Section 17.2 Summary – pages 450-459

1. Section 17.2 Summary – pages 450-459 Phylogenetic Classification: Models • The evolutionary history of a species is called its phylogeny (fy LAH juh nee). • A classification system that shows the evolutionary history of species is a phylogenetic classification and reveals the evolutionary relationships of species.

2. Section 17.2 Summary – pages 450-459 Cladistics • One biological system of classification that is based on phylogeny is cladistics (kla DIHS tiks). • Scientists who use cladistics assume that as groups of organisms diverge and evolve from a common ancestral group, they retain some unique inherited characteristics that taxonomists call derived traits.

3. Cladograms

4. Using a Cladogram • branches indicate development of new or significantly different traits • groups that are closer together on the cladogram probably share a more recent common ancestor than groups that are farther apart. • groups that are closer together on the cladogram probably share a more recent common ancestor than groups that are farther apart.

5. Fan Diagrams • do not show direct ancestry, just a probable sequence • can show time line and numbers of organisms in related groups • organisms that are closer in the same colored ray share more characteristics