Name_________________________________________________________Per___________
Allele Frequencies #2
Evolution is change over time. We can use our genetics knowledge to be
more specific with our definition. Evolution is a change in allele frequency
due natural selection of a trait. The allele frequency compares the amount
of one allele in a population to another allele. We express it as a decimal
or percentage. We need to calculate the allele frequencies in several
generations and compare them. If the frequency changes, evolution has
occurred.
**Allele frequencies must always add up to 1 or 100%.
Here are your two key equations. Plug in the data from any given problem to determine whether
evolution has occurred.
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1. DRAGONS: In dragons, breathing fire (F) is dominant to being unable to breathe fire (f). There are
200 dragons in the Generation 1 population. 150 dragons are FF, 20 are Ff, and 30 are ff.
a. Calculate the frequency of the “F” allele:
b. Calculate the frequency of the “f” allele:
(Hint: It is ok to use a shortcut here).
The dragons have children, and produce Generation 2 of dragons. There are 300 dragons in the
Generation 2 population. 225 dragons are FF, 30 are Ff, and 45 are ff.
c. Calculate the frequency of the “F” allele:
d. Calculate the frequency of the “f” allele.
(Hint: It is ok to use a shortcut here).
e. Did the allele frequency change between generation 1 and generation 2?
f. Has evolution occurred between generation 1 and generation 2? Explain your answer in terms
of allele frequency.
2. ALBINISM
Albinism is an inherited (genetic) disorder that can pass from parents to
offspring. A DNA mutation causes a decrease in production of a protein called
melanin. This results in little or no color (pigment) in the skin, hair, and eyes.
This occurs in humans as well as many animals such as tigers. Albinism is
recessive. When 2 copies of the recessive allele “a” are inherited by a Tiger, it
has albinism. The tiger may have a pink nose, pink paw pads, grey skin, iceblue eyes, and white to cream-colored fur with black, grey, or chocolatecolored stripes.
a. “Normal” tigers have the genotype(s)__________________
b. Tigers with albinism have the genotype(s). ______________
c. Two tigers that are heterozygous for albinism mate and have tiger cubs. What % of their offspring
are expected to have albinism? (HINT: You may need to do a Punnett Square).
d. Tigers with albinism are expected to have (INCREASED or DECREASED) fitness?
e. A population of Tigers has 150 individuals. 50 are AA, 75 are Aa, and 25 are aa.
f. Calculate the frequency of the “A” allele:
g. Calculate the frequency of the “a” allele.
(Hint: It is ok to use a shortcut here).
The population of tigers reproduces. Generation 2 has 150 tigers. 50 are AA, 90 are Aa, and 10 are aa.
h. Calculate the frequency of the “A” allele:
j.
i. Calculate the frequency of the “a” allele.
(Hint: It is ok to use a shortcut here).
Did the allele frequency change between generation 1 and generation 2?
k. Has evolution occurred between generation 1 and generation 2? Explain your answer in terms
of allele frequency.