1. Change over Time ©2008 Susan Anderson

2. Darwin  British Naturalist  Journey to Galapagos / South America  Saw: New/different SPECIES Fossils similar to living organisms  (where had these organisms gone?)  He asked why were those organisms on the islands different from those on the mainland?

3. Adaptations  Example for Darwin: Finches  Different beaks  Different foods  Less competition

4. Evolution  Gradual change over time to become better adapted to their environment. Gradualism Punctuated Equilibria

5. Natural Selection  “Survival of the Fittest”  Extinction  Overproduction – not all offspring survive  Competition- usually indirect (food, space)  Variations – genetic  Selection- helpful variations accumulate, unfavorable ones disappear

6. Formation of New Species  Sometimes a group is separated from the rest of its species. (river, mountain range, weather carries them)  If a group is separated long enough, they may evolve different traits.  “Geographic Isolation”

7. Continental Drift  Large scale geographic isolation.  Members were separated when the continents split.  Example: Animals isolated on Australia are unlike other mammals.

8. Review  What is evolution?  Name something Darwin observed that he thought was the result of evolution  Some insects look just like sticks. How could this be an advantage to the insects?  How could the “stick trait” have evolved through natural selection?

9. Fossil Record  Sedimentary Rock Most fossils are found in this type of rock Why?  Petrified Minerals dissolved in the water around remains soaks in and replaces the remains, changing them to rocks  Molds/Casts Remains get dissolved and leave behind a hollow space (mold), then it’s filled with minerals (cast)  Preserved Can be found in tar or amber

10. Dating Fossils  Relative Dating Only be used when the rock layers have been preserved in their original sequence Doesn’t tell actual age, only which fossils are older or younger  Absolute Dating Uses radioactive elements to determine exact age of fossils HALF LIFE – the time it takes for half the atoms of a sample to decay

11. Review  Describe how fossils form in sedimentary rock.  Explain the process of absolute dating.  How are gradualism and punctuated equilibrium similar?  How are gradualism and punctuated equilibrium different?

12. Other Evidence  Homologous Structures  Embryology  DNA similarities

13. Branching Tree Diagrams  A diagram the shows how scientists think different groups of organisms are related.

14. Review  Name three types of evidence from modern day organisms that scientists use to determine evolutionary relationships.  What are homologous structures?  Most scientists today consider similarities in DNA to be the best indicator of how closely two species are related. Why do you think this is the case?

15. Homework