Download How does evolution occur by natural selection?

Date: March 30th, 2017- period 1
Aim # 63: How does evolution occur by natural
selection?
Do Now:
Please take out last night’s homework “Phylogenetic Tree”
HW:
1)Daily Review of class notes.
2)Castle Learning due Friday
3)Quarterly Exam next Tuesday 4/4
Date: March 30th, 2017- period 5
Aim # 63: How does evolution occur by natural
selection?
Do Now:
Please take out last night’s homework “Phylogenetic Tree”
HW:
1)Daily Review of class notes.
2)Castle Learning due Friday
3)Quarterly Exam next Wednesday 4/4
Aim #63: How does evolution
occur by natural selection?
1) How Does Evolution Occur?
• EVOLUTION is a slow change in a
species over time.
• Evolution occurs by a process called
NATURAL SELECTION.
Read this cartoon, what do you think NATURAL SELECTION is?
Lamarck’s theory of Evolution
Lamarck believed that by the selective USE or
DISUSE of characteristics, organisms lost or
acquired certain traits that would be passed
on to the offspring.
2) Charles Darwin
• Considered the “father” of evolution.
• Charles Darwin traveled to the Galapagos
island, an uninhabited environment, where he
studied evolution (Darwin’s Finches)
Brain Pop: Charles Darwin
~ 4 minutes
https://www.brainpop.com/science/famoussc
ientists/charlesdarwin/
3) Natural Selection
• NATURAL
SELECTION is the
KEY to Darwin’s theory.
• According to this
theory, evolution is
controlled by NATURE.
Only the organisms that
are able to SURVIVE
and REPRODUCE will
pass on their genes.
4) Natural Selection vs.
Artificial Selection
People select the desirable
traits that will appear in the
Offspring.
Environment selects
the desirable traits
that will appear in
the offspring.
5) Conditions that are vital to
Evolution:
• Overproduction
• Variation
• Struggle For Survival
• Best Adapted To Survive
• Darwin did NOT have knowledge of the
genetic basis of inheritance
a) Overproduction
• More offspring are produced than can
survive (most die young).
Overproduction leads to
• Organisms COMPETITION!!
such as bacteria, fish, insects,
and rabbits have high reproductive rates
because the chance that their young will
survive is minimal.
b) Variation
• Variation: Individuals have differences in
their appearance, structure, or genes.
• Source of variation:
+
=
– Sexual Reproduction (sperm + egg)
– Meiosis (Independent Assortment &
Crossing Over)
– Mutation (Change in DNA)
• Mutations change the base
sequence of DNA.
• Many mutations are HARMFUL,
but some can help the organism
SURVIVE.
c) Best Adapted To Survive
• The ENVIRONMENT
chooses which traits
have adaptive value.
• An individual that has
traits favorable in a
certain environment will
live to reproduce and
pass on those traits,
others will die out.
Adaptive Value
• Adaptive Value: a change that produces a
trait that helps an organism survive.
-Example: Camouflage
• If all the members of a species were the
same then an environmental change would
wipe out the entire species. VARIATION
increases the chance that some members of
a species will survive.
d) Struggle For Survival
• “Survival of the fittest”
• Only those BEST suited will survive because
of competition for finite (limited) resources
(oxygen, water, food, and shelter)
6) Conditions that lead to
Evolution:
Activity:
• You are a naturalist who traveled to
the Galapagos Islands. The
following are excerpts from field
notes. Choose a proper heading for
each of the notes
• Use these choices: overproduction,
survival of the fittest, competition,
variation.
Overproduction
• Female finches found on the Galapagos
Islands lay enormous numbers of eggs
Competition
• These finches fight for a particular species
of insect that inhabits the small holes
found in the tree bark
Survival of the fittest
• The finches with the long beaks survive
and produce greater numbers of offspring
with long beaks
Variation
• Some finches’ beaks are long, some are
short. The finches with long beaks are
better adapted to remove the insects from
the bark.
