Final answer:
A derived trait, also known as a derived character, is a trait that has evolved in a more recent organism. These traits are used to determine the relationships between different species or clades in phylogenetic trees.
Step-by-step explanation:
A derived trait, also known as a derived character, is a trait that has evolved or appeared in a more recent organism. It is a characteristic that distinguishes one group of organisms from another. In the context of phylogenetic trees, derived traits are used to determine the relationships between different species or clades.
For example, in the evolutionary history of mammals, the presence of hair is a derived trait that distinguishes them from other groups of animals. This trait evolved in a more recent ancestor of mammals and is not found in more distant ancestors such as reptiles or amphibians.
It's important to note that whether a trait is considered ancestral or derived depends on the specific organisms being compared and the diagram or phylogenetic tree being used.