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1. Evolution III

2. Evolution notes III
• Organic Compounds
• Three hypotheses
• 1. Extra-terrestrial Origin
• 2. Random Chance Events
• 3. Pre-biotic Evolution — most accepted idea

3. Evolution Notes III
• Earth’s age is estimated to be around
• 4.6 billion years old.
• Oldest sedimentary rocks, 3.8 billion
years contain no fossils.
• Oldest evidence is molecules of fossil
organic material, 3.4 billion
• Oldest candidate for possible organic
microfossils, 3.5 billion
• Oldest definitely living 2.5 billion—
Bluwago formation, remains of Blue-
green algae (prokaryotic cells).
• Pre-biotic evolution took approximately
one-half to a billion years

4. Evolution Notes III
Earth’s early
atmosphere
consisted of :
Carbon Dioxide Methane Gas
Nitrogen Hydrogen Sulfide
Carbon
Monoxide
Ammonia (NH3)
Water

5. Evolution Notes III
• These came from
out-gassing from
earth’s inside
• Note: there was no
free oxygen nor
ozone found in the
stratosphere
• Remember Ozone is
needed to block UV
light from the sun

6. Evolution III
Pre-biotic evolution:
• Slow evolution of chemical into
organic molecules using
external energy:
1. Heat
a. Sun
b.Internal radiation from
earth

7. Evolution Notes III
Pre-biotic
evolution:
2. Light
a. UV light
b. Visible light

8. Evolution Notes III
Pre-biotic evolution:
3. Electrical discharge
(lightning)

9. Evolution Notes III
Some Experiments:
• In 1953 Stanley
Miller mixed the
molecules of
primitive earth’s
atmosphere and
subjected them to
electrical sparks
to simulate
lightning, resulting
in the formation of
amino acids.

10. Evolution Notes III
Details of the
Miller
Experiment:
• The apparatus was
built from glass
tubes and
containers.
• Boiling water,
ammonia, methane,
and Hydrogen were
passed through an
electrical spark.
• A glass trap caught
any molecules
created by the
reaction.
• (The trap kept the
Tar 85%
Carboxlic Acids 13.0%
Glycine 1.05%
Alanine 0.85%
Glutamic Acid Trace
Glutamic Acid Trace
Aspartic Acid Trace
Valine Trace
Leucine Trace
Serine Trace
Proline Trace
Treonine Trace

11. Evolution III
In a second experiment,
hydrogen was bubbled
through the molecule mix and
let out of the flask resulting in
the formation of amino acids,
ATP, ribose and deoxyribose
sugars, urea, and other basic
building blocks of life. The
most common amino acids
that were found in this mixture
are the ones most commonly
found in living organisms
today.

12. Evolution III
In lab experiments
preformed by Sidney
Walter Fox (b. March 24,
1912. d. Aug. 10, 1998),
these amino acids
produced
thermalproteinoids under
dry and gentle forms of
heating, such as those
found in tidepools
gradually drying out.

13. Evolution Notes III
It is felt that proteins were
developed before nucleic acids.
Proteins are attracted to clay
particles.
The clay particles actually absorb the
proteins along their surface and aid in
the formation of macro –molecules.
These molecules can form into more
complex ones.
There are several different
combinations.

14. Evolution Notes III
It is felt that proteins were
developed before nucleic acids.
When DNA first appeared it could out
compete all other forms of macro-
molecules because it can replicate.
This had to happen once, because
then replication system would take
over and divergence could occur.

15. Evolution Notes III
First bacteria cells
were strictly
anaerobic, living in
carbon dioxide and
methane gasses.

16. Evolution Notes III
• Photosynthesis
first appeared in
cyanobacteria
(blue-green
algae).
• This process
began the
release of O2 into
the atmosphere
and also allowed
for more efficient

17. Evolution Notes III
• True early forms of
bacteria came about
around 2.5 million years
ago. First eukarotic
cells occurred
1,300,000,000 (1.3x109
)
years ago. Oldest
multicellular animals are
approximately one
billion to 7,000,000
years old.

18. Evolution Notes III
Hardy / Weinberg Law of Equilibrium
Determines the expected statistical results
from a mathematical equation of genes
(alleles) in a population (a group of
interbreeding species).

