Gouldian breast colours

An area to discuss new and established colour mutations.
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hanabi
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bjc787 wrote: 11 Dec 2017, 13:28 I'm not that up with gouldian genetics but from the posts i have read it is that lilac breast and white breast are allylic.
which means they occupy the same position on the dna strand
Yes I feel this point is worth highlighting. I may be wrong(!) but it appears we are confusing gene pairs at a single location with those that occupy different locations. If my understanding is correct, the breast colours purple, lilac, and white are affected by a gene pair at a single location in the genome and each of the two genes in that gene pair at that location is tri-state, i.e. the single gene can take on either purple, or lilac, or white, and thus, as a pair, the gene pair can take on P-P, P-L, P-W, L-L, L-W, W-W. Because this is a gene pair it cannot be "triple split", i.e. it cannot be P-L-W (that would require a gene triple, not a gene pair).

I think the reference to fawn and cinnamon in Star finches is a different situation (in my humble opinion, I may be wrong) because my understanding is that those two mutations occupy different locations in the genome. Although they affect the same area of the bird (the overall body colour) they are different locations and therefore act independently. Thus it is possible to have a Star that is normal split fawn split cinnamon. They must be different locations in the genome because one is autosomal recessive and the other is sex-linked recessive.

Another good example is the Bengalese finch and its many mutations like pearl, grey, ino, etc. These are mutations located at different positions in the genome, and thus a single Bengal can be split to all these mutations. This is not the case for Gouldian breast colour, because there we are talking about a single location in the genome.
So it is possible for a purple breasted bird (or 2 of them who are mated together) to carry both the white-breasted & lilac-breasted mutations (be split for both).
Tiaris, did David specifically say that the Gouldian breast gene can be "triple-split"? Could it be that David's comment regarding Gouldian orange head working the same way as breast colour was that they are both autosomal? It would be interesting to hear David's reply when asked whether Gouldian breast colour can be triple split.

There is a huge amount of information on Gouldian breast colour on the web and reference texts, but from what I have read no one has ever suggested that Gouldians can be triple-split to the three colours simultaneously (a genetic impossibility because it is a gene pair).
Marek Buranský knows more than most about Gouldian genetics, and his forecaster does not list any triple-splits for breast colour.

As I have stated before I believe the most likely reason for the two breast colours of Alvin's offspring is that the hen as mated with another cock. Another possibility, perhaps less likely, is that a different hen laid an egg in the same nest. I have recently witnessed both these situations in a community cage; I've seen a hen paired to cock "A" mate to cock "B", and I have another hen that lays eggs randomly in various nests, including a nest that was occupied by another brooding pair. Alvin, do you discount these two possibilities, and if so,can you give a reason why? I understand that you believe the cock is the parent of those two offspring, but it must be possible that he is not the biological parent, surely? And wouldn't either of the above two explanations be far more likely than the possibly that your cock has a very rare purple breast that looks lilac?

Now if "triple splitting" is possible for Gouldian breast colour then please ignore all the above :D


By the way Craig, this site is in agreement with you when you said you believe "dirty white" and lilac are not related:
The above is all in my humble opinion and mentioned in the interests of robust discussion. I am more than happy to be corrected as that is a necessary part of learning.

Cheers.

Ross
alvin

This is the Story, DF pastel blue cock takes on 2 hens every year, breeds with 1 ( how I know, nest results). This year 2017 it had a yellow back hen and a green back hen. The green back always seemed to be close to the nest box and started sitting. I removed the yellow hen and put it in the aviary having green back cocks and yellow back hens the day before I went on holiday. got back four weeks later found 2 large yellow chicks about 2.5 weeks old and 2 young that had just hatched, which died a few days later. This pair went on to produce 3 nests of 4 in each nest having produced all green back hens and SF cocks (All PB). pic of one of them below pink band. The rest of the pairs produced the same SF cocks. all these birds where bred by me and were all 100% purple breasted cocks. All the cocks bred in this aviary are the same as this one (pink ring - which would be the expected result from the pairing ), with exception of the 2 yellow back cocks. For me the DF pastel cock is the only cock that could have fathered these two cocks, white breast and so called iliac breast. Maybe the red head is purple breasted and both the parents are purple split white breasted.
Both these cocks are the same colour under the beak, maybe due to the breast colour they show slightly different in the pictures. They should also be both DF cocks if the father is a DF pastel blue and the mother is a euro yellow hen.
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Tiaris
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So Alvin, a green-backed hen was in the aviary in which these birds were bred? If so, this would totally explain the SF progeny.

Ross, it is indeed possible for double, triple (or more) splits in mutations which have the same modes of inheritance too. Eg Blue, AY & WB in Gouldians.

