1. Theories of Evolution Department of Biology Mission Hills High School

2. What is Evolution? Changes in a population over time. Changes in a population over time. Changes may result in new types of organisms Changes may result in new types of organisms Results in extinction of other organisms. Results in extinction of other organisms. Considered a scientific fact that has occurred throughout the history of life. Considered a scientific fact that has occurred throughout the history of life.

3. Darwin’s Voyage Darwin was especially impressed with the organisms he saw on the Galapagos Islands west of South America: Darwin was especially impressed with the organisms he saw on the Galapagos Islands west of South America:

4. Galapagos Islands (Archipelago of Galapagos)

5. What is Natural Selection? What is Natural Selection? What does survival of the fittest mean? What does survival of the fittest mean? What might artificial selection be? What might artificial selection be?

6. Natural Selection Darwin based his theory of natural selection on noting that there was always competitions for food… Darwin based his theory of natural selection on noting that there was always competitions for food…

7. Natural Selection Those individuals well adapted to find food will win the competition by surviving and reproducing! (Struggle for Existence! Survival for the Fittest!) Those individuals well adapted to find food will win the competition by surviving and reproducing! (Struggle for Existence! Survival for the Fittest!)

8. What is the ultimate source of all of the variety within a gene pool? What is the ultimate source of all of the variety within a gene pool?

9. Mechanisms of Natural Selection Random gene mutations Random gene mutations Most mutation are neutral or harmful Most mutation are neutral or harmful Few may be favorable mutations in a population. Few may be favorable mutations in a population.mutations Some mutation may occur in genes called Homebox (HOX)genes. Result is usually appearance of a totally new trait. Some mutation may occur in genes called Homebox (HOX)genes. Result is usually appearance of a totally new trait.

10. How does the peppered moth population in England during the industrial revolution show microevolution? How does the peppered moth population in England during the industrial revolution show microevolution?

11. Natural selection result of environmental changes Before After

12. Selection and Distribution Stable environment has few members in the extreme ranges and more individuals with average ranges: Stable environment has few members in the extreme ranges and more individuals with average ranges: What is this curve called? What is this curve called?

14. Directional Selection Changes in the environment will act against one extreme and favor the other extreme.

15. Disruptive Selection Changes in the environment may favor only the extremes and act against the middle of the population. Extreme separations of the extremes may form separation of species.

16. Stabilizing selection Environment may go through long periods of stability. There is selection against the extremes and the favors the middle of the population

17. How is genetic drift different from natural selection? How is genetic drift different from natural selection?

18. Genetic Drift Change in the gene frequency due to an accidental change in the environment (fires, floods, volcanic eruptions, meteor impacts, etc…) Change in the gene frequency due to an accidental change in the environment (fires, floods, volcanic eruptions, meteor impacts, etc…) Usually affects small populations. Usually affects small populations.