Download Hardy-Weinberg Solutions

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Physical Anthropology
Population Genetics
Using Hardy-Weinberg to estimate allele frequencies
Hardy-Weinberg: allele occur in the frequency p2 : 2pq : q2
-remember:
p is the dominant allele frequency
q is the recessive allele frequency
p2 is the frequency of dominant homozygous people
q2 is the frequency of recessive homozygous people
pq is the frequency of heterozygous people
frequency of q is the square root of q2
frequencies of p and q must add to 1.00
method:
1) count the number of recessive homozygous people
2) divide by the total number of people
3) this gives you the frequency of q2 (express it in decimals)
4) to find q take the square root of q2
5) subtract q from 1 to get p
1. Two thousand immigrants from Normandy live on Saint Andre in the French West
Indies. You are mapping tongue curling distribution in the Caribbean and Saint Andre
interests you because 180 people in the population cannot curl their tongues. What do
you estimate the distribution of dominant and recessive genes to be?
Total population = 2000
People with recessive phenotype = 180
Now you need the frequency of homozygous recessive people (q2), so 180/2000 = .09
√q2 = q so √.09 = .03 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .03 = .07 = p, the frequency of the dominant allele
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2. The 1000 member Afti Tribe in Santorini has been preferentially mating for attached
earlobes for centuries. By 1990 the number of individuals with attached earlobes has
increased to 810. Exactly what would you estimate the frequencies of the attached and
unattached earlobe alleles to be?
Total population = 1000
People with recessive phenotype = 810
Now you need the frequency of homozygous recessive people (q2), so 810/1000 = .81
√q2 = q so √.81 = .9 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .9 = .1 = p, the frequency of the dominant allele
Hardy-Weinberg Dwarf Tribe
Imagine the excitement of the scientific community when you discover a dwarf tribe of
diminutive people (D) on a remote tropical island. There are some individuals with
normal stature (d). Of the population of 1000 on the island, 640 are real short. In your
article in The American Journal of Physical Anthropology what do you report as your
estimate of the frequencies of dominant and recessive alleles? Show all your work
clearly. (10 points)
Total population = 1000
People with recessive phenotype = 1000 – 640 = 360
Now you need the frequency of homozygous recessive people (q2), so 360/1000 = .36
√q2 = q so √.36 = .6 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .6 = .4 = p, the frequency of the dominant allele
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Hardy-Weinberg Hairy Ainu
A group of 1000 Hairy Ainu from Northern Japan decide to move to Southern
California where they can surf without worrying about typhoons. Although they are
called Hairy Ainu, only 640 of the group actually have this dominant trait. As a physical
anthropologist you are curious about how many alleles in their gene pool there are for
the dominant and recessive traits. Find out, and show your work.
Total population = 1000
People with recessive phenotype = 1000 – 640 = 360
Now you need the frequency of homozygous recessive people (q2), so 360/1000 = .36
√q2 = q so √.36 = .6 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .6 = .4 = p, the frequency of the dominant allele
Hardy-Weinberg Atlantis
As an anthropologist in search of exotic lifestyles you have just discovered an aquatic
tribe, the Thalassi, living just over the submerged site of Atlantis. This tribe has been
living seaborne for 6000 years and have developed webbed fingers (dominant) as an
adaptation to their marine existence. The Thalassi number 500, and 180 of them display
this trait. What is the distribution of dominant and recessive alleles? Show your work.
Total population = 500
People with recessive phenotype 500 - 180 = 320
Now you need the frequency of homozygous recessive people (q2), so 320/500 = .64
√q2 = q so √.64 = .8 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .8 = .2 = p, the frequency of the dominant allele
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Hardy-Weinberg Lefkoi Albinos
(Albino=recessive) The Lefkoi Island in the Aegean has an unusually high number of
albinos in the population. Out of a population of 2000 only 1020 are normal. As a
physical anthropologist you are curious about how many alleles in their gene pool there
are for the dominant and recessive traits. Find out, and show your work.
