Download Title: Sources of Genetic Variation SOLs Bio 7.b.d. Lesson

Title: Sources of Genetic Variation
SOLs
Bio 7.b.d.
Lesson Objectives
Students will understand the importance of genetic variety and evolution as genetic
change.
Resources
Project Wild-Through the Bottleneck
Materials
1. Bag of beads
2. Long-neck bottle
3. Handouts (key to genetic characteristics, environmental situations, and activity sheet)
Safety
1. Beads may present a choking hazard if students put them in their mouths
2. Enforce lab rules about not throwing materials
Engage (10 minutes)
Recap of previous lesson
Concept map using terms and ideas from last class
Explore (55 minutes)
1. Bottleneck genes (45 minutes)
a. Groups of 4 students (or partners depending on classroom)
b. Give students a copy of “key to genetic characteristics, environmental
situations, and black-footed bottle neck scenario”
c. Shake the “genes” in the bottle
d. Distribute a small handful of “genes” to each group and have students match
the bead color to the gene key
e. Students chose 3 Environmental Situation Cards randomly from deck
f. Students complete “Black-Footed Ferret Bottleneck Scenario” activity sheet
g. Based on the situation cards the students receive, have students make
predictions to what they think will happen to the populations
h. Discuss student predictions
Explain (20 minutes)
1. Go over “bottleneck genes” activity (after activity)
a. How does genetic diversity help protect a population?
b. Why might a small population be more at risk for elimination than a bigger
population?
2. Notes/Discussion
a. Mutations
b. Sexual reproduction
c. Relative frequency
d. Gradual changes
e. Phylogenetic Trees
3. New Species
a. Behavioral, temporal, and geographic isolation (brief demonstrations with
class)
b. Natural selection
Elaborate (5 minutes)
1. Phylogenetic tree practice. Students completed part of this assignment in the classroom
and at home. To be turned in next class
Evaluate
1. Answers to activity sheets
2. Participation/answers to questions
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Yellow: Camouflage
Black: Precise vision
Orange: accurate sense of smell
Pink: strong claws and forearms
Dark Blue: inclination to disperse
Green: high agility
Purple: acute hearing
Red: healthy rate of reproduction
White: strong immune system
Environmental Situations
1. Farmer has been trying to protect his
fields by exterminating prairie dogs.
Very little prey is available. Given its
genetic makeup, how would your
population survive?
3. A golden eagle hunts from high above
and will prey on available animals
such as the black-footed ferret. Does
your population have the gene for
precise vision to avoid being
captured? Given its genetic makeup,
how would your population survive?
5. Black-footed ferret kits disperse from
their home territory and are able to
establish new populations in nearby
prairie dog towns. Given its genetic
makeup, how would your population
survive?
7. A plague has hit your prairie dog
town, and most of the prairie dogs die
from the disease. How does your
black-footed ferret population adapt to
a reduction in food supply? Given its
genetic makeup, how would your
population survive?
9. Black-footed ferrets are nocturnal
creatures that leave their burrows at
night to feed. Does your ferret
population have the camouflage gene
to keep well hidden from the bobcat
hunting for its dinner? Given its
genetic make-up, how would your
population survive?
11. Fleas carrying bacteria which cause
sylvatic plague have infested your
prairie dog town. Biologists have not
yet vaccinated the black-footed ferrets
in your population? Given its genetic
makeup, how would your population
survive?
13. A new generation of captive-born
black-footed ferret kits has been
preconditioned to live in the wild and
are ready to be released at a nearby
reintroduction site. Given its genetic
makeup, how would your population
survive?
2. As a coyote silently prowls nearby,
only its odor might warn of its
presence. Does your population have
the gene for an acute sense of smell
to detect and avoid the coyote?
4. Black-footed ferrets eat prairie dogs
and use prairie dog burrows for
shelter. Does your ferret population
have the agility gene to catch an
aggressive prairie dog in its dark,
narrow, winding tunnel system?
Given its genetic makeup, how would
your population survive?
6. An interstate highway has been built
near your prairie dog town. How does
this road affect your black-footed
ferret population? Given its genetic
makeup, how would your population
survive?
8. A badger is moving quietly around
the prairie dog town. Does your
population have the gene for acute
hearing to detect and avoid the
predator? Given its genetic make-up,
how would your population survive?
10. A prairie dog colony has just been
established in a state park only a few
miles away. How does the colony
affect your populations of ferrets?
Given its genetic makeup, how would
your population survive?
12. It will be difficult for your population
to take over and adapt to prairie dog
burrows in hard soils without the
gene for strong claws and forelegs.
Given its genetic makeup, how would
your population survive?
14. Humans who are building homes
have wiped out a prairie dog town 3
miles away. The surviving blackfooted ferrets from that area are
moving into your territory. Given its
genetic makeup, how would your
population survive?
Black-Footed Ferret Bottleneck Scenario
Name of Team Members:___________________________________
On your Key to Genetic Characteristics, circle the COLORS and GENES that your
population received through the bottleneck.
1. Calculate the percentage of genetic diversity of your population
Nine genes (colors) represent 100% genetic diversity in the original population.
________genes received ÷ 9 original genes = ___________(decimal) x100=_____%
2. List the genetic characteristics (colors) that your population received through the
bottleneck
3. List the genetic characteristics that your population lost when it came through the
bottleneck (Colors not received)
4. Using the environmental situation cards you received, write a prediction about what
will happen to your population during the coming year. Is the population genetically
equipped to survive in its environment? Why? How does a high (or low) percentage
of genetic diversity affect the population’s survival? How do random changes in the
environment affect the population?
Chapter 16 Notes
1. Variation and Gene Pools
a. Gene Pool: ________ the genes present in a _______________
b. Relative frequency: ____________of times an allele occurs in a gene pool
______________ with the number of times all other alleles for the same gene
occurs.
2. Sources of Genetic Variation
Mutations
Gene Shuffling
1. Changes in DNA sequence
2. Can produce changes in
_____________
3. Can be _______________,
harmful, or ______________to an
organisms fitness or reproductive
success
1. Results from sexual reproduction
2. Can produce many different
phenotypes
3. Occurs during gamete production
and crossing over in meiosis
4. Does not affect allele frequency
5. Example: Shuffling a deck of cards:
you will always have a 4/52 chance
of drawing a 4
3. Natural Selection on Single-Gene Traits
a. Can lead to changes in allele frequencies and lead to evolution
4. Natural Selection on Polygenic Traits
a. Can affect the distribution of phenotypes in 3 ways: directional, stabilizing, or
disruptive selection
Directional Selection
This occurs when….
Stabilizing Selection
This occurs when….
Disruptive Selection
This occurs when…
Draw the picture of the
graph
Draw the picture of the
graph
Draw the picture of the
graph
5. Genetic Drift
a. In small populations, an allele can become more or less common simply by
chance
b. Individuals that carry a particular allele may leave more descendances than other
individuals just by chance and over time this can cause an allele to become more
common in a population.
c. Founder effect is when a small part of a population but somehow got separated
and inhabitated a new habitat
i. Over time, the alleles in the founding population can become more
common and have allele frequencies than those of the original species
6. Isolating Mechanisms
Behavioral
Geographic
Temporal
Occurs when 2
populations are
capable of
interbreeding but have
differences in
courtship rituals or
reproductive strategies
that involve behavior
2 populations are
separated by
geographic barriers
such as rivers,
mountains, or bodies
of water
2 or more species
reproduce at different
times.
Example:
Example:
Example: