1. UNIT 2
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. a. Factors needed for early life
What was available in the early Earth
Basic organic molecules
CO2, NH4, SO2, CH4 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. What was available in the early Earth FACTOR
Organizing basic organic molecules
certain types of clay converts simple carbon-based molecules to complex ones at hydrothermal vents

7. Feb. 2007
Most hydrothermal vents spew out water at 400oC, very acid and full of sulphur
The Lost City vents water is 28oC  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

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

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

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. How early life coped by living in ocean
THREAT
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. How early life coped by living in ocean
THREAT
How early life coped by living in ocean
EXTREME TEMPERATURES – lots of volcanoes
water absorbs temperature changes although it remains at temperatures over 70oC
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
O2 abundant in the atmosphere
endosymbiotic life with mitochondria
multi-cellular lifeforms
endosymbiotic life with chloroplasts

15. 600 my
500 my
400 my
300 my
200 my
100 my
0.0
shelled invertebrates
first vertebrates
jawless fishes

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

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

18. early dinosaurs reptiles appear 600 my 500 my 400 my 300 my 200 my
0.0
reptiles appear
early dinosaurs

19. 600 my
500 my
400 my
300 my
200 my
100 my
0.0
first birds
early mammals

20. dinosaurs disappear first primates 600 my 500 my 400 my 300 my 200 my
0.0
first primates
dinosaurs disappear

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

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

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

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

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

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