Budgerigars by Barrie Shutt

If green comes from 1 parent that is not split for blue it shows in 100% of the chicks (all split)
If green comes from only 1 parent that is split for blue you get 50% green all split
If green comes from both parents that are not split for blue 100% green (none split)
If 1 parent is green split for blue & the other is green not split - 50% green not split, 50% green split
If both parents are green split for blue – 50% green split, 25% green not split, 25% blue series



DOMINANT MUTATIONS

Dominant mutations need only come from 1 parent to show (works the same as green)
1 parent double factor – 100% single factor
1 parent single factor – 50% single factor
Both parents double factor – 100% double factor
If 1 parent is single factor & 1 is double factor – 50% double factor, 50% single factor
Both parents single factor – 50% single factor, 25% double factor, 25% don’t have the mutation



RECESSIVE MUTATIONS

Recessive mutations must come from both parents to be visible
If both parents are the recessive mutation – 100%
If 1 parent is the mutation & 1 is split for it – 50%
If both parents are split for the mutation – 25%
If 1 parent is the mutation and the other has no genes for it there will be no visible chicks of the mutation but they will all be split for the mutation
If 1 parent is split for the mutation & the other doesn’t have the gene there will be no visable chicks of the mutation but about 50% will be split for it



SEX-LINKED

Sex-linked mutations must come from the male to be visible
If a sex linked mutation only comes from the male is only shows in female offspring
A female can’t be split for a sex-linked mutation
If the male is the sex-linked mutation all his daughters will show it
If the male is split for the sex-linked mutation half of his daughters will show it
If the female is the sex-linked mutation and the male is split for it – half of both sexes will show it
If both are the sex-linked mutation – 100% of both sexes will be the mutation
If a female is a sex-linked mutation and the male has no gene for it there will be none of the mutation among the chicks but all the male chicks will be split for it



DOUBLE & SINGLE FACTOR

To be a double factor of any mutation the gene must have come from both parents
A single factor of a gene can come from just one parent
Usually the term Double Factor is used to describe dominant mutations that have received a dominant gene from each parent
In some mutations, but not all, double factors will look different from single factors



COMBINING MUTATIONS

Mutations are inherited independently. This means that if 2 dominant mutations like dominant pied and spangle are mated together you can calculate the inheritance of each mutation separately as if they were mated to a normal then combine the results

The spangle gene:
Spangle 50%, normal 50%

The Dominant pied gene:
Dominant pied 50%, normal 50%

If we use the spangle result as a base half of the spangles will be also dominant pied and half a the normals will be dominant pied

So the combined results will be:

Spangle 25%
Combination dominant pied spangle 25%
Normal 25%
Dominant pied 25%