Multiple Alleles and Their Inheritance

As discussed on the Budgie Genetics page, multiple alleles occur when a gene mutates into several versions of itself. In budgies the following are examples:

'Dilute' genes
- Dil = normal strength body color and markings (wild type)
- dil = dilute
- dilgw = greywing

'Blue' gene
- Bl = green body color (wild type)
- bl1 = blue
- bl2 = blue 2 - aka yellow face 1
- blyf2 = yellow face 2
- blgf = golden face

Inheritance of Multiple Alleles

This situation gives us something new to consider when working out the results of matings.

The basics are the same, the altered genes will be dominant or recessive to the normal gene, but they can also be dominant, recessive or incompletely dominant to each other.

So, firstly, lets look at the order of dominance for these genes.

'Dilute' genes

Firstly, lets start with the understanding that clearwing is a variation of greywing and not a separate gene mutation, so it is not included as a separate allele in the expamples. So,

- Dil = normal strength body color and markings (wild type)
- dilgw = greywing
- dil = dilute

This means that normal is dominant over all the others, greywing is dominant over dilute, so dilute is recessive to both.

As a budgie can only have two copies of any particular gene it means a bird can only carry two of these four genes. So, if someone tells you they have a budgie that is normal/greywing-dilute, then they have a problem... The genotype of such a bird would be Dil/dilgw-dil, which means the bird would have to have three copies of this gene!

The possible combinations for this set of alleles are:

- normal
- normal/greywing
- normal/dilute

- greywing
- greywing/dilute

-dilute

The inheritance of multiple alleles will follow the usual pattern of dominant, recessive, incomplete dominance, sex-linked etc. You really just have to understand the way the they relate to work out the results. Lets do an example...

- Greywing/dilute (dilgw/dil) x normal/dilute (Dil/dil)

- the greywing/dilute can pass on 'dilgw' or 'dil'
- the normal/dilute can pass on 'Dil' or 'dil'


Which gives us this result:
- 25% Dil/dilgw = normal/greywing
- 25% Dil/dil = normal/dilute
- 50% dilgw/dil = greywing/dilute

Half the chicks will look normal so you won't be able to tell visually what they are split for. The other half will be greywings split for dilute.

Those are the basics, so long as you know which genes you are working with and how they relate then you should be able to breed for the varieties you would like.

Feel free to contact me with questions!

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