II. Darwin’s Contributions A. Overview B. Argument: Evidence for Evolution by Common Descent

1. II. Darwin’s Contributions A. Overview B. Argument: Evidence for Evolution by Common Descent C. Mechanism: Natural Selection D. Dilemmas: “Long before having arrived at this part of my work, a crowd of difficulties will have occurred to the reader. Some of them are so grave that to this day I can never reflect on them without being staggered; but, to the best of my judgment, the greater number are only apparent, and those that are real are not, I think, fatal to my theory.” – Charles Darwin, The Origin of Species (1859).

2. II. Darwin’s Contributions A. Overview B. Argument: Evidence for Evolution by Common Descent C. Mechanism: Natural Selection D. Dilemmas: 1. The evolution of complex structures – addressing Paley “Can we believe that natural selection could produce, on the one hand, organs of trifling importance, such as the tail of a giraffe, which serves as a fly-flapper, and, on the other hand, organs of such wonderful structure, as the eye, of which we hardly as yet fully understand the inimitable perfection?”– Charles Darwin, The Origin of Species (1859).

3. II. Darwin’s Contributions A. Overview B. Argument: Evidence for Evolution by Common Descent C. Mechanism: Natural Selection D. Dilemmas: 1. The evolution of complex structures “To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. Charles Darwin, The Origin of Species (1859).

4. Dawkins: Evolution of the Camera Eye

5. D. Dilemmas: 1. The evolution of complex structures

6. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? “…why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms? Why is not all nature in confusion instead of the species being, as we see them, well defined? … as by this theory innumerable transitional forms must have existed, why do we not find them embedded in countless numbers in the crust of the earth?” – Charles Darwin, The Origin of Species (1859)

7. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? ? X X X ? X X X

8. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? “As natural selection acts solely by the preservation of profitable modifications, each new form will tend in a fully-stocked country to take the place of, and finally to exterminate, its own less improved parent or other less-favoured forms with which it comes into competition. Thus extinction and natural selection will, as we have seen, go hand in hand. Hence, if we look at each species as descended from some other unknown form, both the parent and all the transitional varieties will generally have been exterminated by the very process of formation and perfection of the new form.” –,The Origin of Species (Darwin 1859)

9. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? X Better adapted descendant outcompetes ancestral type X

10. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? X X Better adapted descendant outcompetes ancestral type X X

11. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? X X X Better adapted descendant outcompetes ancestral type X X X

12. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? ? X X X “…I believe the answer mainly lies in the record being incomparably less perfect than is generally supposed…” - Charles Darwin, The Origin of Species (1859) X X X

13. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? 1861 – Archaeopteryx lithographica “…and still more recently, that strange bird, the Archeopteryx, with a long lizardlike tail, bearing a pair of feathers on each joint, and with its wings furnished with two free claws, has been discovered in the oolitic slates of Solenhofen. Hardly any recent discovery shows more forcibly than this, how little we as yet know of the former inhabitants of the world.” – Charles Darwin, The Origin of Species, 6th ed. (1876)

14. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? 3. What is the source of heritable variation?

15. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? 3. What is the source of heritable variation? "These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the external conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection…". - The Origin of Species (Darwin 1859). - Inheritance of acquired characters – (wrong) - Use and disuse – (sort of, but not as he envisioned it) - Blending heredity and the action of selection should reduce variation in a population over time. - gemmules and grafting experiments….

16. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? 3. What is the source of heritable variation? 4. How do instincts evolve? - if there is heritable variation in behavior, then selection can act on that, also…

17. D. Dilemmas: 1. The evolution of complex structures 2. Where are modern and fossil intermediates? 3. What is the source of heritable variation? 4. How do instincts evolve? 5. How can sterility, and the evolution of entire sterile castes (like in social insects) evolve? - Sterile organisms don’t reproduce; how can they be favored by selection? Some form of group selection… groups with steriles do bet and their reproductives outperform the combined reproductive success of sexual competitors.

18. II. Darwin’s Contributions A. Overview B. Argument: Evidence for Evolution by Common Descent C. Mechanism: Natural Selection D. Dilemmas: E. Darwin’s Model of Evolution

19. II. Darwin’s Contributions A. Overview B. Argument: Evidence for Evolution by Common Descent C. Mechanism: Natural Selection D. Dilemmas: E. Darwin’s Model of Evolution Sources of VariationAgents Causing Evolution ? Natural Selection V A R I A T I O N

20. III. Post-Darwinian Developments A. Physics 1. The Age of the Earth a. 1862 - William Thompson - "Lord Kelvin“ - Earth was 15-20mya. b. 1896 - Henri Becquerel - discovers emission of Uranium c. 1903 - Pierre and Marie Curie - discover emission from new element - Radium d. 1904 - Ernst Rutherford - "The discovery of the radio-active elements, which in their disintegration liberate enormous amounts of energy, thus increases the possible limit of the duration of life on this planet, and allows the time claimed by the geologist and biologist for the process of evolution."

