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Natural Selection Lab- PhET Simulation
Pre-Lab Questions
1. What variables can you influence in this lab?
Colors, long/short teeth, long/short tail, environment, adding wolves and food
2.
Define what a genetic mutation is. How do genetic mutations happen? How often?
Genetic mutation is happened randomly when a factor in the dna is changed so it is
different from its parent cells.
3.
What do the terms fitness and adaptation mean? What is the difference between the
two?
Adaptation is when a species change their behavior to better suit the environment while
fitness the degree of suitability in a particular environment
4.
What selection factors might effect an animal population besides the ones used in this
lab?
Their height, behavior, and food preference
Designing The Experiment
In this Lab you will be controlling the mutations and environment of a population of rabbits. Your
will create three hypotheses and design an experiment to test each one. Your hypothesis will
follow the format where you fill in the (...) with your own ideas and reasons.
I hypothesize that brown rabbits will be more likely to survive under their brown fur
within the equator environment, because they can hide better from predators
I hypothesize long tail rabbits that will be more likely to survive under their fur within the
arctic tundra environment, because they can survive better in the cold
I hypothesize that long teeth rabbits will be more likely to survive under long teeth within
the equator environment, because they can find food better
***You must make at least one hypothesis for each of the three different types of phenotype mutations***
For each experiment you must have a control (no mutation) and fill in the following chart
Experiment
and
Hypothesis
Pheno
type
Selective
Factor
CONTROL
Group
Initial
Population
at F3
CONTROL
Group
Final
Population
Experment
Group
Initial
Population
at F3
Experiment
Group
Final
Population
Conclusion/
Observation
Brown fur
bunnies will
be more
than the
white ones.
Brow
n fur
is
domin
ant,
white
fur is
reces
sive
Brown
fur
5
2
1
70= total
bunnies
68=
brown
2= white
Brown fur bunnies
survived more than
the white ones in
the equator area
Long tail
bunnies will
have a
higher
adaptability
than short
tailed
bunnies
Long
tail is
domin
ant,
short
tail is
reces
sive
Long
tail
6
110
0
128= total
bunnies
110=
Short tail
18= Long
tail
The hypothesis is
wrong, at the end
the short tail is
more dominant
compared to the
long ones.
Long teeth
will be have
a higher
chance to
survive so
they can
find food
easily
Long
teeth
is
domin
ant,
short
teeth
is
reces
sive
Long
Teeth
5
13
1
18=Total
Bunnies
13= Short
Teeth
5= Long
Teeth
The long teeth is
more recessive
compared to the
long ones.
•
•
•
For each of the experiments, begin by adding a friend and a mutation. Wait until the F3
generation before adding the selective factor. After adding the selective factor let the
simulation run for another 3 or 4 generations.
Use the population numbers from the chart to get you numbers for the table, remember
you can zoom in and out on the chart to get more accurate reads.
Repeat for experiments 2, 3 and 4
Post-Lab Questions
1. Based upon your evidence from the simulation what conclusion are you able to make
about each of the three different types of phenotypes in rabbits?
The most significant phenotype is the fur color, since it is the main factor that helped
them hide from the predators. Hence, it is why rabbits with fur that have the same color
as the environment would survive better than those with different fur color.
2.
What happens to animals that cannot compete as well with other animals in the wild?
They will eventually die out either from lack of food or eaten by predators.
3.
Sometimes animals that are introduced into an area that they never lived in before, outcompete and endanger resident species, why do you think this happens?
Because their behavior is not yet suited for the environment so they can’t coexist with
the residential species since their behavior contradicts one another.
4.
If only one species is considered the "fittest", why do we still have so many variations
among species. Why do some birds have very long pointy beaks, while other birds have
short flat beaks?
Because each attributes only work for specific environments and is designed to help the
animals survive in that environment.
5.
How do you think diseases can affect natural selection?
Eventually, a species would develop an immunity against the disease, which helped
them survive while other species died out.
6.
How does this simulation mimic natural selection? In what ways does this simulation fail
to represent the process of natural selection?
It mimics the way a predator would prefer eating a prey that they can easily spot.
However, it fails to consider other factors such as diseases, natural disaster, and other
predators that have specific traits to help them spot their prey easier.
Extension- Changing the Dominance and
Recessive Alleles
Take one of the experiments from the lab. Recreate the same
experiment, EXCEPT when you add the mutation EDIT THE
GENES by switching the dominant and recessive allele for that
trait. Make a hypothesis, fill in the chart again and compare
the results to your initial experiment.
Experiment
and
Hypothesis
Pheno
type
Selective
Factor
CONTROL
Group
Initial
Population
at F3
CONTROL
Group
Final
Population
Experment
Group
Initial
Population
at F3
Experiment
Group
Final
Population
Conclusion/
Observation
If the brown
fur trait is
recessive,
the rabbit
population
will decline
Brow
n fur
Wolves
17
3
1
0
The brown rabbit
died because it’s
gene is recessive,
while the white
rabbit who are left
are finished by the
wolves.
1.
Did switching the alleles for dominant and recessive have any impact on the population
of rabbits? If so Why? In nothing changed Why not?
If the dominant trait is a trait that can help them survive better, then the population of
rabbit will continue to increase. However, if the trait that help them survive better is
recessive, it will be hard for them to survive.
2.
Two parent rabbits are both heterozygous for the trait. Create Punnet squares for the
original experiment and the new experiment (with the changed alleles). What are the
phenotype ratios of the Punnet squares? Does this evidence support your finding? and
how? B= Dominant b= recessive
B
b
B
Bb
Bb
b
Bb
bb
Dominant: 75%
Recessive: 25%
This evidence supports the fact that recessive genes shows up less likely than dominant
genes, hence if the adaptability trait is a recessive gene, it will show up less likely.
However, the gene would always be carried if both parents are heterozygous, increasing
the chance of an offspring to get the trait to survive.
3.
If this new experiment were to run longer would the end result be the same or different
from the original experiment?
It would end the same since if the adaptive trait is the recessive gene, the majority of the
population would still decline.
Extension- Working with PedigreesSwitch from the population chart to the pedigree
chart
Begin by adding a friend and a mutation. Wait until
the F5 generation. Copy the Pedigree for two
rabbits (described below) using the key. Assume
that male rabbits are on the left and female rabbits
are on the right.
Find these two rabbits, make sure they have at least four generations:
1. Select a rabbit that has the mutation.
2. Select a rabbit without the mutation but with parents or grandparent with the mutation.
Answer the following questions:
1. How could using a pedigree be helpful?
We can use the pedigree to know the rabbit’s ancestor to figure out where the genetic
mutation happens.
2. What does it mean to have a yellow triangle above the rabbit?
It means the rabbit is the one that started the mutation.
3. What does it mean when a rabbit has a red X over it?
That means the rabbit have the recessive gene but doesn’t show the trait.
4. How accurate are the pedigrees used in this lab? Did each couple only have one baby?
It is not really accurate since the couple only have one baby while in reality rabbits have multiple
babies.