Genetics Masterclass

[Deleted]

I asked BudgiesBuddy if he would mind teaching me about budgie genetics, and he agreed and suggested making a thread, so here it is. I'm going to make a run down of the information in this post and will keep it updated as we find out more. So, if anyone has any questions or comments to make, feel free to ask them on this thread.

All edits will be made in blue. This post will summarise the information found in the entire thread, but please read on to see full explanations in their original context and to obtain the information a little at a time, as often large chunks like this can be a bit overwhelming.


Green/Blue Colouration
Yellow Based budgies have the dominant allele, B, whilst White Based budgies have the recessive allele, b. Yellow is therefore dominant to White. So:

BB = Yellow Based
Bb = Yellow Based split for White Based
bb = White Based

The reason that Green is dominant to Blue is that only one Green allele is required for the budgie to appear Green. Thus, Green colouration cannot be hidden unless it is Masked by another gene, however Greens can carry other colours as hidden colours. Blue budgies can only be seen visually when both of the alleles for the gene are the recessive form.


Normal Mutation
"Normal" refers to budgies whose colours and markings are like those of wild budgies. Wild budgies are Light Green with Yellow and Black stripes and markings, Dark Blue tail feathers and Violet cheek patches. Sometimes terms like “Sky Blue Normal” or “Dark Green Normal” or “Grey Normal” are used as well. It means that although the base color is different, the budgie markings are like the wild type budgies.


Dark Factor
All budgies have some level of Dark Factor, from none to two. Even albinos and lutinos have Dark Factors, despite the lack of body colour. The two alleles are called Normal and Dark Factor. The Normal allele is recessive whilst the Dark Factor allele is semi-dominant. Semi-dominant means that a budgie with 1 Dark Factor will have a difference appearance than a budgie with 2 Dark Factors. Therefore, Normal is d and Dark Factor is D.
Light Green: dd - 2 Normal alleles. Appears as a light, bright green.
Dark Green: Dd - 1 Dark Factor. Appears as a dark green.
Olive Green: DD - 2 Dark Factors. Appears as a deep olive or dull green.
Sky Blue: dd - 2 Normal alleles. Appears as a very light blue.
Cobalt: Dd - 1 Dark Factor. Appears as a normal blue, deeper than a Sky Blue.
Mauve: DD - 2 Dark Factors. Appears as a very dark blue, perhaps a bit grey?
You can tell that a bird is an Olive Green and not a Grey Green because the cheek patches remain Violet in colour. Grey Greens have Grey cheek patches.
Violet and Grey have nothing to do with Dark Factors. Both are colour adding factors.


Grey Factor
The Grey Factor is a colour adding factor. The Grey allele (G) is dominant to the Normal allele (g), so both single-factor and double-factor budgies will appear the same in colour. The Grey Factor changes the budgies' cheek patches to Grey.
In Green Series budgies, Grey is added to the Green, whereas in White Based birds the original Blue colour instead appears completely Grey.
Dark Factors will impact on the Grey Factor, so budgies with one or two Dark Factors will appear darker than budgies with no Dark Factors.


Violet Factor
The Violet Factor is a colour adding factor but it is not as strong as the Grey Factor. The Violet allele (V) is semi-dominant over the Normal allele (v), so double-factor birds sometimes appear different to single-factor budgies.
Violet usually darkens the body colour, making Light Green appear Dark Green. In Green Series birds and Mauves, Violet may only appear as a sheen, visible mainly around the feet and vent. Sometimes its presence can only be determined via the bird's pedigree or through breeding.
Sky Blue budgies can show Violet colouring, but often appear Cobalt. Only Cobalt birds can show true Violet colouration.


Yellowface
Pending

[BudgiesBuddy]

Normals and Pieds are two different mutations, so they cannot be same.

[BudgiesBuddy]

I think we should start from the "Base Color", as all budgies fall into one of two basic varieties.

This is the easy part as we have only two colors in budgies, i.e. Green and Blue.

