What is the Difference Between Dendrogram and Cladogram

The main difference between dendrogram and cladogram is that a dendrogram represents hierarchical relationships and clustering patterns among objects or entities, while a cladogram represents evolutionary relationships and common ancestry among groups of organisms.

Dendrograms and cladograms are graphical representations that depict relationships but serve different purposes. While a dendrogram focuses on illustrating hierarchical relationships and clustering patterns among objects or entities, a cladogram is specifically designed to display the evolutionary relationships and shared ancestry among groups of organisms.

Key Areas Covered

1. What is a Dendrogram  
     – Definition, Features, Purpose
2. What is a Cladogram
     – Definition, Features, Purpose
3. Similarities Between Dendrogram and Cladogram
     – Outline of Common Features
4. Difference Between Dendrogram and Cladogram
     – Comparison of Key Differences

Key Terms

Dendrogram, Cladogram

What is a Dendrogram

A dendrogram is a diagram or a tree-like structure showing hierarchical relationships between different objects or entities. It is commonly used in various fields, such as biology, data analysis, and taxonomy. In a dendrogram, objects or entities are represented as individual points or clusters, and the distance or similarity between them is measured and displayed through the lengths and connections of branches.

Figure 1: Euclidean Distance Dendrogram 

Dendrograms are particularly useful for visualizing and understanding the grouping or clustering of data. They can reveal patterns of similarity or dissimilarity among the objects being compared. The arrangement of the branches and clusters in a dendrogram provides insights into the relationships and hierarchical structure within the data. Dendrograms can be created using various methods, such as hierarchical clustering algorithms, and they are an effective tool for exploring and interpreting complex relationships and classifications.

What is a Cladogram

A cladogram is a visual representation that illustrates the hypothetical relationships between different groups of organisms and their shared ancestors. The term “cladogram” originates from the Greek words clados, meaning “branch,” and gramma, meaning “character.” Cladograms may look like the branches of a tree, expanding outward from a central point. In a cladogram, the root is like the main trunk, representing the ancestor from which all the other groups come. The cladogram uses lines that branch out and end in a group of organisms called a clade. These organisms share a hypothetical common ancestor. The places where the lines meet are called nodes, representing the common ancestors.

Figure 2: Cladogram of Former “Reptilia”

Cladograms are not necessarily vertical. They can have various orientations, including vertical, horizontal, or diagonal branching patterns. They can range from simplistic representations, comparing only a few organism groups, to intricate structures that aim to classify all living forms. However, cladograms are commonly used to classify animals more than other organisms.

Scientists use synapomorphies, which are shared characteristics that are inherited, to compare different groups and create cladograms. Examples of synapomorphies include traits like having fur and laying shelled eggs. In the past, synapomorphies were identified based on observable physical traits, but nowadays, DNA and RNA sequencing data and proteins are used in modern cladograms. Moreover, scientists use the term cladistics to refer to the process of hypothesizing relationships between organisms and constructing cladograms. The hypothetical relationships are called phylogeny, representing the evolutionary connections between organisms. Phylogenetics is the field that studies the evolutionary history and relationships between organisms or groups.

Similarities Between Dendrogram and Cladogram

• Both dendrograms and cladograms are graphical representations that visualize relationships or patterns.
• These diagrams feature a branching structure representing connections and relationships between entities or groups.
• Both dendrograms and cladograms exhibit a hierarchical organization, showcasing the relationships hierarchically.

Difference Between Dendrogram and Cladogram

Definition

A dendrogram is a diagram or a tree-like structure showing hierarchical relationships between different objects or entities. At the same time, a cladogram is a visual representation that illustrates the hypothetical relationships between different groups of organisms and their shared ancestors.

Purpose              

While a dendrogram represents hierarchical relationships and clustering patterns among objects or entities, a cladogram represents evolutionary relationships and shared ancestry among groups of organisms.

Focus

Dendrograms emphasize hierarchical relationships and clustering patterns in the data, whereas cladograms focus on genetic or morphological similarities and differences.

Field

Dendrograms are used in various fields, such as data analysis, biology, and taxonomy, whereas cladograms are used explicitly in the field of biology and taxonomy.

Conclusion

The main difference between dendrogram and cladogram is that a dendrogram represents hierarchical relationships and clustering patterns among objects or entities, while a cladogram represents evolutionary relationships and common ancestry among groups of organisms. Therefore, dendrograms focus on hierarchical relationships and clustering patterns in the data, whereas cladograms focus on genetic or morphological similarities and differences.

Reference:

1. Bock, Tim.“What is a Dendrogram?” Displayr.
2. Helmenstine, Anne Marie. “What Is a Cladogram? Definition and Examples.” ThoughtCo.

Image Courtesy:

1. “Egypt Dendrogram”  By Nabaten – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Cladogram Amniota A” By Amélie Pataud – Own work (CC BY-SA 4.0) via Commons Wikimedia