Download Evolution

How did this happen?
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Wolf ----------------------> Poodle
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Types of Theories
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Wolf ----------------------> Poodle
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Lamarck’s Theory of Evolution
(WRONG!)
Idea called Law
of Use and
Disuse
 If a body part
were used, it got
stronger
 If body part NOT
used, it
disappeared.
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Lamarck’s Theory of Evolution

Inheritance Of Acquired Traits
 Traits
Acquired During Ones Lifetime
Would Be Passed To Offspring
Clipped ears of dogs would be passed to offspring!4
Gradualism:
Long time scale
events that
gradually create and
destroy species.
Charles Darwin
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Punctuated
Equilibrium:
Short periods of
time with “rapid”
leaps in evolution.
Usually after a
major extinction
event.
Steven Gould
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Parallel Evolution:

Different Animals
On Different
Continents But
Similar Adaptations
To Shared
Environments
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Changes in Allele Frequency
 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
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Evolution
Diversity of Life
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History of
Evolutionary Thought
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Contributor’s to Darwin’s
thinking included:
:
• John Baptiste Lamarck –
Inheritance of acquired
Characteristics and Law of Use
and Disuse
• Alfred Russel Wallace –
organisms evolved from common
ancestors
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Hutton’s Theory of Geological
Change

Changes in Earth’s
crust due to slow
continuous
processes

Ideas Known as
Uniformitism and
Gradualism based on
fossil record
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Principles of Geology

Provides evidence to support evolution
of life
 Explained Geological Processes That
Shaped The Earth
 Helped Darwin Understand Sea Shells In
The Andes Mountains At 12,000+ Feet
 Expanded Earth’s Age to billions of
years
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Charles Darwin the
Naturalist
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Charles Darwin

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Born Feb. 12, 1809
Joined Crew of HMS
Beagle, 1831
Trained in Theology
and a Naturalist
5 Year Voyage around
world
Avid Collector of Flora
& Fauna
Astounded By Variety
of Life
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HMS Beagle’s Voyage
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Galapagos Tortoises
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Darwin’s Observations
Both
Living
Organisms &
Fossils
collected
Fossils
included:
Trilobites
Giant Ground
Sloth of South
America
This species NO longer existed.
What had happened to them?
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Evidence for Evolution – The Fossil Record
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Evolution
Principles
What Pressures Cause Evolution ?
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Definition
• Evolution is
the gradual
change in a
population of
organisms
over time
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1. Overproduction:
- More offspring produced than
needed.
- Only a small fraction of offspring
survive and reproduce.
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2. Competition:
- food, water, space and mates are
limited
- Competition within the species and
with other species
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3. Variation
- There is variation
within populations.
- Individuals of a
population vary in
their genetic traits.
- No two individuals
are exactly alike.
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4. Adaptations
Because of variations some
individuals are better adapted
to survive in their environment
“Survival of the Fittest”
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Adaptations
 Those
that survive and
reproduce have the fittest
genetic variations.
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5. Natural Selection

Some genetic traits are
selected for by
environmental
conditions.
 Those selected for
survival live and pass
on their beneficial
genes.

Others die and genes
are lost.
.
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Extinctions

Some species
disappear due to
a catastrophic
event in nature
(humans,
asteroid,
earthquake…)
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6.
•
•
Speciation
Over time favorable adaptations
gradually accumulate in a species
and unfavorable ones disappear.
Eventually the accumulated changes
result in a new species.
Common Descent with
Modification
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Genes create evolution!

The mutation or
combination of alleles
has to already be there
by chance.
Populations do not decide
to adapt or mutate after
an environmental
change

Only beneficial
mutations lead to
evolution!
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What Kinds of Evidence are
Used to Study Evolution?
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Selective Breeding
 Artificial
Selection
 Selective
Breeding To Enhance
Desired Traits Among Stock or
Crops
 Dogs, horses, fruits, corn etc..
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Artificial Selection
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Wild Mustard was artificially
selected to become broccoli!
Yum!
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Natural Selection
 Cannot
Be Seen Directly
 It Can Only Be Observed As
Changes In A Population Over
Many Successive Generations
 Radiation
 Fossil
Record
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Fossil Record

Earth is Billions of
Years Old
 Fossils In Different
Layers of Rock
(sedimentary Rock
Strata) Showed
Evidence Of
Gradual Change
Over Time.
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Evidence for Evolution – The Fossil Record
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Descent With Modification
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Similarities in DNA Sequence
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Evolution
of
pesticide
resistance
in
response
to
selection
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Homologous Body Structures
Structures That Have Different
Mature Forms But Develop From The
Same Embryonic Tissues
 Strong Evidence That All FourLimbed Animals With Backbones
Descended, With Modification, From
A Common Ancestor
 Help Scientist Group Animals

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Homologous Body Structures
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Similarities In Early
Development
Embryo – early stages of vertebrate
development
 Embryonic Structures Of Different
Species Show Significant Similarities

What is similar in the next slide?
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Same stages of embryos
Which one is the Human?
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Same stages of embryos
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Human Fetus (5 weeks) with
vestigal structures.
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Chicken
Turtle
Rat
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One more time for Darwin….
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Darwin's Theory
Variation
Individual Organisms In Nature Differ
From One Another. Some Of This
Variation Is Inherited
Overproduction
Organisms In Nature Produce More
Offspring Than Can Survive, And
Many Of These Offspring Do No
Reproduce
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Darwin's Theory
Competition
More Organisms Are Produced Than
Can Survive, Members Of Each
Species Must Compete For Limited
Resources
Adaptation
Each Organism Is Unique, Each Has
Different Advantages &
Disadvantages In The Struggle For
Existence
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Darwin's Theory
Natural Selection
Individuals Best Suited To Their
Environment Survive & Reproduce
Successfully – Passing Their Traits To
Their Offspring.
Speciation
Species Change Over Time. Over Long
Periods, Natural Selection Causes
Changes That May Eventually Lead To
New Species
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Darwin's Theory
Species Alive Today Have Descended
With Modifications From Species
That Lived In The Past
All Organisms On Earth Are United Into
A Single Tree Of Life By Common
Descent
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