1. Darwin’s Theory of Evolution

2. Historical Context (early 1800s) Aristotle, Judeo-Christian culture, book of Genesis… – The earth is only 6000 years old – All living species are “static” (put here ‘as is’)

3. Pre-Darwin Lamarck (early 1800s) Buffon Inheritance of Acquired Characteristics

4. Inheritance of Acquired Characteristics Why do giraffes have long necks? Because they stretch them during their lifetime, then their offspring have long necks The theory of “Use & Disuse”

5. Who was Darwin? Surgeon in training Minister Recruited by captain of HMS Beagle Set sail in 1831 at the age of 22

6. Not just the Galapagos…

7. Not just finches…

8. Darwin made 3 main observations… 1. Members of a population vary in their physical traits. 2. Many physical traits are inherited from parent to offspring. 3. All species are capable of reproducing more offspring than the environment can support.

9. And drew 2 conclusions: 1. Individuals who inherit traits that give them a better chance of surviving tend to leave more offspring than other individuals 2. This unequal reproduction of offspring causes ‘favorable’ traits to accumulate in a population over generations. (“survival of the fittest; struggle for existence)

10. Darwin called these conclusions “Descent with Modification” We call it “Natural Selection”

11. Important!! What is ‘favorable’ in one environment may not be in another environment. The environment determines what is favorable and unfavorable.

12. 4 Take-home Points about Natural Selection 1. Individuals DO NOT evolve. Evolution refers to generation-to- generation changes in a population. 2. Natural selection can only amplify or diminish traits that are inheritable.

13. 4 Take-home Points about Natural Selection 3. Evolution is NOT goal-directed. No notion of “perfect species.” Environmental factors vary in place & time…’favorable’ traits will also vary.

14. 4 Take-home Points about Natural Selection 4. Evolution is about compromise.

15. It’s all about timing… Darwin formulated his idea of natural selection in the early 1840s. He did not publish them until 1858. Conflict! Alfred Wallace

16. What Data did Darwin collect? (i.e., what is the evidence for evolution?) 1. Fossil Record 2. Biogeography 3. Comparative Embryology 4. Comparative Anatomy 5. Molecular Biology

17. A Skull of Homo erectus B Ammonite castsC Dinosaur tracks Fossilized organic matter of a leaf E Insect in amber F “Ice Man” D 1. The Fossil Record

18. Pelvis and hind limb Rhodocetus (predominantly aquatic) Pakicetus (terrestrial) Dorudon (fully aquatic) Balaena (recent whale ancestor) Pelvis and hind limb

19. North America = Living lungfishes Australia Africa Asia Europe South America = Fossilized lungfishes 2. Biogeography

20. Present Eurasia Millions of years ago 65.5 135 251 Mesozoic Cenozoic Paleozoic Madagascar India Australia Africa Antarctica South America North America Laurasia Gondwana Pangaea

21. 2. Biogeography All the species of finches on the Galapagos Islands look like finches native to the West Coast of South America—but not exactly the same “Adaptive Radiation”

22. Pharyngeal pouches Post-anal tail Chick embryo Human embryo 3. Comparative Embryology

23. Humerus Radius Ulna Carpals Metacarpals Phalanges HumanCatWhaleBat 4. Comparative Anatomy Homologous Structures = Divergent Evolution

24. Pelvis and hind limb Dorudon (fully aquatic) Balaena (recent whale ancestor) Pelvis and hind limb 4. Comparative Anatomy Vestigial Structures: What are left of homologous structures

25. Dorudon Balaena

26. Modern-Day Humpback Whale

27. Analogous Structures = Convergent Evolution Homologous Analogous

28. 5. Molecular Biology http://www.geneticorigins.org/mito/media2.html http://evolution.berkeley.edu/evosite/evo101/IIE1cMolecularclocks.sht ml Comparison of DNA sequences from different organisms is very helpful in determining relationships. Molecular analysis is best done together with other types of analyses.