Download Natural Selection Lab- PhET Simulation – Keyla Putrika Pre

Natural Selection Lab- PhET
Simulation – Keyla Putrika
Pre-Lab Questions
1. What variables can you influence in this lab?
Environments, long/short teeth, long/short tail, fur color, genes.
2. Define what a genetic mutation is. How do genetic mutations happen? How often?
Genetic mutation is what makes us difference, there are two types of genetic mutation;
hereditary and somatic. We don’t know the exact time when it will happen, but we can be
sure that It will last for a long term.
3.
What do the terms fitness and adaptation mean? What is the difference between the
two?
Terms fitness is the ability for an organism to survive and reproduce in the environment,
meanwhile adaptation is like natural selection, the inherited characteristic increases the
organism’s chance or survival. The difference between them is fitness is the organisms
that survive longer will also reproduce more, but adaptation is the one that have more
beneficial characteristic will have higher chance of survival.
4.
What selection factors might effect an animal population besides the ones used in this
lab?
Artificial selection or selective breeding.
Designing The Experiment
In this Lab you will be controlling the mutations and environment of a population of rabbits. Your
will create four 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 (select a rabbit phenotype) rabbits will be (more/ less) likely to survive under
(type of selective factor) within the (select type of environment) environment, because.....
(explain how their trait will help them to survive or not)
1. I hypothesize that white fur rabbit will be more likely to survive under wolves within the
arctic environment, because white rabbit can camouflage, and brown rabbit is more
distinct compared to the white rabbit. Meanwhile, in equator environment, brown rabbit
will have more chance to survive than white rabbit.
2. I hypothesize that long teeth rabbit will be more likely to survive under food within the
equator environment, because long teeth rabbit can grab the food better, and short teeth
rabbit can’t grab the food very well.
3. I hypothesize that long tail rabbit will be more likely to survive than short tail rabbit
under wolves within the arctic environment, because long tail rabbit will be more visible
to the wolves.
***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
1
Brown
Fur
wolves
18 white
rabbit
110
white
rabbit
13 white
rabbit
5 brown
rabbit
64 white
rabbit
9 brown
rabbit
White rabbit is more
dominant than the brown
rabbit in the arctic
environment; my
hypothesize is right.
2
Teeth
food
18 short
teeth
54 short
teeth
5 long
teeth
13 short
teeth
23 long
teeth
8 short
teeth
Long teeth rabbit is
more dominant than the
short teeth rabbit under
food within equator
environment; my
hypothesize is right.
3
Tail
wolves
18 short
tail
34 short
tail
5 long tail
13 short
tail
25 long tail
101 short
tail
Short tail rabbit is more
dominant than the long
tail rabbit under wolves
within arctic
environment; my
hypothesize is wrong.
•
•
•
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?
Each rabbit have different beneficial characteristic in them, the differences make them
special in their own environment and they will have higher chance of survival and keep
producing offspring compare to the others.
2. What happens to animals that cannot compete as well with other animals in the wild?
They will die; eaten by the predators. Or they will have to move to other environment.
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 the species haven’t adapted to the new environment.
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 organisms have their own characteristic and are adapted to the
environment they’re in or the food they eat. Birds have different beaks because they are
adapting to the food they usually eat. And if all organisms are the same, it means that if
an individual gets sick, the rest of them will get it too and it can leads to extinction.
5. How do you think diseases can affect natural selection?
If an individual is immune to a disease, it means that individual will survive and keep
producing, meanwhile the ones that are not immune will die.
6.
How does this simulation mimic natural selection? In what ways does this simulation fail
to represent the process of natural selection?
The simulation shows us that there are characteristics, environment, and selective
factors, which all exist in real life natural selection. But, the amount of organisms and the
time they adapted is not the same in real life, which kind of fail to represents the process
of natural selection.
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
I
hypothesize
that
dominance white fur will
less likely to survive
under wolves within
equator environment,
because white fur rabbit
will be easier to find
than brown fur rabbit.
White
fur
rabbit
dominant.
Wolves
3 brown
rabbit
11 white
rabbit
31 brown
rabbit
5 white
rabbit
1 brown
rabbit
17 white
rabbit
0 brown
rabbit
1 white
rabbit
The brown
rabbit
population
extinct and
only 1
white
rabbit
exist.
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?
Yes, switching the alleles impact the population. Brown
rabbit has the dominant allele, which makes them have
higher chance to have offspring with its fur color. In the
end, the brown rabbit’s population increases, as the white
rabbit slowly fades away.
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? It does support my hypothesize because the dominant allele will produce
more offspring and eventually dominate the environment.
original
new
ww
WW
(brown) (white)
Ww
(white)
Brown : White Brown : White
3:1
1:3
Ww
(white)
3.
If this new experiment were to run longer would the end result be the same or different
from the original experiment?
It’s going to be different, because in the end of the new experiment, there’s only 1 white
rabbit left, and if there’s a predator, the white rabbit will get eaten and the rabbit
population will extinct.
Extension- Working with Pedigrees- Switch 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.
WW
ww
(brown) (white)
Ww
Ww
(brown) (brown)
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?
Because it shows the rabbits’ family and incest.
2.
What does it mean to have a yellow triangle above the rabbit?
It means that rabbit is a mutation
3.
What does it mean when a rabbit has a red X over it?
It means that rabbit is already dead.
4.
How accurate are the pedigrees used in this lab? Did each couple only have one baby?
It’s accurate because the pedigree shows which rabbit has the mutation and which rabbit
is already dead. Yes, each couple only have one baby.