Shared derived character state is called

The correct answer is synapomorphy

Concept:

• In phylogenetics, a shared derived character state refers to a trait that is shared by two or more taxa and is derived from their most recent common ancestor.
• This concept is crucial for constructing phylogenetic trees and understanding evolutionary relationships among different organisms.
• Characters can be classified based on their evolutionary origins and the groups they define.

Explanation:

• Synapomorphy: A synapomorphy is a shared derived character state that is present in an ancestral species and shared exclusively by its evolutionary descendants. This trait is used to define a clade, a group of organisms that includes an ancestor and all its descendants. For example, the presence of feathers in birds is a synapomorphy that defines the clade Aves.
• Apomorphy: An apomorphy is a derived character state that is unique to a particular taxon. It indicates evolutionary novelty. However, it is not necessarily shared with other taxa, making it less useful for defining shared evolutionary relationships.
• Symplesiomorphy: A symplesiomorphy is a shared ancestral character state. It is a trait that is found in the common ancestor of a group but is not unique to that group. This makes it less useful for defining specific evolutionary relationships. For example, the presence of a vertebral column is a symplesiomorphy for vertebrates.
• Plesiomorphy: A plesiomorphy is an ancestral character state. It is a trait that was present in the ancestor of a group but may have been altered or lost in some descendants. Plesiomorphies do not provide information about the derived relationships within a group.