Biology 18.2

1. Modern Evolutionary Classification 18.2

2. Phylogen y The study of evolutionary relationships among organisms.

3. Evolutionary Classification Method of grouping organisms together according to their evolutionary history.

4. Derived Character Characteristic that appears in recent parts of a lineage, but not in its older members.

5. Cladogram Diagram that shows the evolutionary relationships among a group of organisms.

6. Molecular Clock Model that uses DNA comparisons to estimate the length of time that two species have been evolving independently.

7. Key Concept How are evolutionary relationships important in classification? Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.

8. Key Concept How can DNA and RNA help scientists determine evolutionary relationships? The genes of many organisms show important similarities at the molecular level. Similarities in DNA can be used to help determine classification and evolutionary relationships.