Download 2. What is Natural Selection?

Jigsaw activity:
1.How does mutation lead to Adaptation?
2.What is Natural Selection?
3.Give an example of Natural Selection.
4.What is the Theory of Evolution?
5.What evidences support Evolution?
Jig saw Activity: Adaptation, Natural Selection, and Evolution
Questions
How does mutation lead to
Adaptation?
Give an example of Natural
Selection.
What is Natural Selection?
What is the Theory of
Evolution?
What evidences support
Evolution?
Notes
Jigsaw activity:
On a piece of A3 paper, write a paragraph summary that answers your
assigned question. Be ready to present your answers to your peers.
1. How does mutation
lead to Adaptation?
3. Give
an example
of Natural
Selection.
5. What
evidences
support Evolution?
4. What
2. What
is Natural
Selection?
is the
Theory of
Evolution?
1
GENETIC VARIATION
leads to
Adaptation
Fig. 22.11. Some
spectacular
adaptations.
Adaptation
• Adaptation is a long evolutionary process
where a population becomes better suited to
its habitat.
Feature which is especially
important for an organism's
survival.
Horse’s teeth
Such adaptations are produced
by the better suited forms
reproducing more successfully,
which is natural selection.
2
Adaptation is driven
by
Natural Selection
There are 2 variations of the beetles,
green and red.
The birds prefer eating the
green beetles.
Over generations the red beetles
increase in population because they are
not eaten by the birds.
More survive to produce more offspring.
Generations later….
Over time the red beetles have
been selected over the green beetles
3
An Example of
Natural Selection
How did giraffe’s develop
their long necks?
Giraffe you tube video
Incorrect model of evolution
Change through use and disuse
Natural Selection’s Explanation
Ancestors had different
neck lengths
Through natural selection,
longer necks survived and
passed on their genes.
Eventually all giraffes had
long necks.
4
Theory of
Evolution
Evolution
• Evolution is the change in the inherited traits
(passed on from parents to offspring) of a
population over many generations. These
traits could be physical, chemical or
behavioral.
This change is caused
by mutations in the
genes.
Video Clip: http://www.youtube.com/watch?v=yVqJ_mQazik
How does Evolution Work?
Natural Selection(survival of the fittest) is simply the logical
result of four features of living systems:
VARIATION
Individuals in a
population
vary from one
another (different
genes caused by
mutations)
SELECTION
some variants reproduce more than
others
INHERITANCE
parents pass on their traits to
their offspring genetically
TIME
successful variations accumulate over
many generations
5
Evidences
supporting
Evolution
Similarities in
Genetic Code
•225 Million Years Ago the continents were together making a super continent
called Pangaea
•When the continent began to split populations were separated.
•This increased the variety of living things because they all had
to adapt to different and new environments and habitats.
ONE A
Common Ancestor
SIMILARITIES IN
STRUCTURES