Gouldian genotypes

[natamambo]

I was sent the following by a PM (author shall remain anonymous unless they choose to reveal themselves here):

Just wondering if you would know if there is a standard genotype coding when dealing with gouldians?
I have seen three different types so far
for example
I have seen a BH PC GB hen described as
Z RZ+ G+ W o+ o+ wb+ wb+ bl+ bl+
also as
Zbh,g W Ap Ap
and yet again as
Xb,G; Y; i-, i-, P, P, m-, m-

I thought I'd reply publicly as this has come up a lot lately:

I have not come across a "standard" notation for Gouldian genetics and in fact a quick browse of the web to look for modern genotype notation practice (my training is 30 years old and it's nearly 20 years since I quit teaching genetics) suggests that the + to denote wild is in use in some schools (I'd never seen it before) as opposed to a Gg form where G is the dominant trait and g is the recessive trait. BTW the different forms of a gene are called the allele (this becomes important soon). Throwing the Z in is just to remind the user that the inheritance pattern is sex-linked because the allele is on the Z chromosome. I was surprised in my web reading that the + and capitals now both exist, maybe it's an Oxford vs Cambridge kind of thing or maybe it's a purist vs mutation breeder kind of thing. Of course by my way of thinking just because black head is the most common in the wild that doesn't mean it's the wild type as the red and yellow and yellow tipped beak black all occur naturally in the wild - which means choosing which gene to put the + on is a bit problematic (and all the more reason to use the capitals in my mind). Calling the black head the wild type genetically is equally as dangerous in my opinion as calling black curly hair wild type (if you hold that we all descended from Africans).

Let's break it down for you:
Hen: sex chromosomes are ZW (if human would be XX, birds and reptiles are the other way around). As sex linked chromosomes are carried on the Z chromosome that impacts on the genotypes. (Just out of interest there are a very few characteristics which are carried the human Y chromosome which means that they can only be inherited by the male and every male offspring will have the characteristic, one is excessively hairy ears!).

Head colour: this is the most confusing one if using the + notation as does GGF. Z is in the notation as it is sex linked. GGF uses ZRZ for red and ZRZ+ for black (don't know why the Z is used again by him) but the use of caps here becomes very misleading especially as an educational tool. Yes, Red is dominant over black but that means the wild type (the + in this case) is recessive if you consider black to be the wild type. If it was me, I'd use R for Red and r for black, thus the black headed hen is Zr (whereas the cock is ZrZr as he needs the r allele on both Z chromosomes to be a black head). However, the yellow head adds a second dimension. I'd call the alleles Yh and yh rather than anything else which doesn't make sense to the user. Thus a (hen) bird can be:
ZRZR YhYh which means it is pure red head
ZRZr Yhyh will be split black head and split yellow head
ZRZR yhyh will be yellow head
ZrZr yhyh will be a yellow tipped beak black head.
Note that we are now using both allele combinations because yellow requires red but is independent of it.

Green is wild type (no arguments here from me this time) but here comes another confusing factor, because body colour and back colour are controlled separately but are often (incorrectly) used interchangeably (I'll perpetrate that myth later for the sake of simplicity). Thus the Australian yellow has a yellow back and so does the European yellow but they are for different reasons genetically and with slightly different overall phenotypes because of the splotchiness of the green that can occur in Aus yellow. All birds (apart from blue) have a yellow belly so saying a mutation is a yellow body is not correct really. Where Aus yellow is different is the way it also gets rid of the purple breast in most cases. Because of this (and the presence of blue) as with red and yellow heads it would be normal to show the notation of all genes / alleles where known.

So if I was creating a "new" standard... I'd use the following:
Back colours. I'd use Yb = Euro yellow / yellow back which is dominant over green, so a to be a yellow back hen would be ZYb, a cock could be ZYbZYB (double factor) or ZYBzyb (single factor). Note that the use of Z here is independent of head colour. Let me emphasis this is a back colour only. The reason single and double factor are used here but not for any other trait is that the allele's effects are cumulative. In a hen there is only one set so the bird is yellow back, a cock needs two sets to be full yellow back (DF) otherwise he is technically only partially yellow back but it shows as partial dilution rather than splotchiness as a pied bird would have.

