Heliconius melpomene is a species of butterfly with ZW sex d

Heliconius melpomene is a species of butterfly with ZW sex determination. H. melpomene\'s wing spots are normally orange, but a recessive Z-linked mutation causes the spots to be yellow, while a recessive autosomal mutation causes the spots to be red. Butterflies homozygous (or hemizygous) for both mutations have no wing spots. What are the expected F₁ and F₂ phenotypes from a cross between a red-spotted female and a yellow-spotted male?

Solution

The Heliconius melpomene butterfly having sex determination ZW have normally orange wing spots.

Given

Recessive Z linked mutation causes the spots to be yellow, if Y is the dominant gene the y represents the recessive gene. The recessive autosomal mutation causes the spot to be red,the recessive autosomal mutation represented by rr.

a) WX represents female

b) WW represents male

Given-:

F1 generation

The red spotted female is crossed with yellow spotted male

ZWrr X ZZy

ZZ, WrrZ, ZZy, WrrZy

It gives 1 hemizygous butterfly, 1red spotted female butterfly, 1 yellow spotted male and 1 normal orange wing male butterfly.

The F2 generation gives the same result.