Gouldian genetics

[trevorama]

I've looked at Gouldian genetics articles and my brain pretty much shuts down, so thought I'd ask to see if anyone can tell me "what I'll get".
Our female is yellow back-purple breast-black head (although it looks off-white) and our male is green back-orange head-purple breast. I understand he's a "normal" and she's "yellow". Would any of the babies have black heads?
Hope that makes sense. Thanks

[TammyS]

Well...that depends

If this pair is not split for any other head colors - than no, you will not be able to produce BH from this pairing. This is what you would produce:

50% Male >> Red / Black / Orange (Head) - Purple (Chest) - SF Yellow (Body)
50% Female >> Red / Orange (Head) - Purple (Chest) - Green (Body)

But if either of them also carry another head color...that could change the outcome.

[rottielover]

In order to express a yellow (orange) head, the bird must have at least one "Red Z" (gene for red head on his Z sex chromosome). In order to have a yellow head the bird has to have 2 genes (that are not linked to the Z sex chromosome) for yellow head.

So your male bird has two green Z genes and one or both have the gene for red head (which is dominate), and he also has another chromosome and both of those carry the Yellow Headed gene.

Your female bird has only one Z gene and it's Yellow back and black head.

Because your female is a yellow back she can only pass on the yellow back gene, therefore all the male chicks produced from this union will be Dilute back. (Dilute is the combo of green and yellow backs, producing a lighter green/grey looking back color).

As far as head colors, here's where things are going to get a little complicated, so bare with me...

Red head is dominate to Black head, so if your bird has just 1 red head gene and the other is black head, the bird will show a red head.

So we already know that the female bird has a Black headed Z gene, and your male bird has 1 of his Z's as a red head, and possibly both.

The only way to get a black head chick from this pairing would be if your male bird is "split" and has 1 red gene and 1 black gene. Additionally your female bird could be carring a yellow head gene.

Let's assume "worst case" senerio and say that your male and female birds are split (when we can't be sure if they are or not)... This way you can see all the "options" ;)

Let's assume your male bird has:

Head Gene's: Z 1 Red x 1 Black (could be 2 x Red)
Has 2 yellow head gene's
Body Gene's: 1 Green x 1 Green
Chest Gene's: 1 Purple x 1 Lilac or White (Could be 2 x Purple)

Let's assume your female bird has:

Head Gene's: 1 Black
Could have 1 yellow head gene
Body Gene's: 1 Yellow
Chest Gene's: 1 Purple

Now, since yellow head is NOT linked to the Z sex gene, it get's complicated....

NOT taking into account the yellow head gene, and assuming the above splits I get the following:

25% chance for Dilute back, Red Head Male which is split for black head
25% chance for Dilute back, Black Head Male
25% chance for Green Back, Red Head Female
25% chance for Green Back, Black Head Female

Now that is only on the slight chance that your birds are split, when in fact the could be double factor and have 2 of the same gene, which would change everything.

Without knowing the parent history of both birds, it's impossile to accuratly predict what gene's the parents have until they've had a few clutches and you see what all the babies turn out as.

I hope that helps out and didn't make your head spin too bad ;)

[trevorama]

wow. thanks for taking the time to explain all that. I really appreciate it and actually (sort of) "get it". I'll re-read it a few times and it'll make even more sense.

[Hilary]

Get the freeware by Carlos Matos - Gouldian Genetic Forecaster. I learned so much playing with it, and all of this genetic stuff actually started to finally make sense. You can email Carlos at C_Matos@Bigfoot.com and ask him for a copy. What's cool is that he uses the illustrations developed by Crystal (developer of our beloved Finchforum).

[fairestfinches]

Just to clarify, the yellow head color is NOT caused by a specific gene. It is caused by two alleles.

All male gouldians inherit specific sets of genes for head color. Males can be double factor red head, single factor red head (meaning he is split to black head), or double factor black head. Hens are only single factor red or single factor black head.

In addition to the genes responsible for the red or black head, both males and females can inherit one or two alleles for the yellow head color. If they inherit one allele, they are "split" to yellow head and the trait is not visual. If they inherit two alleles, they are considered to be yellow headed and the trait does express itself visually.

In order to see the yellow head color, the bird must have at least one set of genes for the red head. If the bird is black headed, the yellow head trait expresses itself in the form of a yellow tipped beak.

So, to put this together ....
A visually orange headed gould has inherited at least one set of genes for the red head color AND two alleles for the yellow head color.

A visually black headed gould with a yellow tipped beak has inherited the sets of genes for the black head AND two alleles for the yellow head color.

Both are considered to be yellow headed goulds.

Michele

[rottielover]

Yellow head (YH) is an autosomal recessive trait, but also requires at least one red head gene to be present in order to be expressed. If two yellow head genes are present on a bird that has no red head genes (and instead has black head genes), the bird will have a black head with a yellow tipped beak (YTB). This occurs because the bird is genetically a yellow headed bird, but it cannot express the yellow color because the yellow gene depends on the red head gene for expression, and the red head gene is not there. Both cocks and hens can be "split" for yellow head.

Autosomal means that it's a gene on a chromosome that is NOT a sex chromosome (Z and W for birds).

Allele:
One of one or more possible forms of a gene, each affecting the inherited trait somewhat differently.

"Yellow Head" is not an allele. Red head and Black head are allele's of the head color gene on the Z (sex) chromosome. Yellow head genes are not on the sex chromosomes.

Genetic's is an advanced and often confusing topic, especially when gene's from one chromosome can affect the expression of traits linked to other chromosomes.

Hope that helps to clear things up.

I highly recommend reading these pages if your interested in Gouldian Genetics: http://www.finchinfo.com/genetics/index.php

It's extremely well put together!

[fairestfinches]

Thank you RottieLover, but I already have an extensive college education in genetics and correspond regularly with various experts in gouldian genetics.

Please take a moment to re-read my post and maybe you'll see the actual issues I was addressing in your original post.

Michele

[rottielover]

Michele,

As far as I know, I'm using the latest avalible published research.

Your post is essentially correct except for the terminology, which is what I am attempting to point out in my last post. Please re-read my latest post, explaining the terminology and why the yellow head color is not an "allele" of the sex chromosome head color.

Red head and black head are allele's of the head color gene on the Z chromosome. Yellow head and non-yellow head are allele's on different chromosome.

You contend:

"Just to clarify, the yellow head color is NOT caused by a specific gene. It is caused by two alleles. "

However that cannot be the case since an allele is an alternative form of a gene that is located at a specific position on a specific chromosome. If the yellow head gene were an alllele of the head color Z chromosome you could never have a black head bird with yellow tipped beak, because the yellow head gene would have to occupy the head color position on the Z chromosome.

I enjoy these disscussions, as a breeder I'm keenly interested in the topic of genetics

Best Regards.