INDEPENDENT MENDELIAN INHERITANCE 8&9 
The F. population produced by mating two F, individuals will be 
made up of F; gametes as shown in the checkerboard analysis in Fig. 
43. When like phenotypes are collected the ratio in each sex is 3 long 
red:3 long white:1 vestigial red:1 vestigial white. This is very 
different from the typical 9:3:3:1 ratio of a dihybrid, but it is strictly 
in agreement with experimental observations and chromosome behavior. 
The reciprocal cross gives different results and for that reason we 
V(wX) v(wX) VY vY 
V(WX)| VV(WX)(wX) Vo( WX) (wX) VV(WX)Y Vo(WX)Y 
long red 9 long red 9 long red # long red 
V(wX) VV (wX) (wX) Vo(wX) (wX) VV (wX)Y Vo(wX) Y 
long white 9 long white @ long white #7 long white 7 
v(WX) Vo(WX)(wX) vv( WX) (wX) Vo(WX)Y vv(WX)Y 
long red 9 vestigial red 9 long red vestigial red f 
v(wX) Vo(wX)(wX) vv(wX)(wxX) Vo(wX)Y vv(wX)Y 
long white 9 vestigial white 9 long white 7 vestigial white 7 
Fie. 43.—Checkerboard analysis of the Ff: obtained by crossing vestigial white Q with 
long red o in Drosophila. 
V(WX) v(WX) VY vY 
V(WX)| VV(WX)(WX) Vo(WX)(WX) VV(WX)Y Vo(WX)Y 
long red 9 long red @ long red 7 long red & 
V(wX) VV(WX)(wX) Vo(WX) (wX) VV(wX)Y Vo(wX)Y 
long red @ long red 9 long white #1 long white 
v(WX) Vo(WX)(WX) vo(WX)(WX) Vo(WX)Y vv(WX)Y 
long red 9 vestigial red 9 long red @ vestigial red 7 
v(wX) Vo(WX) (wX) vo(WX) (wX) Vo(wX)Y vo(WX)Y 
long red 9 vestigial red 2 long white 7 | vestigial white 7 
Fic. 44.—Checkerboard analysis of the F2 obtained by crossing long red 2 with vestigial 
white o&. Reciprocal of cross analyzed in Fig. 43. 
shall go through it briefly to show that this difference is a necessary con- 
sequence of the chromosome behavior. When a long red female, genetic 
formula VV (WX)(WX), is mated to a vestigial white male, vwv(wX)Y, the 
F, individuals are long red females, Vo(WX)(wX), and long red males, 
Vo(WX)Y. The F females then give the same four types of eggs as 
those of the reciprocal cross, viz., 
V(WX) V(wXx) 
v(WX) v(wX). 
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