1. History of Evolution Chapter 9

2. Which came first?

3. Recall: Hutton & Lyell’s Contribution  Profound geologic processes of today are the same as in the past

4. Recall: Lamarck’s Contribution  Life evolves as environment changes  Acquired traits can be passed to offspring  Use and disuse – use it and it gets better/bigger, don’t and it gets worse/smaller  Thus, no extinction exists

5. Recall: Malthus’ Contribution  Populations produce more offspring than can possibly survive to reproduce  Remember carrying capacity?

6. Recall: Mendel’s Contribution  Traits are passed from parents to offspring  There is variation of traits within populations

7. Darwin Connects the Pieces  Collected thousands of plants & animals on Beagle voyage (ended October, 1835) Each had wondrous adaptations  On the Origin of Species published November, 1859

8. Observation  Members of a population vary extensively in their characteristics no two individuals are exactly alike (DNA)

9. Observation  Much of this variation is heritable

10.  For any species, population sizes would increase exponentially if all individuals that are born survived and reproduced successfully Observation

11.  Resources are limited

12. Big Idea #1  Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving

13. Big Idea #2  Differential survival and reproduction Survival depends on inherited traits; individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals

14. Big Ideas 1 & 2 = Big Idea #3  This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population  Favorable characteristics accumulate over generations

15. Natural Selection  Organisms better suited to the environment are more likely to survive and reproduce than organisms less suited to the environment

16. Natural Selection

18. Natural Selection Leads To Diversity

19. Therefore…  A non-chicken ancestor laid an egg in which a genetic mutation occurred and developed over many generations into Earth’s first chicken.  Video Video

20.  5 Fingers of Evolution 5 Fingers of Evolution