What is the Difference Between Synapomorphy and Symplesiomorphy

The main difference between synapomorphy and symplesiomorphy is that in synapomorphy, two or more taxa share a character with their recent common ancestor while, in symplesiomorphy, the character shared by the two or more taxa occurs in their earliest common ancestor. Furthermore, synapomorphy describes a derived character while symplesiomorphy describes an ancestral character.

Synapomorphy and symplesiomorphy are two types of characters used in the identification of organisms, classifying in them into phylogenetic trees.

Key Areas Covered

1. What is Synapomorphy
     – Definition, Type of Character, Examples
2. What is Symplesiomorphy
     – Definition, Type of Character, Examples
3. What are the Similarities Between Synapomorphy and Symplesiomorphy
     – Outline of Common Features
4. What is the Difference Between Synapomorphy and Symplesiomorphy
     – Comparison of Key Differences

Key Terms

Ancestral Character, Apomorphy, Derived Character, Symplesiomorphy, Synapomorphy

What is Synapomorphy

A synapomorphy is a character or trait shared by two or more taxa, which is also shared with their most recent common ancestor. Therefore, this character or trait is a derived one during the recent evolutionary history. However, apomorphy is another type of character only present in specific taxa. Further, this type of characters helps to distinguish a particular taxon among the other taxa and from its common ancestor. Moreover, a synapomorphy is a type of shared apomorphy.

Figure 1: Synapomorphy

For example, the vertebral column is a highly conserved character in mammals. Even giraffes with long necks or other mammals with short necks have the same number of vertebrae in their necks. This is an example of synapomorphy. However, mammals that belong to the Afrotheria clade, including elephant shrews, golden moles, and elephants have increased number of thoracolumbar vertebrae. Hence, this is an apomorphy in that clade.

What is Symplesiomorphy

Symplesiomorphy is a character or trait shared by two or more taxa with their earliest common ancestor. Therefore, this type of characters is known as ancestral characters as they have been shared through a long evolutionary history. Significantly, plesiomorphy is a situation when a character is not unique to that particular taxa. Symplesiomorphy is the shared plesiomorphy. The main importance of a symplesiomorphic character is that it gives a strong hint about the evolutionary relationship to an earliest common ancestor.

Figure 2: Relationship among Cladistics

For example, both bony fish and cartilaginous fish share the character of breathing through gills. However, bony fish are more related to terrestrial vertebrates, not to cartilaginous fish. This claims that terrestrial vertebrates might develop gills for respiration during their evolutionary history. But, they have lost that character through their evolution. Therefore, respiration through gills is an ancestral character which is symplesiomorphic.

Similarities Between Synapomorphy and Symplesiomorphy

• Synapomorphy and symplesiomorphy are two types of characters of living organisms.
• They provide evidence about the similarities between recent taxa.
• Also, both help to characterize and classify organisms.

Difference Between Synapomorphy and Symplesiomorphy

Definition

Synapomorphy refers to a characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants while symplesiomorphy refers to an ancestral character (trait-state) shared by two or more taxa. Thus, this is the main difference between synapomorphy and symplesiomorphy.

Evolution History

While synapomorphy describes a derived character, symplesiomorphy describes an ancestral character. Hence, this is another important difference between synapomorphy and symplesiomorphy.

Sharing with the Ancestor

Also, one other difference between synapomorphy and symplesiomorphy is that in synapomorphy, the character is shared by the most recent common ancestor while in symplesiomorphy, the character is shared by the earliest common ancestor.

Examples

The presence of the same number of vertebrae in the necks of mammals and giraffes is an example of synapomorphy while the presence of a vertebral column in mammals and other vertebrates is an example of symplesiomorphy. This is also a difference between synapomorphy and symplesiomorphy.

Conclusion

A synapomorphy is a type of character shared by two or more taxa. Also, this character is present in their recent common ancestor. Therefore, synapomorphy is a derived character. In comparison, symplesiomorphy is another type of character shared by two or more taxa. Significantly, the second character is shared with the earliest common ancestor of the taxa. Therefore, this character is an ancestral character. Hence, the main difference between synapomorphy and symplesiomorphy is the sharing of the character with ancestor taxa.

References:

1. “Synapomorphy- an Overview.” ScienceDirect Topics, Elsevier B.V., Available Here.
2. Chavan, Akshay. “Symplesiomorphy.” BiologyWise, BiologyWise, 9 Dec. 2017, Available Here.

Image Courtesy:

1. “Synapomorphy” By Ferahgo the Assassin – Own work (CC BY 3.0) via Commons Wikimedia  
2. “Cladistics-Apomorphy” By Faustnh (Faustino Núñez Hernández) – Own work by uploader, Faustino Núñez Hernández (CC BY 3.0) via Commons Wikimedia