The History of Life

1. The History of Life R. Jenkins

2. The Big Bang(Video Clip) • 12-15 billion years ago all matter was compressed into a space the size of our sun • This was followed by a Sudden instantaneous distribution of matter and energy throughout the known universe

3. Archeon Eon and Earlier (video clip- From the Big Bang) • 4.6 bya: Origin of Earth • 4.6 – 3.8 bya • Formation of Earth’s crust, atmosphere • Chemical and molecular evolution • First cells (anaerobic bacteria)

4. Earth Forms – How? • About 4.6 and 4.5 billion years ago • Minerals and ice orbiting the sun started clumping together • Heavy metals moved to Earth’s interior, lighter ones floated to surface • Produced outer crust and inner mantle

5. Earth Is “Just Right” for Life • Smaller in diameter, gravity would not be great enough to hold onto atmosphere • Closer to sun, water would have evaporated • Farther from sun, water would have been locked up as ice

6. First Atmosphere • Hydrogen gas • Nitrogen • Carbon monoxide • Carbon dioxide • No gaseous oxygen

7. Stanley Miller’s Experiment(video clip – Bill Nye) • Mixed methane, hydrogen, ammonia, and water • Simulated lightning • Amino acids and other small molecules formed gases boiling water water containing organic compounds

8. living cells enzymes and other proteins DNA RNA formation of protein–RNA systems, evolution of DNA formation of lipid spheres spontaneous formation of lipids, carbohydrates, amino acids, proteins, nucleotides under abiotic conditions Possible Sequence membrane-bound proto-cells self-replicating system enclosed in a selectively permeable, protective lipid sphere

9. Geologic Time Line Geologic Time Line – Long Version (See Word Documents)

10. The First Cells • Originated in Archeon Eon • Were prokaryotic heterotrophs • Secured energy through anaerobic pathways • No oxygen present • Relied on glycolysis and fermentation

11. Proterozoic Eon • Origin of photosynthetic eubacteria • Oxygen accumulates in atmosphere • Origin of aerobic respiration

12. Evolutionary Tree ARCHAEBACTERIAL LINEAGE ANCESTORS OF EUKARYOTES Noncyclic pathway of photosynthesis Cyclic pathway of photosynthesis ORIGIN OF PROKARYOTES Aerobic respiration 3.8 bya 3.2 bya 2.5 bya

13. Evolutionary Tree ARCHAEBACTERIA Extreme halophiles Methanogens Extreme thermophiles ORIGINS OF ANIMALS EUKARYOTES ORIGINS OF EUKARYOTES Animals Heterotrophic protistans ORIGINS OF FUNGI Fungi Photosynthetic protistans ORIGINS OF MITOCHONDRIA Plants ORIGINS OF PLANTS ORIGINS OF CHLOROPLASTS EUBACTERIA Oxygen-producing photosynthetic eubacteria Other photosynthetic eubacteria Heterotrophic and chemoautotropic eubacteria 1.2 bya 900 mya 435 mya present

14. Advantages of Organelles • Nuclear envelope may have helped to protect genes from competition with foreign DNA • ER channels may have similarly protected vital proteins

15. Theory of Endosymbiosis • Lynn Margulis • Mitochondria and chloroplasts are the descendents of free-living prokaryotic organisms • Prokaryotes were engulfed by early eukaryotes and became permanent internal symbionts

16. Endosymbiosis (one species living inside another) 1. Endosymbiosis • Eukaryotic cells evolved from prokaryotic cells 1.7 billion years ago • What are now membrane bound organelles were ingested as food or entered as parasites EVIDENCE • Present day Mitochondria & Chloroplasts have their own DNA which resembles prokaryotic DNA. • They replicate their DNA like binary fission in prokaryotes.

17. Paleozoic Era (570-240 mya) • Six periods • Cambrian • Ordovician • Silurian • Devonian • Carboniferous • Permian

18. Paleozoic Era(Video Clip – Evol. Of Complex) • By early Paleozoic, diverse organisms of all six kingdoms lived in seas • During the Silurian and Devonian, plants and animals invaded the land • Ended with the greatest known mass extinction and the formation of Pangea

19. Cambrian Period • Explosive radiation of marine organisms • Mass extinction near end of period • May have resulted from cooling of seas

20. Ordovician Period • Adaptive radiation of new reef organisms in warm, shallow seas • Increase in diversity of shelled animals • Ended with glaciation and mass extinction as Gondwana straddled South Pole

21. Silurian Period • Reef communities recover • First land plants GONDWANA

22. Silurian into Devonian

23. Devonian Period • Jawed fishes arise, diversify • Ancestors of amphibians onto land • Radiation of amphibians begins GONDWANA • Period ends with another mass extinction

24. Carboniferous Period • Sea levels swing widely • Amphibians diversify • First reptiles • Seedless vascular plants and gymnosperms thrive

25. Permian Period • Insects, amphibians, and early reptiles in swamp forests

26. Permian into Triassic • Major extinction • 95% of species are lost Pangea

27. The Mesozoic Era • Divided into three periods • Triassic • Jurassic • Cretaceous • The “Age of the Reptiles” • Major geologic event was the breakup of Pangea • http://www.enchantedlearning.com/subjects/Geologictime.html

28. Triassic Period • Seas repopulated after Permian extinction • First dinosaurs and mammals • Ends with a mass extinction A therapsid

29. Jurassic Period • Radiation of the dinosaurs • Ended with a mass extinction that ended many dinosaur lineages ichthyosaur

30. Cretaceous Period • Surviving dinosaurs diversify • Seedless plants and gymnosperms begin to decline

31. Rise of Flowering Plants angiosperms 200 150 number of genera ferns cycads 100 gymnosperms 50 ginkgo other genera 0 160 140 120 100 80 60 millions of years ago

32. K-T Asteroid Impact(Video Clip – Prol. Of species) • Theory is that an asteroid impact led to mass extinction • Iridium Cretaceous seaway land

33. Cenozoic Era • Continents collided and mountain ranges arose • Mammals underwent adaptive radiation • Tropical forests gave way to woodlands and grasslands • Most recent Ice Age occurred • Humans set stage for possible mass extinction

34. Paleocene to Eocene • Tropical forests and subtropical forests extended as climates warmed • Mammalian lineage diversified

35. Later Cenozoic • Climates became cooler and drier • Grasslands and woodlands dominated • Grazing and browsing animals thrived

36. At Present • Distribution of land masses favors high biodiversity • Tropical forests are richest ecosystems • In midst of what may be a great mass extinction • Human hunters and human activities have increased the pace of extinction

37. Video Clip – Evidence for Evolution