course web site
TRANSCRIPT
Course web site
www.clas.ufl.edu/users/mcmack/2008
Module 1: Evolution
Month Day TopicAug 28 History of life on Earth
30 Timeline construction
Sept 1 Theory of evolution
4 Holiday
6 Evidence for evolution
8 Mechanisms of evolution I
11 Mechanisms of evolution II
13 Speciation
Outline
1. What is life?
2. How might it have arisen?
3. What has happened since then?
Time
Cosmological
Geological
Evolutionary
Ecological
Physiological
4.5 billion years ago, the earth was born
Life is...what?
Life shares...
1. Chemical composition – CHON(SP)CarbonHydrogenOxygenNitrogen
SulfurPhosphorus
Iron, Zinc, Calcium, Sodium...
Life shares...
2. Biochemistry in liquid water– Proteins– Lipids– Carbohydrates– Nucleic acids
Life shares...
3. Use of matter and energy– Energy stored and released by breaking
chemical bonds– Autotrophs– Heterotrophs– Metabolism– Enzymes– Homeostasis
Life shares...
4. Cells– Membranes– Cytoplasm– Organelles– Nucleus
A prokaryote cell...
Life shares...
5. Reproduction– Heredity– Variation
Life shares...
6. Ecology!!!!!
Life shares...
1. Chemical composition-CHON(SP)
2. Biochemistry
3. Use of matter and energy
4. Cells
5. Reproduction
6. Ecology
How did life start?
Causal mechanism
The biogenesis paradox
Life arises from life...
But what about the first organisms?
How did life start?
• In a very different earth environment– Reducing atmosphere—No O2!
– Lots of H2O
– Lightening, volcanoes, ultraviolet rays
The primordial soup hypothesis
1. Abiotic synthesis of simple organic molecules
The primordial soup hypothesis
1. Abiotic synthesis of simple organic molecules
2. ...complex organic molecules
The primordial soup hypothesis
1. Abiotic synthesis of simple organic molecules
2. ...complex organic molecules
3. Origin of self-replicating molecules
The primordial soup hypothesis
1. Abiotic synthesis of simple organic molecules
2. ...complex organic molecules
3. Origin of self-replicating molecules
4. Formation of pre-cells
The big leap
From pre-cells to life...
Lots of time for natural selection
Life first appears in the fossil record about 3.8 billion years ago
Changes on Earth that have shaped life…
• Atmosphere (O2, UV)
• Continental drift
• Climate
• Volcanoes
• Extraterrestrial bombardment
History has been punctuated by mass extinctions
1st mass extinction 440 mya: ~75% of species disappearSudden global cooling?
Predatory arthropod
2nd mass extinction 370 mya: ~75% of species disappearContinental collision or global climate change?
3rd mass extinction 245 mya: ~96% of species disappearThe greatest event of all time!
Extraterrestrial impact?
4th mass extinction 210 mya: ~65% of species5th mass extinction 65 mya: ~76% of speciesExtraterrestrial impact or volcanism?
The 6th mass extinction ...
• Last 10,000 years– 30% of earth’s species gone by year 2100