1. Objectives
Recognize the major sources of evidence for evolution.
Examine the pattern of features that reveal the history of a species.

2. KEY CONCEPT Evidence of common ancestry among species comes from many sources.

3. Vocabulary
Biogeography – study of the distribution of organisms around the world (311)
Homologous structures – body part that is similar in structure on different organisms but performs different functions (312)
Analogous structures – body part that is similar in function as a body part of another organism but is structurally different (313)
Vestigial structures – remnants of an organ or structure that functioned in an earlier ancestor (314)

4. Evidence for evolution in Darwin’s time came from several sources.
FOSSILS
- trace of an organism from the past.
Fossils in older layers are more primitive than those in the upper layers.

5. Geography
island species most closely resemble nearest mainland species
populations can show variation from one island to another
Biogeography – the study of the distribution of organisms around the world.

6. identical larvae, different adult body forms
Embryology
- The study of embryos
identical larvae, different adult body forms
similar embryos, diverse organisms
Larva
Adult barnacle
Adult crab

7. Anatomy
Homologous structures are similar in structure but different in function.
Homologous structures are evidence of a common ancestor.

8. Analogous structures have a similar function.
Human hand
Bat wing
Mole foot
Fly wing
Analogous structures are not evidence of a common ancestor.

9. Structural patterns are clues to the history of a species.
Vestigial structures are remnants of organs or structures that had a function in an early ancestor.
Ostrich wings are examples of vestigial structures.

10. Whales’ leg bones are another example of a vestigial structure that functioned in an early ancestor.
Leg bones – Vestigial Structure

11. Exit Ticket
List the four pieces of evidence for Evolution
How can Homologous structures be used to draw links between organisms?
Give an example of a vestigial structure