QUANTITATIVE GENETICS PROBLEM

[hagan]

Hi, need some help, this is driving me crazy, this is not an assignment just review question that i cant get my head around, just need to be pointed in the right directions

 

Two doubled-haploid (homozygous) lines of canola differ in leaflength. In one, the average leaf lengthis 30 cm, and in the other it is 15 cm. In both lines, the variance in leaf length is 2 cm² whengrown in similar environments. In the F₂generation of a cross between these lines, the average leaf length is 22.5 cm,with a variance of 5 cm². (Hint: DO NOT ASSUME THAT THE ENVIRONMENTAL VARIANCE =0)

 

a. What is the genotypicvariance?

 

so from the lecture notes, it doesnt cover much but what i can work out

 

Vp = V_G+V_E+V_GE

 

find V_G = V_P - V_E

 

and if genetic uniform population then phenotypic variance of F1 = V_E

 

and Phenotypic variance of F2 provides and estimate of = V_GE

 

V_G = VGE - V_E

 

F2 = 5cm2 but we don't have F1 so no V_E

 

 

where do i get V_E from if it doesn't equal 0 ??