19. Evolution Notes III
Works only under these conditions:
1.Random and equal mating
2.Very large population size (infinite
number ∞, several 1,000s)
3.No net mutations
4.No selection (natural or artificial)
5. No gene flow (in or out of population)

20. Evolution Notes III
Equation: p2
+ 2pq + q2
= 1
Where: p = frequency of dominant
allele
q = frequency of recessive
allele
It is (p+q)2
factored

21. Evolution III
• Results in:
= p2
= 2pq
= q2

22. Evolution III
• Results in:
BB = p2
Bb = 2pq
bb = q2

23. Evolution III
Class Eye Color: p2
+ 2pq + q2
= 1
Brown — pq + p2
Blue — q2
Total
q2
= #/@
q= square root of q2
= ?
p= 1-(square root of q2
) = ?
This results in the percent of BB, Bb, and bb alleles
If you are not
brown-eye, then you
have blue eyes

24. Evolution III
Class Eye Color: p2
+ 2pq + q2
= 1
Example
11 Brown — pq + p2
6 Blue — q2
17 Total
q2
= #/@
q= square root of q2
=
p= 1-(square root of q2
) =
This results in the percent of BB, Bb, and bb alleles
.412
+ 2(.41 *.59)+ .592
.17 + 2(.24) + .35
.17 + .48 + .35
17% BB 48% Bb 35% bb
6/17 = .35
.59
1-.59=.41

25. Evolution III
Usually doesn’t happen in nature, but used
because:
1. Nature approximates these conditions
by/because
a) Most mutations cancel each other
b) Probability of selection (death) having an effect
is low
c) Some populations have little movement
2. Can use to make predictions
3. Can alter equation mathematically
4. Use as a tool to measure change

26. Evolution Notes III
Selection:
• It is the differential survival
or reproduction of
individuals of different
genotypes.
• Natural selection works
only on heritable traits —
genes.

27. Evolution Notes III
Natural Selection:
• Controlled by large numbers of genes
• Natural selection acts on phenotypes, not genotypes.
• The phenotypic trait must be heritable, however, in
order for evolution to occur.
• Natural selection acts faster against dominant alleles
than recessive alleles.
• Evolution does not produce perfectly adapted
organisms.
• Evolution generally causes the modification of
existing structures, not the creation of brand new ones
and the results are often compromises between various

28. Evolution Notes III
Three types of selection:
1. Directional — pushes values
toward one extreme
2. Normalizing — selection
against extremes (stabilizing)
3. Disruptive — two or more
favored at same time

29. Evolution Notes III
• Directional
Selection:
– Eliminates one
extreme variation
from an array of
possible
phenotypes.
Results in a shift
towards the other
extreme.

30. Evolution Notes III
• Stabilizing
Selection:
– Selection acts to
eliminate both
extremes of an array
of phenotypes.
Results in an
increase in
individuals exhibiting
an intermediate
phenotype.

31. Evolution Notes III
• Disruptive
Selection
– Selection acts to
remove the
intermediate
phenotypes
favoring the
extreme
phenotypes:

32. Evolution Notes III
Other types of selection:
1. Genetic Drift the random loss of fixing of
genes because of a small gene pool
2. Gene Flow the loss of alleles through
immigration or emigration
3. Neutral Alleles

33. Evolution Notes III
Speciation
Incomplete speciation
1. Sub-species —
interbreed
2. Semi-species —
mate less often

34. Evolution Notes III
Speciation
How speciation
occurs
1. Reproductively
Isolated
2. Evolutionally
Divergent
1. Mutations
2. Environment

35. Evolution Notes III
Classic Examples of
speciation:
1. Allopatric – geographic
a) Separate species adapt to
own area / climate
b) If they can meet and if
cannot mate then
allopatric
c) Must be separated a long
time — 10,000 to 50,00
years

36. Evolution Notes III
Examples:
1. Squirrels of the Grand Canyon were at one time the
same species
North Rim South Rim
Kaibab Albert’s
Higher elevation Lower elevation
Eats pine nuts Eats seeds
Darker fur Golden yellow fur
White tail Not white tail
• Now they are separate species

37. Evolution Notes III
1. Habitat preference — Apple Maggot
Fly originally on Hawthorne trees
2. Chromosomal Mutation
a) Different ploidy (N)
b) Extremely commonn in plants
c) Instance speciation
d) Parthoenogenetic reproduction
i. Females only, no mating, no male needed
ii. Some species of lizards in the Southwest

38. Evolution Notes III
II Parpatric — cline
• Cline —
1. Character gradient in
morphological geographic
variable sup-species
2. Continuing change from
one geographical area to
another
Examples:
1. Frogs along the Atlantic
Coast
2. Gulls around Arctic Circle
(circumpolary)

39. Evolution Notes III
III Catastropic —
environmental disaster
Isolation of small groups of
population members and to
which genetic drift occurs
Reasons:
1.Reproductive isolation
2.Divergency

40. Evolution Notes III
IV Convergent evolution:
– This occurs when species evolve
into a common phentoypic form due
to a common need.
Example the diagram portrays a shark,
icthyosaurus, and a dolphin. These are fish,
reptile ands mammal respectively (very
different families of animals). Yet they all
have a torpedo body shape, pectoral, caudal
and dorsal fins. This is based on their
common need to swim rapidly in an aquatic
environment.

41. Evolution Notes III
Divergent evolution.
• Occurs when species
evolve in several
directions away from a
common ancestor.
• This happens usually
to fill a vacant
ecological niche. Also
known as adaptive
radiation.

42. End

43. • http://www.becominghuman.org/