1. Origin of Life 004b

3. Universe formed 15 billion years ago (Big Bang) Galaxies formed from stars, dust and gas Earth formed 4.6 billion years ago

4. Earth 3.5 bya

5. Suns energy stripped away 1 st atmosphere 2 nd atmosphere formed from volcanic outgassing Primitive atmosphere: CO 2, water vapor, lesser amts of CO, N 2, H 2, HCl, and traces of NH 3 and CH 4 (3.5 bya)

6. O 2 came in 3.2-2 bya Autotrophic Organisms: photosynthesis Another environmental change Result in evolution

7. Earth’s Atmosphere

8. Oxygen Evidence for O 2 production:  Banded Iron Formations (BIF)  BIF found in ocean sediments red bands are high in Fe 2 O 3 and Fe 3 O 4 (red bands)- forms when reduced iron reacts with O 2

9. “Oxygen revolution” Time (billions of years ago) 4 3 2 1 0 1,000 100 10 1 0.1 0.01 0.0001 Atmospheric O 2 (percent of present-day levels; log scale) 0.001 Oxygen

10. Evolution of Ozone Accumulation of free O 2 in the atm also led to the accumulation of ozone –Ozone important for blocking incoming UV radiation Even small amounts of atm O 2 leads to enough ozone to provide some protection against UV –Partial screen likely to have formed ~ 1.9 bybp –Presence of this UV filter allowed life to move out of the oceans and onto land –Consistent with the timing of evolution of eukaryotes and higher plants

12. 0.5 billion years ago Atmosphere O 2 to 1% current Compare to present: 78% N 2, 21% O 2, 0.04% CO 2, + trace gasses Relatively small, most single cell Start of multicellularity Increase in cell complexity

13. Formation of Earth’s Oceans (4 bybp): Rain Condensation Off gassing of water vapor from volcano

15. Life began~ 3.5 bya Organic molecules (C H O N P S) swimming in shallow seas Stage 1: Abiotic synthesis of organic molecules such as proteins, amino acids and nucleotides

16. Stage 2: joining of small molecules (monomers) into large molecules

17. Stage 3: origin of self-replicating molecules that eventually made inheritance possible

18. Stage 4: packaging these molecules into pre-cells, droplets of molecules with membranes that maintained an internal chemistry

19. Thomas Huxley- Search for origin of life Wyville Thompson: HMS Challenger (1872-1876) found it was actually diatomacous ooze reacting with seawater and ethyl alcohol Bathybias heckali- primordial ooze

20. Miller and Urey’s Experiment ELECTRICITY!!! Organic molecules like amino acids

21. Produced: 20 amino acids Several sugars Lipids Purine and pyrimidine bases (found in DNA, RNA & ATP)

22. RNA world The first genetic material was probably self- replicating, catalytic RNA not DNA; In “RNA world”, RNA could have provided the template on which DNA was assembled Once DNA appeared “RNA world” gave way to “DNA world” The first organisms were not photosynthetic; they were probably heterotrophic

23. Protobionts, collections of abiotically produced molecules surrounded by a membrane-like structures Liposomes can form when lipids or other organic molecules are added to water. - Have a bilayer - Can undergo osmosis - Can “reproduce”

24. Protocell (Protobiont) Fatty acid membrane with ribozymes inside

25. Oxygen Earliest Evidences: oldest fossils  Oldest photosynthetic microbes 3.5-3.2 B.Y. - Bacterium-like - Unicellular - Evidence for breakdown products of photosynthesis  Cyanobacteria, 3.5 B.Y.  Stomatolites, 3.5- 0.7 B.Y.

26. Three-domain system ExtremophilesProkaryotesEukaryotes Look at how this evolution happened!

28. chemosynthetic bacteria (extremophiles) Chemosynthesis: 0 2 + 4H 2 S + C02 CH 2 0 + 4S +3H 2 0 Stromatolites (bacteria & cyanobacteria) Oldest fossils found in western Australia and southern Africa ~ 3.5 byo Photosynthesis: 6H 2 O + 6CO 2 + nutrients + light energy C 6 H 12 O 6 + 6O 2

29. Stromatolites from Shark’s Bay Australia mostly cyano

30. Early prokaryotes may have arisen near hydrothermal vents Hydrothermal vents are rich in sulphur and iron-containing compounds needed for ATP synthesis. Temperatures can reach 120 C.

31. Hot springs in Yellowstone National Park – pigmented bacterial mats

32. 1 st dinosaur end of dinosaurs 1 st reptiles 1 st amphibians 1 st land plants 1 st fish 1 st invertebrates Millions of Years Geologic Time Scale

33. Extinctions Habitat Disruption –Volcanic Eruptions –Asteroid Impacts –Sea Level Change Habitat Modification –Climate Change –Mountain-Building –Sea Level Change –Precipitation Change –Toxic Materials “Exotic” Species Introductions –Continental Drift

34. The Big Five Ordovician-Silurian extinction - 439 million years ago, 60% extinct Late Devonian extinction - 364 million years ago, 70% extinct Permian-Triassic extinction - 251 million years ago, 90% extinct End Triassic extinction, - 199 million to 214 million years ago, 44% extinct Cretaceous-Tertiary extinction, about 65 million years ago, 85% extinct

36. Life during Ordovician 488-443 mya Graptolites, trilobites, conodonts, algae, fish, coral, crinoids, gastropods All known metazoan life confined to the seas and oceans

37. The Ordovician Extinction Event 450 Ma - 440 Ma, two bursts of extinction occurred, separated by one million years > 60% of marine invertebrates died; Gondwana moves south Sea level falls Atmospheric CO 2 drops Global cooling

38. Middle Ordovician

39. Life in Devonian 416-359 mya

40. The Devonian Period 416-359 mya Pangeae forms Extensive reef building Age of Fishes Plants & insects colonize land First vertebrates colonize land

41. The Devonian Extinction Event Possibly two to as many as seven related bursts of extinction centered on 365 Ma to 440 Ma, over as little as one half to as many as 25 million years Marine life most affected Jawed vertebrates unaffected by the loss of reefs, while agnathans in decline.

