Suppose that you are working with flies that are segregating
three traits. You cross a homozygous truncated, vestigial, shaven
fly with a homozygous wild-type, apterous, spineless fly and the F1
flies are all wild-type, apterous, spineless. You next backcross
the F1 flies to a truncated, shaven, vestigial parent. The progeny
from this type of cross are shown below:
truncated apterous shaven 94
truncated vestigial shaven 425
truncated apterous spineless 46
truncated vestigial spineless 19
wild-type apterous shaven 16
wild-type vestigial...