Download Evolution - Ardsley Schools

• Evolution
Evolution
Definition
• Evolution
– Change over time
– Individuals Do Not evolve, only populations
evolve
– Change in the frequency of alleles in a
population of time
Evidence
1. Geologic Record
•
•
Radioactive dating puts Earth at 4.5-5 Billion
years old
Fossils show evidence of change over time
(oldest fossil is of bacteria dated 3.5 BYA)
Types of Fossils
Casts or Molds in
Rock
Sedimentary Rock
best rock for fossils!
Petrification
Resin fossils
Frozen Organisms
Fossilization
Relative Dating of Fossils
• Look at Strata
• Oldest is
deepest unless
an earth quake
moved strata
Further Evidence
2. Comparative Anatomy
– Homologous vs. Analogous Structures
Evidence
3. Comparative
Embryology
Evidence
4. Comparative Cytology
– All living things made of cells
– Most organelle similar structurally and
functionally
– Note:
Prokaryotes=Unique cell wall, unique
ribosomes, no membrane bound organelles
Evidence
5. Comparative Biochemistry
– Compare proteins, DNA etc…
– Humans and Chimps have over 99% DNA
similarity
Wrong!
Evidence
6. Vestigial Structures
– Appendix
– Tail bone
– Hair on make chest?
– Wisdom teeth?
Theory of Evolution
• Lamarck
– Use and Disuse
– Inheritance of acquired characteristics
Theory of evolution
• Lamarck disproven by Weismann
Theory of Evolution
•
Charles Darwin
1.
2.
3.
4.
5.
6.
Overpopulation
Competition
Survival of fittest
Natural Selection
Reproduction
Speciation
Did NOT explain how variations arise!
Types of Natural Selection
No Selecting Pressure
Stabilizing
Selection
•Very short plants
and very tall pants
selected out
•Too short-not
enough sun
exposure
•Too tall-hit down by
wind
Types of Natural Selection
Directional
Selection
•Ex. Giraffe neck
length favored long
and not short
Disruptive Selection
•Favor extremes
•Ex. Blk, Wht, Grey
rabbits with only blk and
white rocks to hide
Darwin
• Galapagos Islands
Adaptive Radiation
•Migrate
•Adapt (Natural
Selection, Survival of
Fittest)
•Speciation
Adaptive Radiation
1. Species A migrates from the mainland to the first island.
2. Isolated from the mainland, species A evolves to species B.
3. Species B migrates to the second island.
4. Species B evolves in species C.
5. Species C recolonizes the first islands, but is now unable to reproduce
with species B.
6. Species C migrates to the third island.
7. Species C evolves into species D.
8. Species D migrates to the first and second island.
9. Species D evolves to species E.
Modern Theory of Evolution
• Darwin’s Variation and Natural Selection
• Genetic basis to variations for mutation
work done by DeVries
What can cause for
changes?
Geographic Isolation
What can cause for changes?
Reproduction/Genetic Isolation
Time frame for Evolution
• Gradualism vs. Punctuated Equilibrium
Time frame for Evolution
Types of Evolution
• Convergent
– Similar adaptations based on similar needs
– They are not evolving into 1 species
Types of Evolution
• Divergent
• Coevolution
• Parallel
Hardy-Weinberg Principle
• A population will NOT evolve if:
– Population is large
– There is no mutation in population
– There is no migration
– There is random mating
p+q=1
p2+2pq+q2=1
• They studied the frequency of alleles in a
population’s gene pool (genome=all genes in a
organism)
Origin of Life
• Spontaneous Generation
– Living things come from nonliving things
Francesco Redi disproves
Spontaneous Generation of Life
Heterotroph Hypothesis
• Primitive Earth Atmosphere
– Water vapor
– Hydrogen gas
– Ammonia (NH3)
– Methane (CH4)
No Oxygen Gas (O2)
Primitive Atmosphere
• Evidence that
volcanic eruptions
release
– CO2
– N2
– H2S
– SO2
Heterotroph Hypothesis
• World filled with energy
– Lightning
– UV Radiation
– X-rays
– Heat from lava
Heterotroph Hypothesis
• Oceans were hot and a
perfect site to cook up
things
– Enough energy for form
monomers of organic
compound
• Ex. Glucose, nucleotides,
amino acids, glycerol, fatty
acids
Proof of this step
• Stanley Miller
Alternative theory of
monomers…
• Meteorites have been found containing
water, pyrimidines, purines, sugars, amino
acids
Next Step of Heterotroph
Hypothesis
• Monomers fused to form Organic
Polymers
• Proof came from Sidney Fox experiment
Monomers to Polymers
• Hydrothermal vents
rich in Iron Nickel
• Iron Nickel can act as
a catalyst
• Hot pools evaporate
and concentrate
monomers for
enhanced collisions
Next Step
• Coacervation
– “Precursor Cells”
– Conglomeration of Polymers
Next Step
• Rise of Anaerobic Heterotrophs (Precursor
to Bacteria)
– Took in glucose
– Performed fermentation
– Produced CO2
Next Steps
• Evolution of membranes
• Evolution of DNA and RNA
• Heterotroph population explosion (-Anaerobic
Heterotrophs)
• CO2 in air
• Evolution of Photosynthetic Bacteria
(Cyanobacteria) (Anaerobic Autotrophs)
• Ozone layer forms filtering harmful UV
• O2 now in air
• Evolution of Aerobic Autotrophs and Aerobic
Heterotrophs