Genetics of Spangle

Summary:
Spangle - dominant
Normal - recessive

There are only two alleles for spangle: the spangle gene and the normal gene. The spangle gene is semi-dominant to the recessive normal gene. This means that a single-factor spangle looks different from the double-factor spangle. Here, we will represent the spangle gene as "S" and the normal gene as "s". Therefore there are three possible genetic combinations for any budgie:

• ss - Two normal genes (homozygous) resulting in a normal budgie.
• Ss - One spangle gene and one normal gene (heterozygous) resulting in a spangled budgie.
• SS - Two spangle genes (homozygous) resulting in a double-factor spangle budgie, which has no markings or color.

As you can see, it is only when one spangle gene and one normal gene is present that a budgie is the actual spangle variety. When two spangle genes are present the budgie has no markings or color, and looks like a lutino/albino except for the red eyes. Below are some punnet square examples of pairings.