1. Ch. 22 NATURAL SELECTION

2. SPECIES CHANGES OVER TIME

3.  http://www.youtube.com/watch?v=gZpsVSVRsZk http://www.youtube.com/watch?v=gZpsVSVRsZk CARL SAGAN EXPLAINS EVOLUTION

4. Ch 22.1 EVOLUTIONARY THOUGHT

5.  1796: Fossil Record  Living elephant jaw vs. fossil (mammoth & mastodon) jaws  The deeper the fossils, the more dissimilar to living organisms GORGES CUVIER’S CONTRIBUTION

6.  1795: Gradualism  profound geological change occurs through slow/continuous process JAMES HUTTON’S CONTRIBUTION

7.  1830: Uniformitarianism  geologic processes of today are the same as in the past CHARLES LYELL’S CONTRIBUTION

8.  Layers of the Earth show a consistently aging planet  Organisms living during the past have been preserved  Nearly all fossilized species are extinct  Therefore: life evolves as the environment changes BIG PICTURE

9.  Mechanism: Use and disuse & acquired characteristics LAMARCK'S CONTRIBUTION

10.  Mechanism: Natural Selection CHARLES DARWIN’S CONTRIBUTION

11.  Mechanism: Natural Selection  Co-published w/ Darwin ALFRED WALLACE’S CONTRIBUTION

12.  Evolution by natural selection explains… BIG PICTURE

13. PAST: ORGANISMS HAVE GONE EXTINCT

14. PRESENT: DIVERSITY OF LIFE ON EARTH

15. FUTURE: SPECIES CONTINUE TO EVOLVE

16.  Law of Superposition:  Newer layers of sediment are deposited on top of older layers  Biogeography:  Where common fossils are found  Radiometric Dating:  Radioactive isotopes decay at a constant rate over time ARCHAEOLOGY TODAY

17. Ch 22.2 DARWIN EXPLAINS NATURAL SELECTION

18. DARWIN’S LIFE  1809-1831  Lived in England & fascinated with nature  Went to school to became a physician  Dropped out (disgusted by surgery)  Became a clergyman  1831-1836  Invited on the HMS Beagle  Hydrographic survey of South America

19. DARWIN OBSERVES  Documented  Kept a Journal: The Voyage of the Beagle  Collected  Thousands of plants, animals, & fossils

20. ON THE ORIGIN OF SPECIES  1836-1859  Thinks about the voyage, animal/plant collection, fossils, geology…  Begins to describe the most revolutionary idea in biology  Receives a letter from colleague Alfred Wallace with same idea  They publish their idea together  Then Darwin finishes his book

21. WE CHANGE ORGANISMS  Artificial Selection:  humans modify species over many generations by selecting and breeding individuals with desired traits

22. WE CHANGE ORGANISMS

23. OBSERVATIONS FROM THE VOYAGE  Galapagos islands, while close to each other, contained:  Various ecosystems  Organisms similar to, but different from each other  Each had adaptations to fit the environment

24. OBSERVATIONS 1.For any species, population sizes would increase exponentially if all individuals born reproduce successfully 2.Populations tend to be stable in size, except for seasonal fluctuations 3.Resources are limited

25. INFERENCE #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

26. OBSERVATIONS 4.Members of a population vary extensively in their characteristics 5.Much of this variation is heritable

27. INFERENCE #2  Survival depends in part 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

28. INFERENCE #3  This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations

29. SUMMARY OF EVOLUTION BY NATURAL SELECTION  Organisms better suited to the environment are more likely to survive & reproduce than organisms less suited to the environment Mutation  Variation  Selection Individuals do NOT change; populations change

30. EVOLUTION BY NATURAL SELECTION There is a grandeur in this view of life…