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:
- Dil = normal strength body color and markings (wild type)
- dil = dilute
- dilgw = greywing
- dilcw = clearwing
- Bl = green body color (wild type)
- bl1 = blue
- bl2 = blue 2 (yellow face mutant 1)
- blyf2 = yellow face mutant 2
- blgf = golden face
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.
- Dil = normal strength body color and markings (wild type) - dilgw = greywing - dilcw= clearwing - dil = dilute
This means that normal is dominant over all the others, greywing and clearwing are incompletely dominant to each other, clearwing and greywing are dominant over dilute, so dilute is recessive to everything.
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:
- greywing clearwing
- clearwing greywing
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/clearwing (Dil/dilcw)
- the greywing/dilute can pass on 'dilgw' or 'dil'
- the normal/clearwing can pass on 'Dil' or 'dilcw'
Which gives us this result:
- 25% Dil/dilgw = normal/greywing
- 25% Dil/dil = normal/dilute
- 25% dilgw/dilcw = greywing clearwing
- 25% dilcw/dil = clearwing/dilute
Half the chicks will look normal so you won't be able to tell visually what they are split for. One quarter will be clearwing (clearwing/dilute), as clearwing is dominant over dilute. As greywing and clearwing are incompletely dominant the greywing clearwing form an intermediate between each type. This creates a bird called a full bodied greywing. It has the wing markings reduced by 50% like a greywing, but has the full body colour and cheek patches like a clearwing.
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!