After that we have bib colours. These are straight forward until lilac exists. Most texts suggest lilac is dominant over white but recessive to purple. While I'm far from an expert on Gouldian colours it's my suspicion that bib colour is akin to human hair colour. Human hair colour is generally believed to be brown or red with red the recessive but the amount of brown may be controlled by as many as 8 alleles which are cumulative in effect from blond to black. If my theory is correct we have white or purple but grades of purple, this would be borne out by the people who say that even lilac to lilac produces unpredictable results. For that reason I'll ignore lilac (as most genetics teachers ignore blond-black and discuss only red vs non red) in the genotype and so the bird is either WW / Ww (purple, purple split white) or ww.

Now we get to the body colours and for the sake of simplicity I'll treat Aus yellow as a body colour as it also affects bib colour. If I was teaching Gouldian genetics I'd use the following:
Bb for blue so a BB or Bb bird isn't blue (and therefore is green) a bb is blue
Dd for Aus dilute so a DD or Dd bird isn't dilute (and therefore is normal) a dd is dilute
Ayay for Aus yellow so a AyAy or Ayay bird isn't Aus yellow (and is therefore normal) an ayay bird is Aus yellow.

Note I haven't used green in the genotype at all, rather I have used the system that it is not something else and therefore is green. I think it is simpler this way as we are therefore saying it is blue or not blue, Aus yellow or not Aus yellow and so on. Add green to the genotype and you have to double up.

The Lutino / Albino is sex linked but recessive so the inheritance pattern is the same as for black head. Lets call it ZA for albinism (since lutino is a form of albinism and the same gene causes lutino and white depending on body colour.

So far I haven't really answered your question. I will reiterate again I have not seen a standard and in my opinion that lack of a standard is holding back the science as the more breeders that we have understanding the inheritance patterns the sooner new mutations can be understood. However the full genotype from what you describe is not known as we don't know what alleles it is carrying for white bib, Aus yellow, blue or Aus dilute. All of the genotypes you list are correct in the eye of the beholder but I can't tell which is which characteristic so the genotype doesn't tell me the phenotype. Give me a genotype that describes the phenotype any day, especially as a teaching tool.

In its simplest form your hen, using my notation, is ZrPP or ZrPp and that is we can tell from your description. From there you need to add the others so it would be (assume no splits) Zr,ZA,Zyb,PP,BB,DD,AyAy

[Diane]

Ill put my hand up for asking the question
Thanks for the answer, it will take me a while to understand it , but thanks.

[ikhom]

Thanks natamambo for answering Diane's question.
I'm trying to create genetic forecast for my website and I was looking for the ways to code genotypes of Gouldians and other finches. The second coding was actually mine. (I'm trying it on Gouldians, RTPF, BFPF...). I started to group mutations by chromosomes, the same way as system analyzes them, so I can use the same algorithm on different species.

[natamambo]

Ikhom has there been genotyping of the genes to chromosomes (haven't seen any but I'm new to Gouldians if not genetics) or are you simply using sex and autosomal chromosomes?

I'd suggest you steer away from green in the genotype or you have to say the birds is green and not blue otherwise green can be the default and blue the mutation. This becomes important when you have multiple not greens. Gouldians vary from budgies (and many other parrots) which simply have green and not green and then all forms are based on this basic premise, having multiple not greens is different. It is for this reason I suggested budgies to you in the other thread.

[ikhom]

natamambo,
I just updated my Genetic Forecast (links on previous post) that I worked on for several days. Maybe it will give you a better idea how I'm planing to implement it. (Still working, not all choices have been mapped.)
I wanted to make checkbox selections for each mutation, but after trying with Gouldians...had to make multiple choices since there are two different mutations on Z chromosome. Yes, right now I separated sex and autosomal chromosomes. I'm assuming that mutations located on different autosomal chromosomes.
I can remove green from genotype, but I find it easier to see the phenotype from genotype. After dealing with Gouldians I'm not sure what mutation is after all.
Now since I defined the database I'm going to try to map other birds too.

[natamambo]

IKHOM

You can have DF and SF RH and YH Yellow backs (since I presume you mean European yellow rather than Australian Yellow when you say Yellow body).

[ikhom]

You can have DF and SF RH and YH Yellow backs (since I presume you mean European yellow rather than Australian Yellow when you say Yellow body).

I thought I have. Maybe I'm missing something.
Male could be DF and SF for RH and YH Yellow back.
Link for Genetic Forecast.