21. III. Post-Darwinian Developments A. Physics 1. The Age of the Earth 2. Radioactive Decay and Geological Clocks - measure amt of parent and daughter isotopes = total initial parental - with the measureable1/2 life, determine time needed to decay this fraction - K40-Ar40 suppose 1/2 of total is Ar40 = 1.3by (Now, you might say "be real"! How can we measure something that is this slow?) Well, 40 grams of Potassium (K) contains: 6.0 x 1023 atoms (Avogadro's number, remember that little chemistry tid-bit?). So, For 1/2 of them to change, that would be: 3.0 x 1023 atoms in 1.3 billion years (1.3 x 109) So, divide 3.0 x 1023 by 1.3 x 109 = 2.3 X 1014 atoms/year. Then, divide 2.3 x 1014 by 365 (3.65 x 102) days per year = 0.62 x 1012 atoms per day ( shift decimal = 6.2 x 1011) Then, divide 6.2 x 1011 by 24*60*60 = 86,400 seconds/day: (= 8.64 x 104) = 0.7 x 107 atoms per second 0.7 x 107 = 7 x 106 = 7 million atoms changing from Potassium to Argon every second!!!

22. III. Post-Darwinian Developments A. Physics B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition FISH AMPHIBIANS Ichthyostega - Struts in the tailfin (FISH) - Feet (AMPHIBIANS) - After fish, before amphibians (just where evolution predicts it should be) XXX

23. D. Devonian (417-354 mya) - Placoderms - Sharks - Lobe-finned Fishes 365 mya 385 mya

24. III. Post-Darwinian Developments A. Physics B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition

25. Eusthenopteron

26. Tiktaalik roseae

27. Acanthostega gunnari

28. Ichthyostega sp.

29. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds Archeopteryx lithographica REPTILES BIRDS XXX – 150 mya • - Fingers, teeth, tail (Reptiles) • Feathers (birds) • - After reptiles, before birds (just where evolution predicts it should be)

30. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds

31. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds Epidipteryx – 165 mya

32. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds Microraptor – 120 mya

33. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds Anchiornis – 160mya

34. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds Sinosauropteryx – 120mya

35. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds Tianyulong – 200 mya

37. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds 3. The evolution of mammals Therapsids REPTILES MAMMALS • - Mammalian skeleton • Intermediate ear • primitive dentition • - After reptiles, before mammals (just where evolution predicts it should be) XXX

38. Mammals from the Jurassic (185 mya) Therapsids from the Permian (280 mya) to the Triassic (200mya) Pelycosaur Reptiles of the Carboniferous (300 mya)

39. B. Paleontology and Transitional Fossils 1. Ichthyostegaand the fish-amphibian transition 2. The evolution of birds 3. The evolution of mammals 4. The evolution of humans Australopithecines APES HUMANS - After apes, before humans (just where evolution predicts it should be) • bipedal (human trait) • chimp-sized cranial volume XXX

40. 4. The evolution of humans Australopithecines Australopithecus afarensis

41. 4. The evolution of humans Teeth

42. Legs 4. The evolution of humans

43. 4. The evolution of humans Skulls

44. 4. The evolution of humans

45. III. Post-Darwinian Developments A. Physics B. Paleontology and Transitional Fossils C. Geology

46. III. Post-Darwinian Developments A. Physics B. Paleontology and Transitional Fossils C. Geology Continental Drift - 1915 - Alfred Wegener

47. - Not accepted until the 1960’s and 1970’s, when sea floor spreading was observed, sonar was used to map the ocean, and paleomagnetism demonstrated where continents had been in the past relative to magnetic north.

48. Explained disjunct distributions as a consequence of “vicariance”

49. III. Post-Darwinian Developments A. Physics B. Paleontology and Transitional Fossils C. Geology D. Genetics and Population Genetics 1. Heredity and Variation Hereditary units are ‘particulate’, and Chromosomes assort independently during gamete formation. Sexually reproducing species can produce an extraordinary amount of genetic variation in their offspring as a consequence of passing on different combinations of chromosomes and genes. A single pair of humans can produce any of 246 (~70 trillion) combinations of chromosomes in their offspring.

50. D. Genetics and Population Genetics 1. Heredity and Variation 2. Genetic Tests/Analyses of Phylogeny - gross chromosomal patterns