Difference Between Taxon and Clade

The key difference between taxon and clade is that taxon is a group of one or more populations of organisms seen by taxonomists to form a unit, while clade is a group of organisms that are monophyletic and is composed of a common ancestor and all its lineal descendants.

Taxon and clade are important parts of phylogenetic trees. A taxon is any group in a biological classification into which the related organisms are classified by taxonomists. A common example of a taxon is primates. A clade is a group of organisms comprised of all evolutionary decedents of a common ancestor. A good example of a clade is great apes and humans. Monophyletic groups such as clades form nested sets on a phylogenetic tree.

CONTENTS

1. Overview and Key Difference
2. What is a Taxon 
3. What is a Clade
4. Similarities Between Taxon and Clade
5. Side by Side Comparison – Taxon vs Clade in Tabular Form
6. Summary

What is a Taxon?

A taxon is a population or a group of populations of organisms that are usually phylogenetically related and which have characters in common that differentiate from other such units. A taxon can be assigned a taxonomic rank when it is given a formal name. There are seven taxonomic ranks as species, genus, family, order, class, phylum and kingdom. A group of yellow flowers, a group of aquatic animals and a group of primates are examples of several taxa.

A taxon can be monophyletic, paraphyletic or polyphyletic. Monophyletic taxon includes a group of organisms that descends from a single or common ancestor. A paraphyletic taxon is one that includes the most recent common ancestor but not all of its descendants. Polyphyletic taxon contains unrelated organisms that descend from more than one ancestor. Well-known monophyletic taxa are Mammalia and Aves (modern birds) while paraphyletic taxa consist of Pisces and Reptilia, the former including all ray-finned fish but excluding all fleshy-finned fish, and latter comprising all scaly tetrapods but excluding mammals and birds with their modified scales. Polyphyletic taxa include jawless lampreys and hagfish, various toothless, insect-eating mammals such as anteaters and armadillos.

What is a Clade?

The term “clade” was coined by the biologist Julian Huxley in 1957. A clade is a group of organisms that comprises all the evolutionary descendants of a common ancestor.  It is a group of organisms that are always monophyletic. In taxonomical literature, the Latin term cladus is often used rather than the English term (clade). The common ancestor can be an individual, a population, or a species.

Clades are nested.  A clade also contains all descendants of that branch. Clades are extremely useful in the study of biology because they can predict how different species have descended from a common ancestor and their similarities and differences. Several examples of clades are Archaebacteria, Apoikozoa, Animalia, Eukaryotes, Rosacea, Reptilomorpha and Rodentia.

The study of cladistic is the study of classifying organisms based on their relationship. The classification of organisms based on their relatedness is originated from Darwin’s theory of evolution. The recent developments in genetics allow scientists to find microscopic similarities and differences between life forms.

What are the Similarities Between Taxon and Clade?

• Both are taxonomic units.
• They are both used by taxonomists.
• Both of them are important parts of the phylogenetic tree.
• They are both group of organisms having ancestors.

What is the Difference Between Taxon and Clade?

A taxon is a rank or group in a biological classification into which taxonomists classify related organisms. A clade is a group of organisms that are monophyletic and is composed of a common ancestor and all its lineal descendants. So, this is the key difference between taxon and clade. Moreover, a taxon can be monophyletic, paraphyletic or polyphyletic. In contrast, a clade is always monophyletic. Thus, this is another important difference between taxon and clade. Furthermore, a taxon may have a single ancestor or different ancestors, while a clade always has a single common ancestor.

Below is a summary of the difference between taxon and clade in tabular form.

Summary – Taxon vs Clade

Taxon and clade are important parts of a phylogenetic tree. A taxon is any group in a biological classification into which the related organisms are classified by taxonomists. A clade is a group of organisms that comprises all evolutionary decedents of a common ancestor. This is the key difference between taxon and clade. Both units are extremely important to scientists in the phylogenetic analysis as they provide important information on the evolutionary relationship between different organisms.

Reference:

1. “Taxon.” Wikipedia, Wikimedia Foundation, 17 Apr. 2021, Available here.
2. “Clade.” Wikipedia, Wikimedia Foundation, 29 Mar. 2021, Available here.

Image Courtesy:

1. “pone.0068353.g003” By PLOS ONE PHYLOGENY (CC BY 2.0) via Flickr
2. “Clade in Phylogenetic Tree” By KaylaMSteen – Own work (CC BY-SA 4.0) via Commons Wikimedia