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Evolution
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5 Types of Evolution
• Changes in a
population over time
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Natural Selection
Mutations
Genetic Drift
Gene Flow
Nonrandom mating
Change in allele
frequency (p’s and q’s)
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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.
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Earth’s Position in the Universe
• 400 years ago the
general thought that
the earth was the
center of the universe
– Sun revolves around
the earth
– The earth does not
move
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Galileo and Corpernicus
• Demonstrated scientific
evidence that the sun is at
the center of our solar
system and the earth
moves around the sun
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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
• Proposed natural selection
• Voyage on the HMS Beagle
to collect fossils and
wildlife samples
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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 Iguana
Marine Iguana
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Different Tortoises on Each Island
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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, longest
gestation of any land animal)
– 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
(Nonrandom Mating)
Collie
Sheltie
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Evolution is Change
• Changing alleles in a population can
produce new species
• Dogs have evolved from wolves
• Man has artificially selected traits to
produce the various dog breeds
• Nature uses natural selection and other
mechanisms for evolution
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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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Comparative Anatomy
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Homologous Structures
• Same structures used for different purposes
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Homologous Structures
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Homoplasy
Analogous Structures
Similar structures due to convergent evolution
Convergent evolution- similar traits despite dissimilar lineage
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Biogeographyexplains howsimilar animals in
different geographic regions of
the world
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Why No Polar Bears in Antarctica or
No Penguins in Arctic?
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Why marsupials in Australia?
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Molecular Biology
• The study of the
molecules of life
including DNA and
proteins
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DNA Similarity
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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
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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
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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
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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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Phylogenetic systematics or
cladistics
• The reconstruction of evolutionary histories
of animals
• A type of classification
• Shared traits to represent evolutionary
changes in organisms
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Phylogenetic Tree/Cladograms
• There are three types of phylogenetic groups (clades) of animals:
• Monophyletic - A group including all the recognized descendant
species of a given ancestor.
• Paraphyletic - A group that does not include all the recognized
descendant species of a given ancestor.
• Polyphyletic - A group including some or all the descendants, but not
the common ancestor of the group.
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Cladograms continued
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Branch Order - The branching pattern shows the genealogy of the organisms.
The closer two organisms are to a branch, the closer their relationship. One
might think of a branch as the place where a gene pool is separated.
Branch Length - The length of a line on the tree represents an amount of
change. The longer the line between two organisms, the greater the difference
between them. The length of the line does not indicate a length of time, only the
degree of change.
The tip of a branch represents a group of descendent taxa (often species).
The node (branch fork) represents the common ancestor of those descendents.
The common ancestor will have shared characteristics with both branches. Two
descendants that split from the same node are called sister groups.
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The End
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