A rancher determines that the average amount of wool produced by sheep in her flock is 15 kg per year. In an attempt to increase the wool production in the flock, she picks 5 male and 5 female sheep with the highest wool production; the average amount of wool produced per sheep by those selected is 25 kg per year. She interbreeds these selected sheep and finds that the average wool production among the progeny of the selected sheep is 22 kg per year. After multiple generations of selection for increased wool production in her flock, in generations 20 and 21 of selection the rancher notices that there is no response to selection. She is getting tired of shearing sheep, anyway, so she decides to try two generations of selection for decreased wool production ("reverse selection"). She is surprised when she does not see a response to this reverse selection. What is the most likely explanation for the lack of response to selection for either increased or decreased wool production? A. There is a positive correlation between wool production and sheep survival (increase in wool production is correlated with a increase in sheep survival) B. There is a negative correlation between wool production and sheep survival (increase in wool production is correlated with a decrease in sheep survival) C. There is no environmental variation remaining for wool production in the flock D. There is no genetic variation remaining for wool production in the flock
A rancher determines that the average amount of wool produced by sheep in her flock is 15 kg per year. In an attempt to increase the wool production in the flock, she picks 5 male and 5 female sheep with the highest wool production; the average amount of wool produced per sheep by those selected is 25 kg per year. She interbreeds these selected sheep and finds that the average wool production among the progeny of the selected sheep is 22 kg per year.
After multiple generations of selection for increased wool production in her flock, in generations 20 and 21 of selection the rancher notices that there is no response to selection. She is getting tired of shearing sheep, anyway, so she decides to try two generations of selection for decreased wool production ("reverse selection"). She is surprised when she does not see a response to this reverse selection. What is the most likely explanation for the lack of response to selection for either increased or decreased wool production?
| A. |
There is a positive correlation between wool production and sheep survival (increase in wool production is correlated with a increase in sheep survival) |
|
| B. |
There is a negative correlation between wool production and sheep survival (increase in wool production is correlated with a decrease in sheep survival) |
|
| C. |
There is no environmental variation remaining for wool production in the flock |
|
| D. |
There is no |
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