Download Activity 1

NATURAL SELECTION
Activity 1: Breeding Bunnies
Name: ____________________________
Date: ________________ Block: _______
In this activity, you will examine natural selection in a small population of wild rabbits. Evolution, on a
genetic level, is a change in the frequency of alleles in a population over a period of time. Breeders of
rabbits have long been familiar with a variety of genetic traits that affect the survivability of rabbits in
the wild, as well as in breeding populations. One such trait is the trait for furless rabbits (naked bunnies).
This trait was first discovered in England by W.E. Castle in 1933. The furless rabbit is rarely found in
the wild because the cold English winters are a definite selective force against it.
In this lab, the dominant allele for normal fur is represented by (F) and the recessive allele for
no fur is represented by (f). Bunnies that inherit two (F) alleles or one (F) and one (f) allele
have fur, while bunnies that inherit two (f) alleles have no fur.
Materials:
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Red beans represent the allele for fur.
White beans represent the allele for no fur.
Container representing the English countryside, where the rabbits randomly mate.
The clear petri dish is the “cemetery” where rabbits will be discarded.
Two dixie cups, labeled FF and Ff
Procedures
1. Fill in the hypothesis section of the data form and specific predictions based on that hypothesis.
2. Place the 50 red and 50 white beans (alleles) in the “English countryside” container and shake up (mate) the
rabbits.
3. Without looking at the beans, select two at a time, and record the results on the data form next to
"Generation 1."
a. For instance, if you draw one red (representing a F allele) and one white bean (representing a f allele), place
a mark in the chart under "Number of Ff individuals."
b. Continue drawing pairs of beans and recording the results in your chart until all beans have been
selected and sorted.
c. Place the "rabbits" into the appropriate cup: FF, Ff, or the cemetary if they are ff.
i. The ff bunnies are born furless and the cold weather kills them before they reach reproductive
age, so they can't pass on their genes. These bunnies are placed in the cemetary for this reason
4. Count the actual F and f alleles (beans) that were placed in each of the "furred rabbit" cups in the first round.
5. Record the number in the chart in the columns labeled "Number of F Alleles" and "Number of f Alleles."(This
time you are really counting each bean, but don't count the alleles of the ff bunnies because they are dead.)
6. Total the number of F alleles and f alleles for the first generation and record this number in the column labeled
"Total Number of Alleles."
7. Place the alleles of the surviving rabbits (which have grown, survived and reached reproductive age) back into
the “English Countryside”container and mate them again to get the next generation.
8. Repeat steps three five through seven to obtain generations two through seven on your data table.
Calculations
9. Determine the gene frequency of F and f for each generation and record them in the chart in the columns
labeled "Gene Frequency F" and "Gene Frequency f."
a. To find the gene frequency of F, divide the number of F by the total number of alleles
b. To find the gene frequency of f, divide the number of f by the total.
i. Express results in decimal form.
ii. The sum of the frequency of F and f should equal one for each generation.
10. Graph your frequencies.
a. Prepare a graph with the horizontal axis as the generation and the vertical axis as the frequency in
decimals.
b. Plot all frequencies on one graph.
11. Complete the Discussion Questions form with your group.
Pre-Lab Questions:
1. What are the two alleles for fur?
a. _____________________________________________
b. _____________________________________________
2. What are the three possible allele combinations a bunny can inherit for fur?
a.
_________
b.
_________
c.
_________
3. What do the beans represent?
a. ref beans: ____________________________________
b. white beans: ____________________________________
4. Why are furless bunnies rarely found in the wild in England?
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5. Why are the white beans picked as (ff) placed into the “cemetary”?
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6. Why are you not supposed to look at the beans while you are selecting them?
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7. How do you determine the total number of alleles for each generation?
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8. How do you determine the gene frequency for each allele?
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9. When graphing your data, what will go on the horizontal (x) axis? __________________________
10. When graphing your data, what will go on the vertical (y) axis? __________________________
Problem:
How does natural selection affect gene frequencies over several generations?
Hypothesis:
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Data & Calculations
---------------------------------A---------------------------------
----B----
----C----
-----D----(B + C)
B/D
C/D
Generation
# of FF
individuals
(2 red beans)
# of Ff
individuals
(1 white bean,
1 red bean)
# of ff
individuals
(2 white beans)
# of F # of f TOTAL
Gene
Gene
alleles alleles
# of
frequency frequency
(red
(white
alleles
of F
of f
beans)
beans)
1
2
3
4
5
6
7
Title: ____________________________________
Discussion Questions:
1. What was your original hypothesis?
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2. Based on your lab data, do you need to change your hypothesis? Explain.
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3. Compare the number of alleles for the dominant characteristic with the number of alleles for
the recessive characteristic.
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4. Compare the frequencies of the dominant allele to the frequencies of the recessive allele.
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5. In a real rabbit habitat new animals often come into the habitat (immigrate), and others leave
the area (emigrate). How many emigration and immigration affect the gene frequency of F and f
in this population of rabbits? How might you simulate this effect if you were to repeat this
activity?
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6. How are the results of this simulation an example of evolution? Is this population in HardyWeinberg equilibrium?
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