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

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

3. Evidences for evolution
2. Fossils—traces of organisms from the past
Fossils in older layers are more primitive than those in the upper layers.

4. Paleontology provides evidence to support evolution.

5. 3. Embryology: The study of the developing embryo.
Different organisms go through similar stages in the developing embryo
*Gill slits
*Tails

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

7. 4. Anatomy-study of body structures
A. Homologous structures are similar in structure but may be different in function.
Homologous structures are evidence of a common ancestor.
Human hand
Bat wing
Mole foot

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

9. C. Vestigial structures are remnants of organs or structures that no longer serve a purpose.
Ostrich wings are examples of vestigial structures.

10. --Whale legs

11. In humans:
Wisdom teeth
Ear muscles
Tail bone
Nictitating membrane

12. Biochemical Similarities
5. Molecular Similarities-Two closely-related organisms will have similar DNA sequences, proteins, etc.

13. *Hox genes indicate a very distant common ancestor.
Genetic Similarities- certain genes are found in many organisms, from fruit flies to humans
*Hox genes indicate a very distant common ancestor.
*control the development of specific structures