Genetics of OpalineSummary:
Opaline - sex-linked recessive
Normal - dominant
Opaline is a sex-linked mutation. This means that the gene is located on the x-chromosome. Male budgies have two x-chromosomes (XX) and female budgies have an x-chromosome and a y-chromosome (XY). 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 x-chromosome, if their x-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 x-chromosome as "Xo" and the x-chromosome with the normal gene as "X". 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.
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A normal male budgie and an opaline female budgie
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An opaline male budgie and a normal female budgie
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A male split for opaline budgie and a normal female
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A male split for opaline and a female opaline budgie
Offspring Phenotype Results: Offspring Genotype Results: |