Download Evidence for Evolution

Domain 5
Evolution
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Focus Standards
SB5. Students will evaluate the role of
natural selection in the development of the
theory of evolution.
a. Trace the history of the theory.
b. Explain the history of life in terms of
biodiversity, ancestry, and the rates of evolution.
c. Explain how fossil and biochemical evidence
support the theory.
d. Relate natural selection to changes in organisms.
e. Recognize the role of evolution to biological
resistance (pesticide and antibiotic resistance
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EVOLUTION
Evolution is the theory that
organisms change over time, a
process by which modern
organisms have descended from
ancient organisms.
History behind the theory
• Proposed by Charles Darwin (Darwinism) and
Alfred Wallace in 1858
• Earlier concepts of evolution
– Carolus Linnaeus (a Swedish botanist who laid
the foundations for the modern scheme of
nomenclature).
– Georges Louis Leclerc de Button- challenged
many of the accepted ideas of the day.
Proposed that species shared ancestors instead
of rising separately.
– Eramus Darwin- Darwin’s grandfather.
Proposed that all living things were descended
from a common ancestor and that more complex
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forms of life arose from
less complex forms.
Earlier concepts on
evolution cont.
• Jean-Baptiste Lamarck (Lamarckism)-Proposed that by
selective use or disuse of organs, organisms acquired or
lost certain traits during their lifetime. This is known as
the Inheritance of acquired traits
• Thomas Malthus (economist)- Reasoned that if the human
population continued to go unchecked, sooner or later
there would be insufficient living food and space for
everyone.
• George Cuvier- Proposed the theory of catastrophism
that natural disasters such as floods and volcanic
eruptions have happened often during Earth’s long history.
• These events shaped landforms and caused species
to become extinct in the process
Earlier concepts of evolution
cont.
• James Hutton (geologist)- Proposed that changes he
observed in landforms resulted from slow changes over a
long period of time, known as gradualism.
– Argued that the laying down of soil or the creation of
canyons by rivers cutting through rock were not the
result of large events, rather slow processes that
happened in the past.
• Charles Lyell (geologist)- Expanded Hutton’s theory of
gradualism into the theory of uniformitarianism.
Proposes that the geologic process that shapes Earth are
uniform through time.
– Observed processes that made small changes in Earth.
Darwin’s Observations
Great diversity among species

Animals were well adapted to habitat
Different species live in similar
ecosystems
Animals on the Galapagos islands varied
according to where they lived
 Tortoises
 Finches
GENETIC VARIATION
• Evolution is caused by
genetic variation.
• Genetic variation comes from
changes in DNA, which can
be caused by:
–Crossing over (occurs
during Prophase I of
meiosis I)
–The random assortment of
genes (during meiosis II)
–Mutations (in genes and
chromosomes)
–Artificial selection
–Natural selection
ARTIFICIAL SELECTION
• Artificial selection takes
place with human control or
direction.
• Examples of artificial
selection
–Selective breeding
–Genetic engineering
EXAMPLE OF
ARTIFICIAL SELECTION
• Broccoli, cabbage, kale,
cauliflower, and kohlrabi are
common vegetables that were
cultivated from forms of wild
mustard.
• This is evolution through
artificial selection.
NATURAL SELECTION
Natural selection is the
process by which organisms
that are best suited to live in
an environment survive,
passing on their genetic
traits to their offspring.
NATURAL SELECTION
• Natural selection takes place
without human control or
direction.
• Over time, natural selection
results in changes in the
characteristics of the
population.
Natural Selection vs. Artificial
Selection
• Artificial Selection- The process by which humans change
a species by breeding it for certain traits.
– Humans determine which traits are favorable and
breed individuals that show those traits.
• Natural Selection- The mechanism by which individuals
that have inherited beneficial adaptations produce more
offspring than do other individuals.
– The environment is the selective agent, therefore,
characteristics are selected only if they give
advantages to individuals in the environment as it is
right now.
Lamarck vs. Darwin
Introduction to
change in organisms
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What is a theory?
• The most probable
explanation for a large
set of data based on
the best available
evidence
• Summarizes a
hypothesis or group of
hypotheses that have
been supported with
repeated testing
What is a species?
What is a population?
• Species – group of a
single type of organisms
that interbreed and are
reproductively isolated
• White-tailed deer
• Population – refers to a
group of organisms of a
particular species living
in a certain area.
• White-tailed deer on Mt.
Nebo
Lamarck’s Theory
• Jean Baptiste Lamarck:
1800’s
– Believed:
• Change Occurs Over Time
• inheritance of acquired
characteristics
– acquired changes were passed
to offspring
• Law of Use and Disuse
– If a body part were used, it
got stronger
– If body part NOT used, it
deteriorated
• Examples: Body builders or
pierced ears
Lamarck’s Theory of
Evolution
• Giraffes all had SHORT
necks originally
• Giraffe’s Necks got LONGER
from stretching for food
• “Acquired” trait (long necks)
then passed to offspring
• Giraffe population became
long-necked
Lamarck’s Theory of
Evolution
• More examples
– Traits Acquired During Ones Lifetime
Would Be Passed To Offspring
Clipped ears and tails of dogs could be passed to offspring!
Lamarck’s Mistakes
• Was he correct??
– NO!
• Traits are passed down from one
generation to the next by GENES, not by
an individual’s life experiences or
activities
• Lamarck did NOT know how traits were
inherited (Traits are passed through
genes)
• Genes Are NOT Changed By Activities In
Life
• Change Through Mutation Occurs Before
An Organism Is Born
Voyage of the Beagle
Charles Darwin
• Born Feb. 12, 1809
• Joined Crew of HMS
Beagle, 1831
• Naturalist
• 5 Year Voyage around
world
• Astounded By Variety of
Life
Voyage of the Beagle
During His Travels, Darwin
Made Numerous Observations
And Collected Evidence That
Led Him To Propose A
Revolutionary Hypothesis About
The Way Life Changes Over
Time
Darwin’s Belief’s
• Survival of the fittest OR
natural selection
– Food and resources are
limited
• So organisms have to
COMPETE to get them
(lions fight for food,
space, mates …)
• OVER PRODUCE too many
organisms
• Not all offspring will survive
only the MOST FIT (not
always the strongest!)
What happened to the
giraffe’s?
– Survival of the fittest or natural
selection
• Natural selection said the giraffes
with short necks had less food to
eat
• Why?
– the food resources changed to leaves only
on the upper branches
• What happened?
– short necks could not reach upper
branches and did not survive (couldn’t
pass on genes)
– Long neck giraffes survived & reproduced
because they were able to reach the
food
• Evolution is
the slow, gradual change in a
population of organisms
over time…
a looooooooong time!
• When there is an unequal ability of
individuals to survive and reproduce …
• This leads to a gradual change in a
population with favorable characteristics
accumulating over generations
• Most fit “naturally” selected
• New species evolves
Natural Selection
• How does Selection occur?
– Selection of the most fit can occur
from several factors:
• Variations exist among individuals
in a population
• Competition for limited resources
• Overpopulation
• Predation/Disease
Example of Natural
Selection
• A classic example of natural
selection is the Peppered moths
during Industrial Revolution in
Europe
THE HISTORY OF
LIFE
FOSSILS
• Fossils are the mineralized
remains of animals or plants
or other artifacts such as
footprints.
• The totality of fossils and
their placement in rock
formations and sedimentary
layers (strata) is known as the
fossil record.
• The fossil record provides
evidence about the history of
life on Earth. It also shows how
different groups of organisms
have changed over time.
• The fossil record reveals that
fossils occur in a particular
order: some only in older rock
and some only in more recent
rock.
• The study of fossils is called
paleontology.
DATING FOSSILS
• Relative dating allows paleontologists to
estimate a fossil’s age compared with
that of other fossils.
• In radioactive dating, scientists
calculate the age of a sample based on
the amount of remaining radioactive
isotopes it contains.
• Scientists use the half-life of
radioactive isotopes to date fossils.
Evidence for Evolution
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Evidence
Evidence of
common
ancestry
among species
comes from
many sources.
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#1 Fossil Evidence

