A Z-linked gene in gouldian finches ( Erythrura gouldiae ) of Australia controls

Question

A Z-linked gene in gouldian finches (Erythrura gouldiae) of Australia controls a red headed versus black headed phenotype (the presence or absence of black eumelanin pigment in the feathers on the bird's head). The black headed phenotype is recessive to red.

What are the expected phenotypes of male and female offspring from a black headed male crossed to a red headed female?

The phenotypes are given in male, female order.

A) red/black, red

B) red, red

C) black, red

D) red, red/ black

E) red/ black

Explanation / Answer

Sex determination in finches depend on Z-W inheritance; ZZ are males & ZW are females.

Here, the gene is Z-linked.

ZR: allele for red head

ZB: allele for black head

ZR>ZB

A black headed male crossed to a red headed female;

ZBZB (male black headed)...........X..............................ZRW (red headed female)

Gametes...........ZB.......................................................ZR, W

F1.......ZBZR( male; red headed)...............ZBW( female; black headed)

Hence, the phenotypes are in male,female order are - red, black

The correct option is (E).

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