A shared derived character, also known as a synapomorphy, is a trait that is present in two or more groups but is absent in their last common ancestor. This concept is fundamental in the field of evolutionary biology and systematics, as it helps scientists identify evolutionary relationships between organisms.
For example, consider birds and bats. Both share the derived characteristic of having wings, which distinguishes them from their last common ancestor that did not have wings. Identifying shared derived characters allows researchers to construct cladograms, which are diagrams that represent evolutionary relationships based on shared traits. In essence, these characters highlight the evolutionary divergence that occurs over time, showing how different species with a common ancestor have adapted and evolved unique features.