(Solved) Genetic and Environmental Variance + broad heritability (MG chpt 21)

darwincalledit

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11 years ago

Genetic and Environmental Variance + broad heritability (MG chpt 21)

In a cross of two pure-breeding lines of tomatoes producing different fruit sizes, the variance in grams (g) of fruit weight in the F1 is 2.20 g, and the variance among the F2 is 5.70 g.

Determine the environmental variance VG for the trait.
Determine the environmental variance VE for the trait.
Determine the broad sense heritability of the trait.

How do I approach this problem? I know the formulas: Vp = Ve + Vg and H^2 = Vg/Vp. I just don't know how to use those numbers. Help? Frowning Face

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ochorios

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11 years ago

Sample Question

In a cross of two pure-breeding lines of tomatoes producing different fruit sizes, the variance in grams(g) of fruit weight in the F1 is 2.10 g, and the variance among the F2 is 6.00 g.

Part A) Determine the geneti? variance VG

for the trait.( 3 sig figs)

Part B) Determine the environmental variance VE for the trait. (3 sig figs)

Part C)Determine the broad sense heritability of the trait.(3 sig figs)

Answer:

Vp = Vg + Ve

two pure bredding lines are crossed

i.e an AA is crossed with aa

i am assuming it to be a cross between AA and aa

asssuming the two pure bred plants to be of different genotypes

AA x aa

F1 Aa

now all the genotypes are Aa

so there is no genotypic variance in F1

i.e for F1 - Vg= 0

Vp = Vg + Ve

2.10 = 0 + Ve

Ve= 2.10g

now this Ve should remain the same in F2 too

assuming ideal conditions and the environment not changing

in F2

Vp = Vg + Ve

6.00= Vg+ 2.10

Vg= 3.90 g

broad sense heritability= Vg/Vp

= 3.90/6.00

= 0.65

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ochorios

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11 years ago

Sample Question

In a cross of two pure-breeding lines of tomatoes producing different fruit sizes, the variance in grams of fruit weight in the is 2.25 , and the variance among the is 5.40 . THANK YOU FOR YOUR HELP Part A Determine the geneti? variance for the trait. Express your answer using three significant figures. = SubmitMy AnswersGive Up Part B Determine the environmental variance for the trait. Express your answer using three significant figures. = SubmitMy AnswersGive Up Part C Determine the broad sense heritability of the trait. Express your answer using three significant figures.

Answer

Ans a : Vp = Vg + Ve, Vp= 5.4, Ve = 2.25, 5.4-2.25= 3.15 Ans b : because pure breeding F1, Vg of F1 is 0. Ve+Vg= Vp Vp= 2.25 (given F1) Ve+0 = 2.25, so Ve= 2.25 Ans c : Vp= 5.4, Ve = 2.25, Broad sense Vg/Vp = 0.416

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darwincalledit Author

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11 years ago

THANK YOU VERY MUCH FOR THAT AWESOME DETAILED EXPLANATION!! Grinning Face

I heart you.

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