2. Evidence for evolution

3. Darwin’s key ideas: A. REPRODUCTION: Organisms produce more offspring than can survive B. VARIATION:Variety in traits exist C. SURVIVAL OF THE FIT: Some traits allow survival & are passed on D. Over time certain variations make up most of a population & they may be different from their ancestors

4. Evidence for Evolution 1. Fossil record 2. Comparative anatomy 3. Comparative embryology 4. Comparative biochemistry 5. Plate tectonics

5. Fossil Evidence : Remains of once living organisms provide evidence of change over time. Limited: 1. Type of material preserved (bone, shell, impressions, amber) 2. Incomplete record 3. Easily disrupted

6. Plant Fossil Evidence:

7. Law of superposition

8. Comparative Anatomy: Structural similarities link related species

9. Homologous Structures: Same underlying structures, different functions, different environments & common ancestor

10. Homologous structures in plants

11. Vestigial Structures Structures that are present in an organism but are reduced in size and either have no use or have a less important function than they do in other related organisms.

13. Snake Human

14. Comparative embryology : Similar embryo development in closely related species

15. 5.Comparative Biochemistry Similar DNA sequences code for similar traits in closely related species.

17. Plate Tectonics (Geographical distribution) Continental masses were one land mass

18. Closely related species have common ancestors on now separated continents