Question

Question 6 You are selecting for taller corn plants. Your starting population of corn has a mean height of 4 feet. You select for 6 foot stalks. The heritability of corn height in your population has already been determined to be 0.80. How tall will your next generation of corn grow to be

Answer 1

Answer:

The value of X₁, which is how tall the new generation of corn will grow equals 5.6 feet.

Explanation:

Before answering the question, we need to know a few concepts.

Artificial selection is the selecting practice of a specific group of organisms in a population -that carry the traits of interest- to be the parents of the following generations.

Parental individuals carrying phenotypic values of interest are selected from the whole population. These parents interbreed, and a new generation is produced.

The selection differential, SD, is the difference between the mean value of the trait in the population (X₀) and the mean value of the parents, (Xₙ). So,

SD =  X₀ - Xₙ

Heritability in the strict sense, h², is the genetic component measure to which additive genetic variance contributes. The heritability might be used to determine how the population will respond to the selection done, R.

h² = R/SD

The response to selection (R) refers to the metric value gained from the cross between the selected parents. R can be calculated by multiplying the heritability h², with the selection differential, SD.

R = h²SD

R also equals the difference between the new generation phenotypic value (X₁) and the original population phenotypic value (X₀),

R = X₀ - X₁

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Now that we know these concepts and how to calculate them, we can solve the proposed problem.

Available data:  

• You are selecting taller corn plants.
• The population of corn has a mean height of 4 feet → X₀
• Parental selected plants of 6 feet  → Xₙ  
• Heritability of corn height is 0.8 → h²

According to what we sow previously, we need to find out the value of X₁, which reflects how tall the new generation of corn will grow.

• We know that R = X₁ - X₀, so we need to clear this formula to calculate X₁

X₁ = R + X₀

We already know that X₀ = 4 feet,

Now we need to calculate R.

• R = h²SD  

We know that h² = 0.8,

Now we need to calculate SD

• SD = X₀ -  Xₙ    

Xₙ = 6 → Parentals media height

X₀ = 4 → Population media Height

SD = X₀ - Xₙ      

SD = 4 - 6

SD = -2 feet.

Knowing this, we can calculate R

R = h²SD

- h² = 0.8

- SD = 2

R = 0.8 x 2

R = 1.6

Finally, once we know the R-value we can calculate the X₁ value

X₁ = R + X₀

X₁ = 4 + 1.6

X₁ = 5.6