship to their common ancestor.
Below infographic tabulates more comparisons related to the difference between cladogram and dichotomous key.
Summary – Cladogram vs Dichotomous Key
A cladogram is a diagram which shows the relationship of different organisms based on their derived characteristics. In contrast, a dichotomous key is a tool used to classify and identify a new organism. In fact, dichotomous keys are most often used for identifying plant and animal species based on their characteristics. Thus, this summarizes the difference between cladogram and dichotomous key.
Reference:
1. “Dichotomous Key”. Biology Dictionary, 2020, Available here.
2. “Cladogram”. En.Wikipedia.Org, 2020, Available here.
Image Courtesy:
1. “Primate cladogram” By KDS4444 – Own work (CC0) via Commons Wikimedia