1. Chapter 18 Classification

2. Section 18-2: Modern Phylogenetic Taxonomy • Systematics organizes the tremendous diversity of living things in the context of evolution. • This area of study utilizes phylogenetic trees which is a family tree that shows the evolutionary relationship thought to exist among groups of organisms.

4. Section 18-2: Modern Phylogenetic Taxonomy • The fossil record is commonly used to establish evolutionary links between organisms that no longer exist.

5. Section 18-2: Modern Phylogenetic Taxonomy • The fossil record is commonly used to establish evolutionary links between organisms that no longer exist.

6. Section 18-2: Modern Phylogenetic Taxonomy • The morphology of organisms also acts as evidence of a common evolutionary history.

7. Section 18-2: Modern Phylogenetic Taxonomy • Embriological evidence is also used by scientists to help classify organisms. • The general development of embryos is the same. • There are however a few stages early on that serve as divisions among organisms

8. Section 18-2: Modern Phylogenetic Taxonomy • Within a matter of hours of conception a ball of cells known as a blastula forms. • A blastospore, small indention, develops on the outside of the blastula; this will become the anterior end of the digestive system in some organisms and the posterior end in others. • These developmental differences imply a relative closeness in organisms that develop in the same form.

9. Section 18-2: Modern Phylogenetic Taxonomy • Karyotypes of organisms can now be used to compare organisms DNA and RNA. • Similar banding shows a common evolutionary history and therefore a close relationship among the two organisms.

10. Section 18-2: Modern Phylogenetic Taxonomy • The newest form of phylogenetic classification is called cladistics. • It looks at derived characters or features that apparently developed only within the group under consideration.

11. Section 18-2: Modern Phylogenetic Taxonomy • An ancestry diagram in which cladistics evidence is laid out for evaluation is called a cladogram.