The Budgie & Parakeet Place Genetics Guide:
Opaline BudgieGenetics of Opaline

Summary:
Opaline - sex-linked recessive
Normal - dominant

Opaline is a sex-linked mutation. This means that the gene is located on the Z-chromosome. Male budgies have two Z-chromosomes (ZZ) and female budgies have a Z-chromosome and a W-chromosome (ZW). Since the gene is recessive to normal, male budgies must have two opaline genes (one on each x-chromosome) to be an opaline variety. However, since female budgies have only one Z-chromosome, if their Z-chromosome has the opaline gene, they will be the opaline variety. It is because females need only one gene to express the trait that sex-linked mutations such as opaline are more common in female budgies. Here, we will represent the opaline gene on the Z-chromosome as "Zo" and the Z-chromosome with the normal gene as "Z". There are three genotype possibilities for a male budgie:

And there are two genotype possibilities for a female budgie:

Below are some punnet square examples of pairings. As you will see, if your goal is to breed a sex-linked mutation like opaline, besides breeding two visually opaline budgies, the best results will be from the pairing of a male who is split for opaline to an opaline female.

A normal male budgie and an opaline female budgie
ZZ x ZoW

Z Z
Zo ZZo ZZo
W ZW ZW

Offspring Phenotype Results:
Males: 100% Normal
Females: 100% Normal

Offspring Genotype Results:
50% Male split for opaline (ZZo)
50% Female normal (ZW)

An opaline male budgie and a normal female budgie
ZoZo x ZW

Zo Zo
Z ZZo ZZo
W ZoW ZoW

Offspring Phenotype Results:
Males: 100% Normal
Females: 100% Opaline

Offspring Genotype Results:
50% Male split for opaline (ZZo)
50% Female opaline (ZoW)


A male split for opaline budgie and a normal female
ZZo x ZW

Z Zo
Z ZZ ZZo
W ZW ZoW

Offspring Phenotype Results:
Males: 100% Normal
Females: 50% Opaline, 50% Normal

Offspring Genotype Results:
25% Male normal (ZZ)
25% Male split for oplaine (ZZo)
25% Female normal (ZW)
25% Female opaline (ZoW)


A male split for opaline and a female opaline budgie
ZZo x ZoW

Z Zo
Zo ZZo ZoZo
W ZW ZoW

Offspring Phenotype Results:
Males: 50% Opaline, 50% Normal
Females: 50% Opaline, 50% Normal

Offspring Genotype Results:
25% Male split for opaline (ZZo)
25% Male opaline (ZoZo)
25% Female normal (ZW)
25% Female opaline (ZoW)

© 1997-2012 Melinda (Mindy) Amaral
This website in its entirety is owned, designed, coded, and scripted by The Budgie and Parakeet Place founder and webmaster Mindy Amaral. Please ask permission before adapting any of its contents for personal use.