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Genotypes and Linkages for Drosophilas

A hairy-winged (h) Drosophila female is mated with a yellow-bodied (y), white-eyed (w) male. The F1 are all normal. The F1 progeny are then crossed and the F2 that emerge are
Females: Wild-type 757
Hairy 243
Males: Wild-type 390
Hairy 130
Yellow 4
White 3
Hairy, yellow 1
Hairy, white 2
Yellow, white 360
Hairy, yellow, white110
Give genotypes of the parents and F1 and note any linkage relations and map distances.

Ans: I have got h++/h++ for the female parent mating with +yw/+yw male. The F1 genotype that I have got is h++/+yw, which would all be normal. I dont know if this is right and I am having some trouble with the linkages.

Solution Preview

This is a classic example of a three-point testcross because it uses 3 recessive mutations to gauge linkage. If all of the genes are unlinked, you have an equal chance of all combinations occurring, however you can see from the data that there are not equal numbers of the F2 progeny.
<br>The easiest way to look at this is to draw a chart with each genotype and the relative frequencies. See attachment.
<br>Just a ...