Within a lineage, the largest number of shared derived characters should be found among two organisms that are members of the same species.

Here's why:

* Derived characters are features that evolved in a recent ancestor and are shared by its descendants.

* Species are defined as groups of organisms that can interbreed and produce fertile offspring.

* Members of the same species are more closely related to each other than to members of different species. This means they share a more recent common ancestor and therefore have more shared derived characters.

For example, all mammals share derived characters like mammary glands, hair, and a warm-blooded metabolism. But within the mammal lineage, two species of bats will share even more derived characters than a bat and a human, because the bats are more closely related.