Suppose that the narrow-sense heritability of wool length in a breed of sheep is 0.92, and the narrow-sense heritability of body size is 0.87. The genetic correlation between wool length and body size is –0.84. If a breeder selects for sheep with longer wool, what will be the most likely effects on wool length and body size?

There is an increase in wool length and a little decrease in body size

Explanation:

Given that:

the narrow-sense heritability of wool length in a breed of sheep is 0.92;     &

the narrow-sense heritability of body size is 0.87.

As these traits approaches 1, the higher the rate that helps them to provide a positive feedback for selection.

The question proceeds by stating that " The genetic correlation between wool length and body size is –0.84."

You see, the functionality of this negative (-0.84) genetic correlation tends to create an imbalance between these heritable traits. As such, there is a shift in the paradigm in which one traits tends to increase and the other trait to decrease.

Now, if a breeder selects a sheep with longer wool, there is an increase in wool length since he selects it although there will be a little decrease in body size due to the negative genetic correlation effect between the two heritable traits.

you know they are heterozygous for a trait because they have it as jj or jj.