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Evolution
Evolution
Evolution- change in
population over time
Evolution- Darwin
Darwin
 father of modern
evolutionary theory
 Galapagos Islands
 HMS Beagle
Darwin HMS Beagle
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Trip around the world
Scientists who
influenced Darwin


Lamarck- organisms
change due to the
pressures of their
environment, traits are
acquired
He proposed that by
using or not using its
body parts, an
individual tends to
develop certain
characteristics, which
it passes on to its
offspring.

Scientists who influenced
DarwinLamarck
Example:
A giraffe acquired its long neck because its ancestor
stretched higher and higher into the trees to reach
leaves, and that the animal’s increasingly lengthened
neck was passed on to its offspring.
Natural Selection

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Natural Selectionorganisms with
traits best suited to
the environment
survive
have more
offspring
Natural Selection

Example: Peppered Moths during the
Industrial Revolution
Natural
Selection
Extinction- permanent
loss of a species
5 mass extinctions
throughout history
Evidence for Evolution
1.
 2.
 3.
 4.
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 6.
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Fossils
Comparative anatomy
Comparative embryology
Biochemistry
Genetic evidence
Direct evidence
Evidence for
Evolution
1. Fossils
 mold or cast
of organism left
in rock, fossilized
bone and teeth
 life becomes
more complex
over time
 record is
incomplete
Evidence for
Evolution
 Most
complete
fossil record is
for the horse
Evidence for
Evolution
Relative dating layers in rock
bed used to
date organisms
 Deeper is
older, shallow
is younger
Evidence for Evolution

Radioisotope dating- uses half-life of
element to estimate age of organism
Carbon is
used
frequently
Evidence for Evolution
phylogenydescription of the
lines of descent of
plants and
animals as they
lived from one
to the next
(how they are related)

Evidence for Evolution
2. Comparative Anatomy- the study of the
structures of different organisms
homologous parts modified structures among
different groups of descendants
Evidence for Evolution
Comparative Anatomy
Evidence for Evolution
Comparative Anatomy
analogous partsstructures in
organisms that
have no common
origin but serve
the same function
 Example: bird’s
wing, bat’s wing
and insect’s wing

Evidence for Evolution
Comparative Anatomy

vestigial organs- organs having no
functions in the living organism
Vestigial toes in the horse
Vestigial pelvis and femur in whales
Evidence for Evolution
3. Comparative Embryology
the study of developing plants and
animals
Below is the pictures of embryos for a fish, human,
rabbit, tortoise, and chicken. Can you guess
which one is each type of organism?
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2
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4
5
Evidence for Evolution

Comparative Embryology
Here the pictures of the second set of
development is added. Can you tell now?
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2
3
4
5
Evidence for Evolution

How about now?
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2
3
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5
Evidence for Evolution
Comparative Embryology- The complete picture
Evidence for Evolution
4. Biochemistry
 comparison of DNA and proteins in
the body
 Example: comparison of
hemoglobin (blood protein) in
human, chimp, and dog. Human
and chimp hemoglobin more alike
than dog

Evidence for Evolution

The closer
related the
fewer
differences
in DNA and
proteins
Evidence for Evolution
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5. Genetic
Evidence
Mutationsmistakes in the
genetic code

Causes changes in
populations over
time
Evidence for Evolution
6. Direct Evidence
 Rapid Evolution

Strains of bacteria becoming resistant
to antibiotics
 Weeds and pesticides
 Insects and pesticide

Adaptations

Adaptation- change in a species that
makes it better suited to its
hump to store nutrition during
environment Along
trips or when food or water
Fur inside the ears to
protect inner ear from
sand
Nostrils that close to
keep sand out
Calluses on the the knees
to protect from abrasion
is scarce
Long eyelashes to
protect their eyes
from the sand when
the wind is blowing
Large feet for
standing in the
sand
Types of Adaptations
Structural
 Changes in structure or anatomy
 Example: bird’s beak or claws
 Mimicry- a harmless species
resembles a harmful one, predators
learn to avoid both species
 Camouflage- species features blend
in with the environment
Mimicry
Camouflage
Types of
Adaptations
Physiological
 Changes in chemical
makeup
 Examples:
digestion enzymes,
snake venom,
octopus ink
Types of Adaptations
Behavioral

Responses to the environment

Example: bird migration
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Mechanisms for Evolution
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Species- group of organisms that
can interbreed AND produce viable
offspring

Populations evolve NOT individuals
Origin of a
Species
Common
Misperception:
 Individuals
Evolve
Species evolve
NOT individuals
“And now there go the Wilsons!... Seems
Like everyone’s evolving except us!”
Mechanisms for Evolution

Gene pool- all the alleles
for a trait in the population
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Over time gene pools shift to
traits that are best suited to
the environment
Allelic frequency- the
percent of any specific gene
in a population
Genetic Equilibrium- when
the percentage of alleles in
a population remains stable
over time
Natural Selection acts on
variation in a population
 1.
stabilizing – favors average
individual
 2. directional – favors one
extreme variation
 3. disruptive – favors both
extremes of variation
Natural Selection acts on
variation in a population
Origin of Life on Earth
 Spontaneous
generation- nonliving materials can produce
life, life could be created out of
nothing, from the air
Disproving Spontaneous
Generation
Origin of Life
 Biogenesis-
living organisms
only come from other living
organisms
Origin of Cells
Earth approximately 4.6 billion years
old
 Beginning- earth’s atmosphere Hot,
gases like CO2 and nitrogen, little O2
 Gases helped to create the
atmosphere

Origin of Cells
3.5 to 4 billion years ago
 Organic Molecules 
Protocells 
Prokaryotic cells (heterotrophs) 
First simple autotrophs/producer 
Eukaryotic cells 
Multicellular organisms

Origin of a
Species

Speciation –
formation of a
new species,
members of
similar
populations no
longer
interbreed
Origin of a Species
Geographic Isolation
 Physical barrier divides population
 River, canyon, mtn. splits group
Two species of
squirrel split by
the Grand
Canyon
Patterns in Evolution
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Adaptive radiation – one ancestral species evolves
into a number of species to exploit a number of
habitats.
Patterns in Evolution

Divergent evolution- one species
evolves into two species with
different characteristics (get more
and more different from each other)
Patterns in Evolution

Convergent evolution – distant or
unrelated species evolve similar
characteristics to take advantage of
similar environments Example:
fish and dolphin