1. UNIT 4 EVOLUTION

2. A. THE ORIGIN OF LIFE

3. 1. The Early Earth a. the earth was formed about 4.6 billion years ago b. it was hot, volcanic and bombarded by particles & cosmic rays from space c. it took about 100 million years to settle down

4. 2. Early Life a. Factors needed for early life FACTOR What was available in the early Earth Basic organic molecules CO 2, NH 4, SO 2, CH 4 were in the atmosphere; in the lab, adding steam & a spark to these gases in a Miller-Urey apparatus will result in thermal protenoids & other molecules of life

6. FACTOR What was available in the early Earth Organizing basic organic molecules certain types of clay converts simple carbon- based molecules to complex ones at hydrothermal vents

7. Most hydrothermal vents spew out water at 400oC, very acid and full of sulphur The Lost City vents water is 28 o C  90oC and slightly alkaline with many dissolved carbonates The Lost City vent produces more organic molecules (eg. butane) that are the basis for many molecules in cells Feb. 2007

8. Energy source geothermal energy from deep sea vents; or solar energy both provide lots of energy

9. FACTORWhat was available in the early Earth Protective capsule phospholipids will spontaneously form LIPOSOMES which are double layered membranes Reproductive molecule RNA can reproduce without any enzymes because of an effect called ribozymes [DNA can only reproduce with enzymes]

10. ScienceDaily (Oct. 31, 2007) — Remarkably, a solution of highly poisonous cyanide in ammonia, frozen solid in a refrigerator for 25 years, produced adenine, a necessary component of life.

11. What was the early Earth like?

12. THREAT How early life coped by living in ocean strong UV LIGHT – no ozone water stops UV light if they avoid UV light – how do they get solar energy? use deep sea vents as source of thermal energy therefore early life has to be CHEMOAUTOTROPHIC

13. THREAT How early life coped by living in ocean EXTREME TEMPERATURES – lots of volcanoes water absorbs temperature changes although it remains at temperatures over 70 o C DESSICATION – low atmospheric pressure so air very dry water is wet

14. 4.0 by 3.0 by 2.0 by 1.0 by 0.0 the first prokaryote life forms prokaryote with internal membranes O 2 abundant in the atmosphere endosymbiotic life with mitochondria endosymbiotic life with chloroplasts multi- cellular lifeforms

15. 600 my 500 my 400 my300 my 200 my100 my 0.0 shelled invertebrates first vertebrates jawless fishes

16. 600 my 500 my 400 my300 my 200 my100 my 0.0 plants invade land arthropods invade land jawed fish in seas

17. 600 my 500 my 400 my300 my 200 my100 my 0.0 amphibians on land trees appear insects appear

18. 600 my 500 my 400 my300 my 200 my100 my 0.0 reptiles appear early dinosaurs

19. 600 my 500 my 400 my300 my 200 my100 my 0.0 early mammals first birds

20. dinosaurs disappear 600 my 500 my 400 my300 my 200 my100 my 0.0 first primates

21. WHEN ?WHAT ?WHY ? 530 million years ago trilobites, brachiopods mollusk, echinoderm change in sea level occurred at this time 4. Mass extinctions

22. WHEN ?WHAT ?WHY ? 440 million years ago trilobites, echinoderms and nautaloids sea levels rose rapidly & the beginning of the glaciation

24. 365 million years ago 70% of all species vanished mostly in the sea and lakes climate change, in this case a global cooling, was an important factor 245 million years ago 96% of all marine species were lost fluctuations in sea-level, a change in ocean salinity and volcanic activity plus climate change WHEN ?WHAT ?WHY ? 208 million years ago sponges, cephalopod, brachiopod, insects and many vertebrate groups climate change, seems to be important and, in particular, an increase in rainfall.

25. Showing the extent of ice in the most recent ice age

26. WHEN ?WHAT ?WHY ? 65 million years ago 85% of all species including all of the dinosaurs, many fish, plankton and many plants either died out completely or suffered heavy losses a giant meteorite crashing into the earth, severely disrupting the earth's ecosystem or volcanic activity, climate change, environmental pollution

27. WHEN ?WHAT ?WHY ? Next? 50% of species including all plants and animals Human induced climate change