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Lesson #4 Population Genetics, X2
AGRO 315 Genetics
th
Questions due Monday, February 6 , 2012
1. Monarch Butterflies live an eventful life because of their life cycle and long
annual migrations.
a. What is a population of monarchs?
b. When in their life cycle are monarchs intermating?
c. Use the monarch butterfly migration map to propose how many populations of
monarch butterflies are found in North America. Describe the populations below.
d. An entomologist develops a small radio transmitter that can be attached to an
adult monarch and does not impede their ability to fly from the Northern USA to
Mexico….and back North in the spring. How could they use these radio
transmitters to determine if the Monarchs that spend the winter in Mexico are one
population or several populations?
e. Assume that an entomologist captures some monarchs that do not have white
sections in their wings. Their wing edges are all black. They decide to do a
Family genetics study to understand the genetic control of this wing spot color
trait
Black X White
→ F1 are all Gray
Based on this result, they proposed that BB is black, WW is white and BW is
gray
The entomologist hires an undergraduate as a summer employee and they
capture, phenotype and release 1000 monarchs from three populations. They
also generate 100 offspring from crossing their gray veined F1s above.
Population
Nebraska
California
Florida
F2 from their F1
Black spots
9
90
100
19
Gray spots
180
423
0
53
White spots
811
487
900
28
e. The diagrams below were drawn to show how the B and W alleles from the
male and female gene pool come together to form offspring. The sizes of the
boxes reflect the frequency of the B and W allele in the gene pool.
Determine which diagram represents each population or the family.
Nebraska Population: _____
B
California Population: _____
B
W
B
B
W
W
#1
B
W
#2
B
W
B
BB
BW
W
BW
WW
W
B
F2 family ____
W
#3
#4
f. Label one of the diagrams above to shown how it represents the HardyWeinburg formula that is used to predict genotypes given the assumption of a
population in Hardy-Weinburg equilibrium. (p2 + 2pq + q2 )
Population
Nebraska
California
Florida
F2 from their F1
Black spots
9
90
100
19
Gray spots
180
423
0
53
White spots
811
487
900
27
g. Perform an X2 test for goodness of fit to determine if the data above for the F2
family supports the hypothesis that BB is black, WW is white and BW is Gray
h. Perform an X2 test for goodness of fit to determine if the data above for
EITHER the Nebraska or the California population supports the hypothesis that
random mating is occurring with respect to this wing spot color trait.
Frequency of the B allele __________
Freq. of W ______________
i. Propose a mating system in the Florida population that is consistent with the
wing spot trait data. Justify your choice.
j. Biologists interested in monarch butterfly populations perform experiments that
reveal more about factors in the environment that can impact monarch
populations. Match the hypothesis with the slide # from the Monarch Life slide
show on the Blackboard site.
Hypothesis #1: Monarch adults with the genotype of high fat storage
have a selective advantage in the population.
Hypothesis #2: Monarch larvae are sensitive to the Bt protein toxin in
the pollen of Bt corn plants.
Hypothesis #3: Monarch sensitive to loud noises along highways have
a selective advantage in the population.
Hypothesis #4: Monarch larvae are sensitive to a minimum dose of the
Bt protein toxin.
Hypothesis #5: Monarch larvae do not encounter the minimum dose of
the Bt protein toxin in nature.
k. Rank these alleles based on which is most likely to increase in frequency in a
Monarch population (1 is the most, 4 the least)? Justify your choices and use the
term ‘selection pressure’ in your justification.
_____ the allele of a gene encoding a gut protein in the larvae that breaks down
the Bt protein in the ‘Mexican overwintering pop.’
_____ the allele of a gene encoding a gut protein in the larvae that breaks down
the Bt protein in the ‘California overwintering pop.
_____ the allele of a gene encoding a nerve protein that makes the butterfly fly
away from highway noise
____ the allele of a gene encoding an enzyme that makes lipids that are stored
in the adult butterfly.
l. Chose the terms migration, drift and mutation for these blanks below.
__________A. A hard western wind blows in the spring and many Monarchs in
California are blown into Kansas.
__________B. A hurricane wipes out 50% of the smallest monarch population in Florida.
__________C. A random mistake in replicating a monarch larvae’s gene encoding a
digestive protein is passed on and the larvae that inherit this new trait do not get sick
from the Bt protein.
2. Refer to the ABO blood group population table.
a. What is the frequency of the O allele in the Aborigine population?
b. What alleles are present in the Blackfoot population? __O
__A __B
c. The best explanation for the ABO type distribution observed among the
Sudanese population is that in Sudan there is what type of mating system?
____ random mating
____ positive assortive mating ___ inbreeding
The pedigree below shows the inheritance of the A,B,O blood groups in a human family.
Phenotype Genotype
A
B
C DE F G H I J
?
type A
AA, AO
type B
BB, BO
type AB
AB
type O
OO
K
L
D. Assume that ‘J’ marries a man who is a member of the Navajo population.
The husband does not know their blood type. This population is randomly mating
with respect to the ABO type. What is the probability that the first child of ‘J’ and
her husband will be type O?
3. We have collected the following data on tongue rolling phenotypes.
36 rollers
4 nonrollers
Assume that tongue rolling people are RR or Rr and non rollers are rr.
a. What mating system do you hypothesize for the Nebraska population with
respect to the tongue rolling trait.
_____ random mating
____ positive assortive mating
b. Given your mating system choice,
calculate the frequency of the R and r allele.
_____ R
____r
4. A population of Nebraskans is sampled and scored for their ear lobe
phenotype on March 7, 2011. The following data are collected.
FF Floppy ear lobed 10
AF Intermediate ear lobed 24
AA Attached ear lobed 6
A allele frequency ______
F allele frequency
Determine if this population is randomly mating with respect to this ear lobe trait.
Ear type
observed
expected
Dev.
Dev. 2/Exp
X2
4. Read the article “Running Blind” in PASSeL and sent to your inboxes.
Researchers have determined that the form of blindness seen in the Chloride
Springs herd is recessive. Explain why they are so concerned about the
extinction of this herd with only a small percentage (~5-15%) of the horses
suffering from cataracts.
Describe the mating system for these horses (random mating, positive assortive
mating, negative assortive mating, inbreeding?).
A trait like blindness is an evolutionary detriment to a horse, making them more
susceptible to predators and injury. Explain why the blind horses of this herd do
not die before reaching reproductive age. (Multiple reasons are given in the
article and are acceptable.)
Explain why only removing or gelding the blind horses from the herd is not
enough to eradicate the trait?
The article mentions that two dwarf horses were also found in the Chloride
Springs herd. If this is also a simple recessive trait (ie only linked to one gene),
and the herd is randomly mating amongst themselves (assume Hardy Weinberg
equilibrium), what is the frequency of the dwarf allele, little ‘d?’ Assume 90
horses in the herd. What would you expect the frequency of heterozygous horses
to be (for the dwarf allele)?