All budgies are refereed to as Yellow based and White based, or Green series and Blue series budgies.

Any thoughts on this?






.

[Deleted]

Okay, just checking

My main thoughts are, why are they called Yellow series and Blue series rather than Green series and Blue series?
What are the different colours which make up Yellow series and Blue series?

[BudgiesBuddy]

They are called either Yellow based and White based.

OR

Green series and Blue series.

[BudgiesBuddy]

So there are two basic varieties...

1: Green Series also called Yellow Based (Dominant)
2: Blue Series also called White Based (Recessive)

There are only two Alleles for budgies' base colors. Which is Yellow Based and White Based. The Yellow Based Allele is dominant to the recessive White Based Allele.

Definition:
An Allele is an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. These DNA codings determine distinct traits that can be passed on from parents to offspring. There are two Alleles for each trait. When the Alleles of a pair are heterozygous, one is Dominant and the other is Recessive. The Dominant Allele is expressed and the Recessive allele is masked.

Therefore, if we call the Yellow Based gene B, and the White Based gene b, we can get the following three genetic combinations in budgies.

BB = Two Yellow Based genes, which will result in Yellow Based budgie.

Bb = One Yellow Based gene and one White Base gene, which will result in Yellow Based budgie, which will be split for White Base.

bb = Two White Base genes, which will result in White Based budgie.

[Deleted]

So you're a Yellow Based budgie, BB

So that's how you get the basic colourations, Green, Blue and Green split for Blue.

Would you then say that the other genes are modifiers of this basic colouration and patterning?

[kikkinu]

Jan 7, 2014 11:39:17 GMT BudgiesBuddy said:

So there are two basic varieties...

1: Green Series also called Yellow Based (Dominant)
2: Blue Series also called White Based (Recessive)

There are only two Alleles for budgies' base colors. Which is Yellow Based and White Based. The Yellow Based Allele is dominant to the recessive White Based Allele.

Definition:
An Allele is an alternative form of a gene (one member of a pair) that is located at a specific position on a specific chromosome. These DNA codings determine distinct traits that can be passed on from parents to offspring. There are two Alleles for each trait. When the Alleles of a pair are heterozygous, one is Dominant and the other is Recessive. The Dominant Allele is expressed and the Recessive allele is masked.

Therefore, if we call the Yellow Based gene B, and the White Based gene b, we can get the following three genetic combinations in budgies.

BB = Two Yellow Based genes, which will result in Yellow Based budgie.

Bb = One Yellow Based gene and one White Base gene, which will result in Yellow Based budgie, which will be split for White Base.

bb = Two White Base genes, which will result in White Based budgie.

AHHHH - now it makes alot more sense hehe

[BudgiesBuddy]

Jan 7, 2014 17:06:15 GMT Ira said:

So you're a Yellow Based budgie, BB

So that's how you get the basic colourations, Green, Blue and Green split for Blue.

Would you then say that the other genes are modifiers of this basic colouration and patterning?

Yes I am

That's sort of right. When we start adding or removing or separating one of the two colors, this allows other colors to appear. There are other factors too, which I will explain further.

[BudgiesBuddy]

Jan 8, 2014 23:40:39 GMT kikkinu said:

AHHHH - now it makes alot more sense hehe

Glad it does

[BudgiesBuddy]

There are at least 32 known primary mutations in the budgies. These can be combined to make hundreds of possible secondary mutations and color varieties.

However, in the wild, budgies are Light Green with Yellow and Black stripes and markings, and Dark Blue tail feathers and Violet cheek patches. We use the term “Normal” for budgies, whose markings and colors are like the wild type budgies. Sometimes the terms like “Sky Blue Normal” or “Dark Green Normal” or “Grey Normal” are used as well. It means that although the base color is different, but the budgie markings are like the wild type budgies.

A question is asked frequently that why is Green a dominant color and Blue a recessive color. The answer is that Green requires only one copy of the gene, whereas Blue requires two copies of the gene.

