Transcript Evolution is

Age of Earth
“Isn’t Evolution Just A Theory?
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How did the theory of Evolution come about?
• James Hutton -1785-Earth is
millions of years old.
• Thomas Malthus -1798populations outgrew their food
supplies, causing competition
between organisms and a struggle
for one species to survive against
another
• Jean-Baptiste Lamarck -1809believed that all life forms
evolved and that the driving force
of evolution was the inheritance
of acquired characteristics. He
believed that organisms changed
due to the demands of their
environment.
•1831: Charles Darwin – voyage to the Galapagos
Islands
•Lyell -1833- plant and animal species had arisen,
developed variations, and then became extinct over
time. He also believed that the Earth’s physical
landscape changed over a long period of time.
•Alfred Russel Wallace -1858-competition for
resources is the main force in natural selection
•Charles Darwin -1859- Publishes “On the Origin of
Species”
Charles Darwin
On the Galapagos Islands Darwin noticed
many variations among plants and animals
of the same general type as those in South
America. clip
Tortoises- noticed different
shaped shells which allowed for
different neck movement based
on the environment
Finches- noticed different
shapes and sizes of beaks
which fit the type of food each
bird eats
Natural Selection
Video Clip
If an organism reproduces, then the traits
of that organism are passed to the next
generation.
Traits that are favorable for a certain
environment become more prevalent within
that population.
What if the environment
changes?
The organisms must adapt to the
environment.
Those that don’t adapt-die.
This is a very slow process….does not
occur over night…many generations must
past before any change in the population
can be seen.
Example: Peppered Moth
When the trees
were normal,
the black
moths were
easily seen by
the birds, so
there were
more
peppered
moths that
survived.
When the
trees were
black, the
peppered
moths were
easily seen
by the birds,
so there were
more black
moths that
survived.
Decent with
modifications
These changes increase
a species’ fitness in
their environment.
WOLF
HUSKY
Crab Clip
Examples: The largest hog, the cow that gives
the most milk, fastest horse, domesticated dogs.
Evidence for Change Over Time
1. Fossil Record
– Fossils that show how an
organism looked millions of
years ago.
2. Geographic
Distribution
3. Comparative
Anatomy and
Embryology
4. Genetics &
Molecular Biology
How do we know
evolution is
happening? Clip
Relative Dating of fossils helps us to know
how old organisms are and when they
lived…
Embryologystudy of
early stages of
development
This may show
that organisms
had a common
ancestor.
Vestigial organs
–Organs or structures that
are no longer used by an
organism.
–They are usually reduced
in size.
Vestigial Organs
c
Speciation
•the evolution of a new species when the
genes in a population changes
Speciation Mechanisms
• Behavioral Isolation
– Populations are capable of interbreeding, but have
different courtship rituals or other type of behavior.
• Geographic Isolation
– Separated by bodies of water or mountains.
• Temporal Isolation
– Reproduction takes place at different times of the year
•Overtime they can change so much that they become
unable to breed as they adapt to their environment.
Changes in allele frequency with in a population
Divergent Evolution
Example…Adaptive
Radiation
Convergent Evolution
Coevolution
Evolution is the
______ in a
species over
_____.
Structural
Adaptation
• Change in
physical
structure or
anatomy
• EX: wings of a
seagull
Physiological
Adaptation
• Change in
internal function
or chemistry
• EX: having the
proper enzyme
to digest carbs
Behavioral
Adaptation
• Change in
behavior that
responds to
environment
• EX: lay eggs in
nests
Rates of Evolution
Gradualism
• Very gradually change, over a long time...
• Change is slow, constant, and consistent.
• Small variations that fit an organism slightly
better to its environment are selected for: a few
more individuals with more of the helpful trait
survive, and a few more with less of the helpful
trait die.
Punctuated Equilibrium
•change comes in spurts.
•There is a period of very little
change, and then one or a few
huge changes occur, often
through mutations in the genes
of a few individuals.
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LABEL each as gradualism or
punctuated equilibrium
GRADUALISM
PUNCTUATED EQ
PUNCTUATED EQ GRADUALISM
Resistance in Bacteria
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Read page p403.
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