Transcript Natural Selection ppt

Activating Strategy
Watch the short video clip below
[32 seconds]
https://www.youtube.com/watch?v=Z
9tcB-dyrF4
Does the video illustrate how
evolution or changes in
organisms occur?
Essential Question:
How does natural selection
affect the evolution of
species on earth?
Standards:
S7L5a. Explain that physical characteristics of
organisms have changed over successive
generations (e.g. Darwin’s finches and peppered
moths of Manchester).
S7L5b. Describe ways in which species on earth
have evolved due to natural selection.
Use the
Natural
Selection
Notes sheet
to record
information
In the previous activities, you
learned about evidence to support
the theory of evolution.
What is evolution?
Evolution is the process through
which species change over time.
Turn to a partner and discuss some of
the evidence that supports the theory
of evolution.
The basis for
the theory
of evolution
came from
observations by
Charles Darwin.
Darwin’s observations were made
when he visited the Galapagos Islands,
a chain of volcanic islands off the
South American coast.
One of Darwin’s most famous observations
involved Finches, a type of bird.
Watch the video clip below of finches on
the Galapagos Islands. Write down
observations you make about the finches
such as size, type of beak, what they eat,
where they live, etc.
https://www.youtube.com/watch?v=9uZGSuOxFVM
Share your observations with a partner
and be prepared to share your
observations with the class.
Darwin observed many similarlooking birds with very different
beaks. But how since they are were
on an island?
Darwin’s observations made him
wonder if the finches had evolved
from similar species.
After years of analyzing his observations,
Darwin proposed that the birds were closely
related finch species that were suited to
different environments.
Darwin proposed that
evolution could be explained
through a process he called
natural selection.
Natural Selection
A process through which species
that are best suited to their
environment survive and
reproduce at a higher rate than
other members of the species.
Natural Selection
Natural Selection Practice
One of the key ideas of
natural selection is
variation among species.
Within a
species there
are natural
differences, or
variations, in
traits.
Look at the images of the
butterflies above. What causes
these variations?
Many of the differences
among individuals results from
differences in the genetic
material of organisms.
Which organisms can have a
greater variation in genetic
material? Why?
Those who reproduce sexually
have greater variation in
genetic material because the
organism receives genetic
material from both parents.
Natural Selection and
Genetic Variation
Successive Generations
Sometimes the genetic
material itself within
organisms changes, causing a
new variation (mutation).
What serious illness currently in
the news has underwent a
mutation? How has it affected us?
The Flu. The Flu shot is not as
effective this year because the
flu virus mutated; therefore, the
vaccine does not cover all
strands of the virus.
Look at the
example to
the right of
how the
Avian Flu
mutated a few
years ago.
Sometimes the
environment
contributes to
genetic variation
such as the
diagram to the
right shows.
Genetic variations are passed on
from generation to generation
(successive generations).
Pesticide
Activity
With a partner, discuss what is
meant by the image below and
explain why it does not happen
this way.
Activities for Natural Selection
• Modeling Natural Selection
• Natural Selection Activity
• Breeding Bunnies
• Which Beak is Best?
An adaptation is any inherited
trait that gives an organism an
advantage in its particular
environment.
Turn to an elbow partner and
identify a few examples of an
adaptation in organisms.
Candy
Adaptation
[see resources]
Camouflage
Camouflage is a
type of
adaptation in
which organisms
appear to “blend”
into their
environment.
How does camouflage help
an organism survive?
Where Am I?
Where Am I?
Where Am I?
Hidden Organism
Activity
Mimicry
An adaptation
where an animal or
plant resembles
another creature or
inanimate object,
either for defense
or to gain other
advantages.
This is really a
caterpillar
The King Snake resembles the
Coral Snake so that predators
will think it is poisonous.
Which one is using
Mimicry? How do you
know?
Did the King Snake and the
Viceroy Butterfly decide to
mimic the more dangerous
animals?
NO
Turn to a seat partner and
discuss how the King Snake and
Viceroy Butterfly came to mimic
the more dangerous animals.
Organisms do not “decide” or
make a decision to evolve.
The process of natural selection
allows for organisms with more
desirable traits to survive,
reproduce, and pass the desired
traits to their offspring over
successive generations.
Camouflage and
Mimicry
https://www.youtube.com/watch?v=EJGtNigCu8&list=PLMYb_qWwxCko5ABXT1cGi
QOUzfe1XJyXv&index=4
http://ngm.nationalgeographic.com/2009/08
/mimicry/ziegler-photography
Venom is another adaptation
that has evolved over time.
Over time, venom in snakes
has evolved through natural
selection to be more effective.
Songs and Videos about Evolution and
Natural Selection [select one or two]:
• Adaptation:
https://www.youtube.com/watch?v=0N0wVq4nUBU
• Charles Darwin and Natural Selection:
https://www.youtube.com/watch?v=40U9Uv9iNI4
• Mr. Durand’s Natural Selection Song:
https://www.youtube.com/watch?v=a16OVnQEU-0
• Mr. Parr’s Evolution Song:
https://www.youtube.com/watch?v=r5Y_ILQB-Kg
Influence of Humans on
Evolution:
Complete one of the Peppered
Moths of Manchester Activities
https://www.youtube.com/watch?v=LyRA807djLcc
https://www.youtube.com/watch?v=T9MCqIV1Olk
Natural Selection Summarizer