To explain it further, if Yellow pigment is suppressed in Green budgies, we are only left with White. Remember Green is a combination of Yellow and Blue. If the Yellow is taken away from Green, it leaves Blue. And because there is no Yellow base pigment, the budgie appears bright Blue.

Another thing to remember here is that Dominant genes are always visual, except when masked by another mutation. (Masking will be explained later). Because Green is Dominant, no other budgies can carry Green in a hidden form, although the Green budgies can carry many hidden colors.

I will share the “Breeding Expectations Table” later, once we finish discussing the “Dark Factor”, which is next.

[Deleted]

That's a lot of colours!

So how would you tell a Normal from a Pied, @bb? Is it just whether the tail is blue and perhaps the colour of the cheek patches?

Ooh, Dark Factor This is really interesting. So now I should probably edit the first post a bit, and rearrange things into the order they're discussed.

[BudgiesBuddy]

Pieds are many types, and it's not just about tail and cheek patches. Sometimes in order to tell which Pied one has, the only way is to breed the budgie. We will cover it gradually, once we are there.

[BudgiesBuddy]

We get different shades of Blue or Green in budgies because all the budgies have some level of DARK FACTOR. It ranges from no DARK FACTOR, to ONE DARK FACTOR, or TWO DARK FACTORS. Even Albinos (all White) and Lutinos (all Yellow) have DARK FACTOR present but it is unknown due to no color in body feathers.

DARK FACTOR: Semi Dominant
NORMAL: Recessive

There are only two Alleles which determine the darkness of budgies’ body-color. These are NORMAL gene and DARK FACTOR gene. The DARK FACTOR gene is Semi Dominant, and NORMAL gene is Recessive. It means that when one budgie has one DARK FACTOR and one NORMAL gene, the budgie will look different from the other budgie which has two DARK FACTOR genes.

Therefore if we call DARK FACTOR “D” and the NORMAL “d”, we can get the following three genetic combinations in budgies.

dd = Two NORMAL genes, which will result in Light Green OR Sky Blue.
Dd = One DARK FACTOR with one NORMAL gene, will result in Dark Green OR Cobalt.
DD = Two DARK FACTORS, will result in Olive or Mauve.

Wild budgies have NO DARK FACTOR, that’s why we only see Light Green budgies in the wild.

Fundamentally, what DARK FACTOR does is to darken the Blue or the Green color in the body feathers. So here is how it affects the Green and Blue budgies.

A Yellow-based Green budgie with NO DARK FACTOR will be very light or bright Green. It is referred to as Green or Light Green budgie. See below.




A Yellow-based Green budgie with ONE DARK FACTOR will look dark Green. It is referred to as Dark Green budgie. See below.





A Yellow-based Green budgie with TWO DARK FACTORS will look deep Olive or dull Green color. It is referred to as Olive budgie. See below. Here colors are a little washed out because of flash.





We know when the budgies are Light Green, Dark Green or Olive, because their cheek patches will remain Violet. (A Grey Green budgie will have Grey cheek patches.)


Similarly…

A White-based Blue budgie with NO DARK FACTOR will look lighter Sky Blue. It is referred to as Sky Blue budgie. See below.





A White-based Blue budgie with ONE DARK FACTOR will look normal Blue and darker than sky Blue. It is referred to as Cobalt budgie. See below.





A White-based Blue budgie with TWO DARK FACTORS will look very dark in color. It is referred to as Mauve budgie. See below.





A general color guide for Budgie colors and DARK FACTORS.





Remember Violet has nothing to do with DARK FACTOR. Violet and Grey are color adding factors, which will be explained later.

[Deleted]

Makes sense

Is it just the light, BudgiesBuddy, or is the Mauve rather grey looking? By which I mean, it's quite a dull, unsaturated blue colour as well as being very dark? The cheek patches, of course, tell you there's no grey factor, like with the Olive Green.