Evolution
BIO 2215
Oklahoma City Community College
Dennis Anderson
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Evolution
• Changes in a
population over time
2
Does the idea of evolution
contradict a belief in God?
• Many scientists of all religious faiths
believe in both.
• Some people feel evolution contradicts the
literal interpretation of the Bible.
3
Earths Position in the Universe
• 400 years ago the
general public thought
that the earth was the
center of the universe
– Sun revolves around
the earth
– The earth does not
move
4
Galileo and Corpernicus
• Demonstrated scientific
evidence that the sun is at
the center of our solar
system and the earth
moves around the sun
5
Galileo and the Church
• Religious leaders felt
the heliocentric theory
(sun at the center) was
a direct contradiction
to the literal
interpretation of the
Bible
• Galileo found guilty of
heresy
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Copernican System
(Heliocentral Theory)
• Did not destroy
peoples belief in God
• Public now accepts the
overwhelming
evidence for the
heliocentric theory
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Theory of Evolution
• Science has overwhelming evidence that all life is
constantly evolving
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Charles Darwin 1809-1882
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HMS Beagle 1831-1836
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Ostrich in Africa
Rhea in
South America
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Adaptive Radiation
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Land Iquana
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Marine Iquana
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Different Tortoises on Each Island
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Origin of Species 1859
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Natural Selection
• One mechanism of evolution
• Main concepts of natural selection
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Overproduction of offspring
Inherited variation in offspring
Competition
Best adapted in a given environment survive
and reproduce to increase their kind
• They are naturally selected
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Overproduction of Offspring
• Elephants (very slow reproductive rate)
– If all the offspring of one elephant pair survive and all
their offspring survive then:
• 750 years = 19,000,000 elephants
• 1200 years = Enough elephants to cover the earth!
• Beetles
– A handful that weighs 10 mg each
– 82 weeks
• 61,000,000,000,000,000,000,000 ton
– The weight of the earth!
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Variation of Offspring
• Offspring of the same
parents are different
from each other
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Competition
• Since more individuals are born than can
survive for an extended period of time, they
compete for resources
– Food
– Living space
– Mates
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Best adapted to a given environment
are selected to survive
• Brown bears
– Adapted to survive in
Oklahoma
• Polar bears
– Adapted to survive in
Alaska
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Artificial Selection
Collie
Sheltie
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Natural
Selection of
Flies
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• Natural Selection
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Scientific Disciplines That Give
Evidence for Evolution
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•
•
•
•
Paleontology
Comparative anatomy
Biogeography
Molecular biology
Others
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Paleontology
• Study of fossils
– Allows us to see
anatomical similarities
between living species
and organisms that
lived in the past
– Allows us to see how
life has changed over
time
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Life Has Changed
• Millions of species
have been found that
are different from life
today
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Horse Evolution
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50 Million Years of Change
50 MYA
30 MYA
15 MYA
Modern
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Florida Museum of Natural History
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• Whale evolultion
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Comparative Anatomy
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Homologous Structures
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Analogous Structures
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Biogeography
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Why No Polar Bears in Antarctica or
No Penguins in Arctic?
39
Why marsupials in Australia?
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Molecular Biology
• The study of the
molecules of life
including DNA and
proteins
42
DNA Similarity
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Homeobox or HOX
• First discovered in
fruit flies in 1983
• Later found in mice,
man and other
organisms
• Controls embryonic
development of
different body regions
44
Evolution of New Body Plan
• Hox gene Ubx of
crustacean mutated in
lab
• Caused suppression of
leg development
• Mechanism for
evolution of insect
body plan 400 MYA
45
• Homeobox genes
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Comparing DNA
• Human DNA
compared to:
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Chimpanzee 99% same
Gorilla 97.7% same
Orangutan 96.3% same
Another human 99.9%
same
47
Comparing Protein Sequences
• Many proteins in all of man are identical
• Organ transplants require similar proteins in
the donor and the recipient
– A sibling or parent is often the best source for
an organ transplant
48
Which would be the closest protein
match for an organ transplant?
Assuming all are alive and healthy.
• A persons father
• A persons great grandfather
• A persons 10th great grandfather
49
Molecular Clock
• The further you go back in time, the more
proteins (and DNA) are different.
• Differences in protein sequences and DNA
can be used to estimate time when two
species shared a common ancestor
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Related Organisms
• Close similarity of protein sequences
indicates close relationship
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Cytochrome C
• Protein used to release
energy from food
• 104 amino acids
• 20 of the amino acids
occupy the same position
in all eukaryotes
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Comparison of Human Cytochrome C
• 100 amino acids different
in tuna fish
• 12 amino acids different
in a horse
• 8 amino acids different in
a kangaroo
• 1 amino acid different in
a monkey
• Identical to chimpanzee
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Pattern of Evolution Originally
Based on Fossil Record
• DNA comparisons confirm the same pattern
• Protein sequences confirm the same pattern
• 150 years of research by thousands of
scientists demonstrate beyond doubt that
life evolves.
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Speed of Evolution
• Gradualism
– Species gradually change
at a slow rate
• Punctuated Equilibrium
– Evolution occurs in
spurts followed by long
periods of stasis
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The End
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