MBG 3060 QUESTIONS AND ANSWERS
The response to selection calculation assumes several things. Which of the following
options is the most correct?
1) The generations are discrete.
2) Selected individuals randomly mate.
3) There are an equal number of males and females, pairwise mating.
4) All three of the above are correct.
5) Two out of the first three options are correct. - Answers - 4)
The degree of response to selection is a function of the superiority of the selected group
and the heritability of the trait. If we want to improve selection response, we can do what
to the superiority of the selected group?
1) Maintain the size of the selected group to prevent inbreeding.
2) Decrease the size of the selected group while increasing the difference between the
selected group and the rest of the population.
3) Increase the size of the selected group by including more individuals from the general
distribution of the population. - Answers - 2)
Selection response depends upon how well you pick animals and how heritable the trait
is. Heritability is often considered to be fixed so improving selection response normally
focuses on selecting. However, if you wanted to look at heritability as a source of more
selection response which of the following is more correct?
1) Although σA2 remains fairly constant, h2 can be improved by reducing σE2 through
more precise measurements or greater quality control.
2) σA2 remains fairly constant, h2 must also stay fairly constant as a result. - Answers -
1)
In addition to selection differential and heritability, time can also be a factor in selection
response. We can improve response in a fixed time by ...
1) Not worrying about it. The generation interval for a species is constrained by the
biology of the species and there isn't much that can be done about it.
, 2) Selecting animals sooner in life and randomly mating them sooner to produce the
newer generations sooner.
3) Selecting animals later in life so they are more stable members of the population and
more likely to contribute better progeny. - Answers - 2)
When making selection decisions, the size of the selected group can affect the potential
for accumulating inbreeding. To avoid inbreeding and improve selection response even
with a small selected group, one of these options would work better than the others...
1) Select the best and smallest selected group you can get away with, mate the best to
the best and avoid matings between relatives within this small group.
2) Select the best and smallest selected group you can get away with and avoid
matings between relatives within this small group.
3) Avoid selecting any relatives so random mating cannot possibly result in an increase
in inbreeding. - Answers - 1)
Among the 3 cases of ANOVA for calculating heritability there are 5 different ways to
compute heritability. The ranking is determined by how close the calculation matches
heritability. Any ties in ranking can be decided by considering the amount of information
used in the calculation (more is better). Rank the 5 different ways of calculating
heritability from best (1) to worst (5) using the matching system below.
1) Case 3 Sires and Dams h2 = 2(σs2 + σdams2) / σP2
2) Case 3 Dams h2=4σdams2/σP2
3) Case 1 Sires h2=4σs2/σP2
4) Case 2 Sires h2=2σs2/σP2
5) Case 3 Sires h2 = 4σs2 / σP2 - Answers - 1. 5)
2. 3)
3. 1)
4. 4)
5. 2)
Match the following three different types of selection to the model that is used to predict
or describe the selection response you would achieve with that type of selection.
1. Finite locus model
2. Infinitesimal model
3. Hybrid model
a) R = Sh2
b) BV(FF) = 2α1
c) R = 2α1 + Sh2 - Answers - 1. b)
2. a)
The response to selection calculation assumes several things. Which of the following
options is the most correct?
1) The generations are discrete.
2) Selected individuals randomly mate.
3) There are an equal number of males and females, pairwise mating.
4) All three of the above are correct.
5) Two out of the first three options are correct. - Answers - 4)
The degree of response to selection is a function of the superiority of the selected group
and the heritability of the trait. If we want to improve selection response, we can do what
to the superiority of the selected group?
1) Maintain the size of the selected group to prevent inbreeding.
2) Decrease the size of the selected group while increasing the difference between the
selected group and the rest of the population.
3) Increase the size of the selected group by including more individuals from the general
distribution of the population. - Answers - 2)
Selection response depends upon how well you pick animals and how heritable the trait
is. Heritability is often considered to be fixed so improving selection response normally
focuses on selecting. However, if you wanted to look at heritability as a source of more
selection response which of the following is more correct?
1) Although σA2 remains fairly constant, h2 can be improved by reducing σE2 through
more precise measurements or greater quality control.
2) σA2 remains fairly constant, h2 must also stay fairly constant as a result. - Answers -
1)
In addition to selection differential and heritability, time can also be a factor in selection
response. We can improve response in a fixed time by ...
1) Not worrying about it. The generation interval for a species is constrained by the
biology of the species and there isn't much that can be done about it.
, 2) Selecting animals sooner in life and randomly mating them sooner to produce the
newer generations sooner.
3) Selecting animals later in life so they are more stable members of the population and
more likely to contribute better progeny. - Answers - 2)
When making selection decisions, the size of the selected group can affect the potential
for accumulating inbreeding. To avoid inbreeding and improve selection response even
with a small selected group, one of these options would work better than the others...
1) Select the best and smallest selected group you can get away with, mate the best to
the best and avoid matings between relatives within this small group.
2) Select the best and smallest selected group you can get away with and avoid
matings between relatives within this small group.
3) Avoid selecting any relatives so random mating cannot possibly result in an increase
in inbreeding. - Answers - 1)
Among the 3 cases of ANOVA for calculating heritability there are 5 different ways to
compute heritability. The ranking is determined by how close the calculation matches
heritability. Any ties in ranking can be decided by considering the amount of information
used in the calculation (more is better). Rank the 5 different ways of calculating
heritability from best (1) to worst (5) using the matching system below.
1) Case 3 Sires and Dams h2 = 2(σs2 + σdams2) / σP2
2) Case 3 Dams h2=4σdams2/σP2
3) Case 1 Sires h2=4σs2/σP2
4) Case 2 Sires h2=2σs2/σP2
5) Case 3 Sires h2 = 4σs2 / σP2 - Answers - 1. 5)
2. 3)
3. 1)
4. 4)
5. 2)
Match the following three different types of selection to the model that is used to predict
or describe the selection response you would achieve with that type of selection.
1. Finite locus model
2. Infinitesimal model
3. Hybrid model
a) R = Sh2
b) BV(FF) = 2α1
c) R = 2α1 + Sh2 - Answers - 1. b)
2. a)
