Date: ______________________
Name: _______________________________
Practice – Calculating Allele Frequency
In an initial population of 450 mice living in a field, 130 are homozygous dominant with light brown fur, 240
are heterozygous and 80 are homozygous recessive with grey fur.
A small volcanic explosion covers some of the field with lava. Ten years later, the mice are sampled again and
120 are found to be homozygous dominant, 115 are found to be heterozygous and 110 are found to be
homozygous recessive.
a. calculate the allele frequencies of both populations. Circle your final answers. If I cannot easily
identify them, than you will get no marks.
b. Why is this microevolution rather than macroevolution?
c. If microevolution did occur, explain what might have caused it (Hint: it is ONE of the HardyWeinberg Principle categories).
Date: ______________________
Name: _______________________________
ANSWERS Practice – Calculating Allele Frequency
In an initial population of 450 mice living in a field, 130 are homozygous dominant with light brown fur, 240
are heterozygous and 80 are homozygous recessive with grey fur.
A small volcanic explosion covers some of the field with lava. Ten years later, the mice are sampled again and
120 are found to be homozygous dominant, 115 are found to be heterozygous and 110 are found to be
homozygous recessive.
a. calculate the allele frequencies of both populations. Circle your final answers. If I cannot easily
identify them, than you will get no marks.
BEFORE VOLCANO
Genotypes
Bb
BB
130
240
Bb
80
Allele Frequencies
B
[(130 x 2) + 240]/900
=0.56
b
0.44
After volcano
BB
120
Genotypes
Bb
115
Allele Frequencies
Bb
110
B
0.51
b
0.49
b. Why is this microevolution rather than macroevolution?
Answer: Will not result in a different species.
c. If microevolution did occur, explain what might have caused it (Hint: it is ONE of the HardyWeinberg Principle categories).
ANSWER: Bottleneck effect: small population
Date: ______________________
Name: _______________________________
Practice VERSION TWO – Calculating Allele Frequency
In an initial population of 250 mice living in a field, 120 are homozygous dominant with light brown fur, 90 are
heterozygous and 40 are homozygous recessive with grey fur.
A small volcanic explosion covers some of the field with lava. Ten years later, the mice are sampled again and
80 are found to be homozygous dominant, 100 are found to be heterozygous and 70 are found to be
homozygous recessive.
a. calculate the allele frequencies of both populations. Circle your final answers. If I cannot
easily identify them, than you will get no marks.
b. Why is this microevolution rather than macroevolution?
c. If microevolution did occur, explain what might have caused it (Hint: it is ONE of the
Hardy-Weinberg Principle categories).
Date: ______________________
Name: _______________________________
ANSWERS - Practice VERSION TWO – Calculating Allele Frequency
In an initial population of 250 mice living in a field, 120 are homozygous dominant with light brown fur, 90 are
heterozygous and 40 are homozygous recessive with grey fur.
A small volcanic explosion covers some of the field with lava. Ten years later, the mice are sampled again and
80 are found to be homozygous dominant, 100 are found to be heterozygous and 70 are found to be
homozygous recessive.
a. calculate the allele frequencies of both populations. Circle your final answers. If I cannot
easily identify them, than you will get no marks.
BEFORE VOLCANO
BB
120
Genotypes
Bb
90
Bb
40
Allele Frequencies
B
[(120 x 2) + 90]/500
=0.66
b
0.34
After volcano
BB
80
Genotypes
Bb
100
Allele Frequencies
Bb
70
B
0.52
b
0.48
b. Why is this microevolution rather than macroevolution?
c. If microevolution did occur, explain what might have caused it (Hint: it is ONE of the
Hardy-Weinberg Principle categories).