Download Examples of Spontaneous Generation

Ch.14 Origin of Life
1
Fossil Record
Earth is 4.6 Billion Years Old
Fossils In Different Layers of Rock
Showed Evidence life began 3.5 BYA
2
Aristotle (384 –322 BC)
Proposed spontaneous
generation=abiogenesis
living things can arise
from nonliving matter
3
Examples of
Spontaneous
Generation
4
Example #1
muddy soil gave rise to the
frogs
5
Example #2
mice came from the moldy
grain.
6
Example #3
sewage and garbage turned
into the rats.
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Example #4
rotting
meat
gave
rise
to
maggots
8
Disproving
Spontaneous
Generation
9
Francesco Redi (1668)
1668,
Francesco
Redi,
disproved
spontaneous
generation
10
Redi’s (1626-1697) Experiments
Evidence against spontaneous
generation:
11
Disproving
Spontaneous
Generation of
Microbes
12
Lazzaro Spallanzani’s (1765)
Boiled broth and melted
top shut.
The soups remained
clear.
Later broke seals &
soups became cloudy
13
Conclusion
Critics said
sealed vials killed
“vital force”
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Pasteur's Experiment - Step 1
S-shaped Flask
Filled with
broth
special shape to
trap dust
15
Pasteur's Experimental Results
Proved microbes only come from other
microbes (life from life) - biogenesis
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Ch. 15 Evolution
Diversity of Life
17
Definition
• Evolution is the
slow, gradual
change in a
population over
time
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Lamarck’s Theory of Evolution
Jean-Baptiste
Lamarck, 1809
“Changes Are acquired
in an organism’s
lifetime”
acquired changes were
passed to offspring
19
Lamarck’s Theory of Evolution
Idea called Law
of Use and
Disuse
If a body part
were used, it
got stronger
If body part
NOT used, its
lost
20
Lamarck’s Theory of Evolution
Clipped ears be passed to offspring!
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Charles Darwin the Naturalist
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Voyage of the Beagle
Charles Darwin
Born Feb. 12, 1809
Joined Crew of
HMS Beagle, 1831
Naturalist
5 Year Voyage
around world
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Darwin’s Voyage of Discovery
24
Darwin Left England in 1831
Darwin returned 5 years later in 1836
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The Galapagos Islands
Animals On
Islands
Unique
Tortoises
Iguanas
Finches
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The Galapagos Islands
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Darwin’s Conclusion
• Scarcity of resources
leads to struggle for
existence
• Only a fraction of
offspring survive
=Survival of the
Fittest
• Called Natural
Selection
28
Publication of “On The Origin of Species”
But He Did Not
Publish For 25
Years –
Why?
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31
32
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A Common Misconception…
35
Artificial Selection = “selective
breeding”
Examples:
Dogs
36
Artificial Selection
Examples:
Dogs
37
Artificial Selection
Examples: Crops,
Decorative Plants
38
Theory of Evolution Today
Supporting
Evidence
39
Evidence for Evolution – The Fossil Record
40
How do scientists figure out how
old something is?
Relative dating —looking at where
the rock is located.
41
How do scientists figure out how
old something is?
Radioactive dating —
measuring radioactive
decay.
42
Similarities in DNA Sequence
43
Evolution
of
pesticide
resistance
in response
to
selection
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Upsetting Genetic Equilibrium
 Natural
selection is not the only way that
allele frequencies can change from one
generation to the next.
 Genetic Drift – a random loss of alleles.
 Mutation – a new mutation can add
alleles.
 Nonrandom mating – inbreeding increases
the number of homozygous traits.
 Migration – shuffles alleles between
populations; can prevent speciation.
Genetic Drift
 smaller
the sample, the greater the
chance of deviation
 These random deviations are
called genetic drift.
 more likely in small populations.
Genetic Drift
 allele
gets lost is
due to random
chance.
 Over time, drift
tends to reduce
genetic variation
through random
loss of alleles.
Frequency CR = 0.7
Frequency CW = 0.3
Frequency CR = 0.5
Frequency CW = 0.5
 C RC R =
red
 CRCW = pink
 CWCW = white
Frequency CR = 1.0
Frequency CW = 0
The Bottleneck Effect
 Sometimes
a
catastrophic event can
severely reduce the size
of a population.
 The random assortment
of survivors may have
different allele
frequencies.
 This is a type of genetic
drift called the
bottleneck effect.
The Bottleneck Effect
 The
actions of people
sometimes cause bottlenecks in
other species.
 N. California elephant seal
population reduced to 20-100
individuals in the 1890s.
 Current population
>
30,000.
 Variation drastically reduced
– 24 genes with 1 allele.
The Founder Effect
 Founder
effect – Another type of
genetic drift occurs when a small
group of individuals becomes
separated from the population and
form a new population. The allele
frequencies in their gene pool may
be different than the original
population.
Camouflage & Mimicry
51
Homologous Structures =
Same Structure, Different
Function
52
Vestigial Organs = structure with
no function
Ex.
Appendix In Man
Legs On Skinks
53
Vestigial Structures —a body part
that is reduced in size and does not
seem to have a function.
Examples: appendix, wisdom teeth and
moving ears.
54
Embryology —study of the
development of embryos
Examples: gills
and tailbones
in humans
55
Embryonic Structures
Chicken
Turtle
Rat
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