42. The Devonian Extinction Event Leading theories include changes in sea level and ocean anoxia, possibly triggered by global cooling or oceanic volcanism The widespread oceanic anoxia prohibited decay and allowed the preservation of sedimented organic matter as petroleum

43. Late Devonian / Early Carboniferous

44. Life in Permian 290-245 mya

45. The Permian Period 290-245 mya The south was cold and arid. Northern areas suffered increasingly from intense heat and great seasonal fluctuations between wet and dry conditions. Dinosaurs dominate.

46. The Permian Period The Earth's most severe mass extinction event, – 96% of all marine species –70% of terrestrial vertebrate species –mass extinction of insects –Some 57% of all families and 83% of all genera were killed recovery of life on Earth took significantly longer than other extinction events

47. The Permian Extinction Event There were from one to three distinct pulses of extinction that occurred about 245-251 million years ago Several proposed mechanisms for the extinctions: –earlier phase - gradual environmental change –latter phase - catastrophic event

48. The Permian Extinction Event Suggested mechanisms for the latter extinction pulse include: –large or multiple bolide (meteor/comet) impact events –increased volcanism and sudden release of methane clathrate from the sea floor –gradual changes include sea-level change, anoxia, increasing aridity, and a shift in ocean circulation driven by climate change –Excess CO 2 acidified oceans, contributing to the decline of shelled organisms

49. The Permian Extinction Event

50. Late Permian

51. The Triassic Period 250-200mya

52. The Triassic Period Low oxygen levels New respiratory systems developed: air sacs and diaphragms Early Triassic- high CO 2 & CH 4 Many land reptiles returned to the sea 80% of the land was arid or semiarid Late Triassic- Pangea breaks up

53. The Triassic Extinction Event The extinction occurred around 208 million years ago and happened in less than 10,000 years just before Pangaea started to break apart This extinctions struck marine life and terrestrial life profoundly At least 50% of the species now known to have been living at that time went extinct In the seas, a whole class (conodonts) and 20% of all marine families disappeared –Conodonts were early eel-like chordates

54. The Triassic Extinction Event On land, all large crurotarsans (non-dinosaurian archosaurs) other than crocodilians, some remaining therapsids, and many of the large amphibians were wiped out This event vacated terrestrial ecological niches, allowing the dinosaurs to assume the dominant roles in the Jurassic period

55. The Triassic Extinction Event Several explanations for this event have been suggested, but all have unanswered challenges: –Gradual climate change or sea- level fluctuations –Asteroid impact –Massive volcanic eruptions

56. Late Triassic / Early Jurassic

57. Late Cretaceous Extinction Event a relatively rapid extinction event dated to 65.5 million years K–T boundary a thin band of iridium-rich sedimentation found in various parts of the world

58. Late Cretaceous Extinction Event The event marks the end of the Mesozoic Era and the beginning of the Cenozoic Era Essentially all non-avian dinosaurs, mosasaurs, plesiosaurs, pterosaurs and many species of plants and invertebrates became extinct Once dinos gone, mammals dominate in next period

59. The Late Cretaceous Extinction Event The Chicxulub impact, a 10km diameter meteorite, leaving a crater ~200 Km in diameter Impact caused acid rain, ash that blocked out the sun for months, severe global cooling (nuclear winter). Increase in atmospheric CO 2, resulting in global warming, final blow to dinosaurs & many other Cretaceous species.

60. The Late Cretaceous Extinction Event Other possibility: increased volcanic activity (India’s Deccan Traps) The Deccan basalt traps of India were then antipodal to the Chicxulub impact

61. What Happened to the Dinosaurs?

62. The Late Cretaceous Extinction Event Before the end of the Cretaceous, flight evolved independently three times: –Insects, flying reptiles, birds (avian dinosaurs) By the end of the Cretaceous 65 Mya, most dinosaurs along with other large marine reptiles and various invertebrates died out No land vertebrate larger than a large dog survived the KT boundary event The angiosperm radiation was well underway during the Cretaceous, but the shift from gymnosperm to angiosperm dominated forests may have been triggered by the Late Cretaceous Extinction

63. Late Cretaceous

64. 6 th Major Extinction Golden toad 1989 Yangtze River dolphin 2006 Stellar’s sea cow 1768 Tasmanian Tiger 1936 Quagga 1883 Passenger Pigeon Martha 1914

65. Hawaiian Honey Creepers Kauai O'O (extinct); Kauai Akialoa (extinct); Kauai O'u (extinct) ; Kauai Nukupu'u (extinct); Puaioho (less than 200 left); Kamao (extinct)

66. Hawaiian Monk Seal Not Extinct California Condor Sea otter Green Turtle