Total population = 2000
People with recessive phenotype
2000 – 1020 = 980
Now you need the frequency of homozygous recessive people (q2), so 980/2000 = .49
√q2 = q so √.49 = .7 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .7 = .3 = p, the frequency of the dominant allele
Hardy-Weinberg Sparse Body Hair
Sparse body hair=recessive) 500 members of the Malliaros population have decided to
migrate to an uninhabited island in the South Pacific. Of this founding group, 320
individuals have abundant body hair. What is the distribution of dominant and
recessive alleles? Show your work.
Total population
500
People with recessive phenotype 500 – 320 = 180
Now you need the frequency of homozygous recessive people (q2), so 180/500 = .36
√q2 = q so √.36 = .6 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .6 = .4 = p, the frequency of the dominant allele
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Hardy-Weinberg Hairy Scotsmen
A group of 1000 Scotsmen decide to move to south central Pennsylvania where they
will not have to worry about allergies to heather. 640 of the group have the dominant
trait of abundant body hair. As a physical anthropologist you are curious about how
many alleles in their gene pool there are for the dominant and recessive traits. Find out,
and show your work.
Total population = 1000
People with recessive phenotype = 1000 – 640 = 360
Now you need the frequency of homozygous recessive people (q2), so 360/1000 = .36
√q2 = q so √.36 = .6 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .6 = .4 = p, the frequency of the dominant allele
Hardy-Weinberg Headaches
As an anthropologist in search of exotic lifestyles you have just discovered the crabbiest
tribe on Earth, the Ponokefalo in Macedonia. The Ponokefalo number 500, and 180 of
them have migraine headaches (M). What is the distribution of dominant and recessive
(no migraines, m) alleles? Show your work.
Total population = 500
People with recessive phenotype
500 – 180 = 320
Now you need the frequency of homozygous recessive people (q2), so 320/500 = .64
√q2 = q so √.64 = .8 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .8 = .2 = p, the frequency of the dominant allele
Hardy-Weinberg Blue Eyes/Brown Eyes
The inhabitants of a remote mountain region in the Northern Caucasus area of the
former USSR is noted for its very high number of blue-eyed people. Of the population
of 10,000 individuals only 1,900 have brown eyes. Using Hardy-Weinberg estimate the
frequencies of dominant and recessive alleles. Show your work and LABEL IT
CLEARLY. Convince me you know what you're doing! Use the back.
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Total population = 10,000
People with recessive phenotype = 10,000 – 1, 900 = 8100
Now you need the frequency of homozygous recessive people (q2), so 8100/10000 = .81
√q2 = q so √.81 = .9 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .9 = .1 = p, the frequency of the dominant allele
Hardy-Weinberg More Migraines
Living deep in a cave, where no direct sunlight or loud noises live the Eniargim Tribe.
Many of the tribe, 3200 out of the 5000 members, suffer from migraine headaches (M)
Using Hardy-Weinberg estimate the frequencies of dominant and recessive alleles.
Show your work and LABEL IT CLEARLY. Convince me you know what you're
doing. 10 pts
Total population 5000
People with recessive phenotype 5000 – 3200 = 1800
Now you need the frequency of homozygous recessive people (q2), so 1800/5000 = .36
√q2 = q so √.36 = .6 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .6 = .4 = p, the frequency of the dominant allele
Polydactyli
The Polydactyli population is noted for the extreme frequency of six fingers (dominant).
Out of a population of 10,000 individuals, 7,500 have 6 fingers. What is the distribution
of dominant and recessive alleles in the population?
Total population
10,000
People with recessive phenotype 10,000 – 7,500 = 2500
Now you need the frequency of homozygous recessive people (q2), so 2500/10000 = .25
√q2 = q so √.25 = .5 = q, the frequency of the recessive allele
p + q = 1 so 1 – q = p
1 - .5 = .5 = p, the frequency of the dominant allele