Question

What is synapomorphy?

Answer 1

It is related to the phylogenetic study where the character is derived from the ancestors but is different from them. It is a result of evolution and can be studied in detail with the help of the phylogenetic tree.

Complete answer
The phylogenetic system can be represented via a diagram known as phylogenetic trees. The evolution of various species or groups and their common ancestry can be studied by them along with the relation among different organisms. Synapomorphy is also known as the apomorphy in which a character or a trait is derived from the ancestors during the course of evolution but the new character developed is found to be different from the older one. They can be studied via the phylogenetic tree and are placed under the different clades.
Synapomorphy is said to be the shared amorphic characters that can be classified on the basis of different clades. Thus the clades of these organisms constitute mostly a single common character which is the most recent one.
Examples: The number of the vertebrae in the case of the humans and camels that came under the mammals are the same while the elephants, moles that come under different clades have more vertebrae. Thus both of the clades share a common ancestral character and show the Synapomorphy.

Additional information
-Cladistics is the most common method of incorporating information into phylogenetic trees. In 1950, Wiki Henning was the one who accepted it widely and then developed it.
-The word cladistics means cladogram from which the word clade is derived.
-The fewer species that come under the small clades that have the common ancestors while the larger number of species that come under the large clades will have the same ancestral characters.

Note:
Phylogenetic tree or the phylogeny can be called an evolutionary tree used for determining evolutionary relationships. In the study of various diseases that include HIV, this phylogenetic relationship among the species is taken into account. This study will result in the formation of a cladogram which is a tree-like structure and is based on the evolution of ancestors.