Fossils
o Earth is Millions of
years old!
o Fossils in older layers
are more primitive than
those in the upper
layers.
o Extinct Fossils resemble
modern animals.
o This shows a common
ancestry.
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Types of Fossils
 Permineralization
occurs when minerals
carried by water are
deposited around a
hard structure
A natural cast forms
when flowing water
removes all of the
original tissue, leaving
an impression.
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Types of Fossils
Amber-preserved fossils are
organisms that become trapped in
tree resin that hardens after the
tree is buried.
Fossilized insects
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Types of Fossils
 Impressions are imprints left in
rock
 Preserved remains form when an
entire organism becomes encased in
material such as ice, ash, tar …
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Dating Fossils
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Relative Dating of Fossils
 Estimates the time
during which an
organism lived
 It compares the
placement
of fossils in layers of
rock
 Scientists infer the
order in which species
existed
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Radiometric Dating of Fossils
 Measures the half-life of the isotope
– the time it takes for ½ of the
isotope to break down
 Carbon-12 stable; Carbon-14
radioactive (carbon in ALL organisms)
 Example:
– Carbon-14 has a half-life of 5730 years;
decays into Carbon-12
– Compare ratio of C-14 to C-12 to age
fossil
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Radiometric Dating of Fossils
 Uses Radioactive Isotopes: atoms of
the same element with differing
neutrons
 Example:
–
–
–
12C
and 14C
12C = 6 protons + 6 neutrons
14C = 6 protons + 8 neutrons
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Radiometric Dating of
Fossils
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#2 Geographical Distribution
 Geography & environment gives
evidence for evolution
 Island species most closely resemble
nearest mainland species
 Populations can show variation from
one island to another
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#3 Embryology
 Embryo (early developmental stage) gives
evidence of evolution
 Identical larvae, different adult body
forms
 Similar embryos, related but diverse
organisms
 Shows
common
Larva
ancestry
Adult crab
Adult barnacle
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#3 Embryology
Vertebrates
all share gill
slits and a
tail in their
early
embryo
stage;
Share a
common
ancestor
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#4 Comparative Anatomy
 The study of anatomy provides
evidence of evolution
 Homologous structures are
similar in structure but
different in function.
 Homologous structures ARE
EVIDENCE of a common
ancestor.
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Homologous Structures
ARM
LEG
Flipper
Wing
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#4 Comparative Anatomy
 Analogous structures are similar
in function but differ in structure
 Analogous structures DO NOT
show common ancestry
Fly wing
Bat wing
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Structural patterns are clues
to the history of a species.
Vestigial structures are remnants of
organs or structures that had a
function in an early ancestor.
Examples include ostrich wings, human
appendix, and wisdom teeth, whale
and snake pelvis/hind legs
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Pythons have tiny
femurs (leg bone)
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#5 Molecular and Genetic
Evidence
 AKA Biochemical
Evidence
 Two closely-related
organisms will have
similar DNA, RNA, and
protein (amino acid)
sequences.
 This also gives
evidence of a common
ancestor.
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Five examples of Evidence
for Evolution
1.Fossils
2.Geographical Distribution
3.Embryology
4.Comparative Anatomy
5.Molecular and Genetic
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Destruction of Natural
Enemies
Development of Resistance
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