1. Evolution

2. Geologic change Catastrophism: natural disasters shaped landforms and caused species to become extinct Gradualism: landform shaping is the result of gradual changes. Uniformitarianism: processes that shape Earth are uniform through time

3. Early Ideas Buffon: shared ancestor theory Erasmus Darwin: common ancestor Lamarck: inheritance of acquired characteristics

4. Darwin’s Observations Variation: not all members of a species or a population are identical Adaptation: a feature that allows an organism to better survive over time

5. Artificial Selection Organisms are bred to produce desirable traits

6. Natural Selection Organisms with unfavorable traits will die out, so the favorable traits are passed on

7. How Natural Selection Works Variation within a population Many more young are born than can survive Individuals best suited to the environment will survive to pass their genes on. Descent with modification: Over time, small changes build up

8. Evidence for Evolution Fossils Geography Embryology Anatomy Vestigial structures

9. Population Evolution Gene pool: all the alleles of all the individuals in the population Allele frequency: how common a specific allele is in the population

10. Genetic variation Mutation: random change in DNA Recombination: like in meiosis of sexual reproduction Hybridization: crossing two different species that contain common genes.

11. Natural selection in populations Normal distribution: most are average, few are extreme. The bell curve.

12. Disruptive selection: The mean is selected against

13. Stabilizing selection: Both extremes are selected against

14. Directional selection: an extreme is selected against

15. Comparison of selection models

16. Other mechanisms Gene flow: migration moves alleles between populations Genetic drift: when some alleles become fixed or disappear due to small population size. Allele frequencies are different. Bottleneck effect: when a population size decreases rapidly, genetic diversity also decreases. When the population rebounds, it has less diversity.

17. Founder effect: when a small number of individuals colonize a new area, the new gene pool is different from the original. Sexual selection: how females choose their mate Intrasexual: competition among the males Intersexual: primping

18. Sexual selection Winner gets the girl Ain’t I pretty