Date: March 30th, 2017- period 1
Aim # 63: How does evolution occur by natural
selection?
Do Now:
Please take out last night’s homework “Phylogenetic Tree”
HW:
1)Daily Review of class notes.
2)Castle Learning due Friday
3)Quarterly Exam next Tuesday 4/4
Date: March 30th, 2017- period 5
Aim # 63: How does evolution occur by natural
selection?
Do Now:
Please take out last night’s homework “Phylogenetic Tree”
HW:
1)Daily Review of class notes.
2)Castle Learning due Friday
3)Quarterly Exam next Wednesday 4/4
Brain Pop: Natural Selection
~3 minutes
https://www.brainpop.com/science/cellularlif
eandgenetics/naturalselection/
7) Patterns Of Change
Species with SHORT reproductive cycles that
produce MANY offspring tend to evolve more
quickly than species with LONG life spans and
FEW offspring.
Types:
1) Gradualism – evolution occurs steadily
through time (Slow & Continuous) .
2) Punctuated Equilibrium- species stay the
same for long periods of time and then change
rapidly.
Gradualism
Punctuated
Equilibrium
8) Examples of Natural
Selection
• Industrial Melanism
• Antibiotic / Pesticide Resistance
Antibiotic Resistance
Ex: Punctuated Equlibrium
• When bacteria are exposed to an antibiotic
there is a chance that a few will have a
gene that makes them resistant.
• The bacteria WITHOUT the resistance will
be killed, while those that are RESISTANT
will survive and pass on their genes for
antibiotic resistance. The antibiotic is the selecting agent
Resistant
Bacteria
Antibiotic X
9) Why should we be concerned
about antibiotic overuse?
Why does evolution matter now?
http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html
https://www.youtube.com/watch?v=pc_Tx1h3qGc
Pesticide Resistance
Insect A- Has resistance
to A
Insect B- Has resistance
to B
Insect C- Has resistance
to C
• What would happen to
the population if
insecticide A were
sprayed on the field?
The pesticide selected
only those flies that
were resistant to
pesticide A to survive.
In other words, some
insects had a
MUTATION that
allowed them to
survive the presence of
the insecticide. These
insects were then able
to reproduce and pass
their mutation into the
next generation.
Extinction
• The disappearance of an entire species
(ex. Dinosaurs)
• It can be caused by temperature changes,
pollution, or landscape changes.
Practice
Question
a. Identify one
concept being
represented in
the cartoon.
b. Briefly explain the
concept you
identified
Time Permitting
Supplemental Information
Examples of Organisms that
are Best Adapted to Survive
A cryptic frog - This species has developed a
coloring, texture and form that are similar to the
leaves found in its environment
Disruptive Coloration
• Stripes and spots
• Helps break up an
animal's outline
• Doesn't hide
animals presencemisrepresents it
Counter Shading-Top and Bottom
Desert
horned
lizard
on a
sandy
river bed
San Diego
Katydids
Plant or Animal?... Leafy Sea
Dragon
• Chamaeleo pardalis,
a chameleon
species found in the
forests of
Madagascar
• Chameleons can
produce a wide
range of colors and
patterns on their
skin
A Von Höhnel’s chameleon turns
bark-like in Kenya.
•As the seasons change, the Arctic fox changes the
color of its coat.
•In the spring and summer, it has a dark coat, to
match the brown dirt in its environment.
•In the fall and winter, it turns white, to match the
surrounding snow.
Mimicry: monarch and
viceroy
Milk snake and coral snake
Aggressive Mimicry
• evolved devices with
which they mimic the
prey (or potential mate)
of other (usually smaller)
predators.
• They use these devices
as lures
• The angler fish
(Antennarius) displays a
lure resembling a small
fish
Warning Coloration: warns others that
they may be “unpleasant to eat”
(poisonous)
Poison
Dart
Frogs