Also it is possible for double, triple, etc. splits in mutations which determine colour in the very same body part eg. a red-headed Gouldian split to both yellow-headed & black-headed.

I honestly don't know exactly how specific alleles do what they do for various mutations to express themselves, but I do know for certain that each mutation acts in reproduction via its own mode of inheritance irrespective of which other mutations or how many other mutations are also acting in the same bird or animal.
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hanabi
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Tiaris wrote: 11 Dec 2017, 19:55 Ross, it is indeed possible for double, triple (or more) splits in mutations which have the same modes of inheritance too. Eg Blue, AY & WB in Gouldians.

Also it is possible for double, triple, etc. splits in mutations which determine colour in the very same body part eg. a red-headed Gouldian split to both yellow-headed & black-headed.

I honestly don't know exactly how specific alleles do what they do for various mutations to express themselves, but I do know for certain that each mutation acts in reproduction via its own mode of inheritance irrespective of which other mutations or how many other mutations are also acting in the same bird or animal.
Yes I agree with everything you have said there Tiaris. What I think you have missed, and I tried to explain it in my last post but not very successfully, is that all the mutations you mentioned are located at different positions in the genome. Blue and AY and WB are all different positions (i.e. different gene pairs) and therefore it is possible to have a Gould that is split to all three mutations (blue, AY and WB) simultaneously. Similarly for the head's red-black gene pair and yellow gene pair: they are also different positions in the the genome (different gene pairs), operate independently, and we can therefore have "triple splits" like red split black split yellow. Because they are all different gene pairs they can take on different modes of inheritance too (or the same). Like orange head is autosomal and red-black is sex-linked. A gene pair cannot be both sex-linked and autosomal recessive, so therefore the yellow gene pair and the red-black gene pair must be different gene pairs and different positions in the genome.

But Gould breast colour (purple, lilac, and white) is determined by a single gene pair, i.e., a single position in the genome. And because each position in the genome has a pair of genes, those two genes can only hold two of those three colours, i.e., purple and white, or lilac and lilac. They can't hold purple and white and lilac simultaneously because it is a gene pair, not a triple. Therefore, purple split lilac split white would be impossible, in my opinion. Also, because it is a single gene pair, it can only take on one mode of inheritance, i.e., purple, lilac, white, they are all autosomal because they are all expressed by the same gene pair.

Anyway that's how I understand it my own mind. I'm sometimes terrible at explaining things, so hopefully someone who has a background in genetics (I don't) can explain better and correct me where I am wrong.

Cheers
alvin

Tiaris - there were no green back hens in this aviary, 3 yellow back hens with DF green back cocks 100% purple breasted, (which will only produce green back hens and SF cocks like the one shown with the pink ring) even if there was a green back hen the nest will only have green young in it.
Green Cock x green hen - all green young
Green Cock x yellow hen - SF cocks, green hens (Parents PB) this combination was in that aviary
Yellow Cock x green hen - SF cocks , yellow hens
If white breast is in the mix, SF cocks with white breasts will be yellow backed
There were no SF cocks in this aviary, I went on to produce lots of young from this aviary, all purple breasted green back hens and SF cocks.
As I say the DF pastel blue cock must have mated with the yellow hen before I moved her that explains why 2 chicks looked like they were 2.5 weeks old and the other 2 looked like they had just hatched.
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Tiaris
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The term double-factor (DF) is exclusively used in aviculture to refer to dominant mutations not to natural forms of a bird. Using it to refer to the normal form of a species (Green-backed in the case of Gouldians) is extremely confusing to say the least.

Green hen to DF cock = SF progeny bred
Green cock to SF hen = SF cocks bred
All of my confusion regarding this stems from my initial misunderstanding that the SF young cocks you showed pics of were bred from a DF pastel cock paired to euro yellow hen as I didn't think that was possible ( only DF cocks would result). You have since clarified that The DF cock was initially also with a green hen and later that the young you initially posted about were the result of a green cock to a SF hen. Nothing unusual to produce SF cocks from either of those pairings.
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Tiaris
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Ross,
How on Earth do you know which position on the Gouldian Finch's genome, any of the genes for various known colour mutations are located, let alone determine which of certain mutations are located in different positions and others are situated in the same gene pair?
alvin

Tiaris, I don't see anything confusing about using the term DF in normal Gouldian cocks as all cocks are either DF or SF, Hens are all single factors. What do you call a green back white breast cock (which is a mutation)
You weren't the only on who said DF for that cock, its all about learning and you input is appreciated, a good debate on Gouldian topics is always good, the more guys input the merrier
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Tiaris
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I agree Alvin. I quite enjoy talking about any topic in finches. Absolutely the more the merrier.

I call a white breasted green backed Gouldian a white-breasted Gouldian.

I broadly realise the genetics at play but to use DF in reference to a normal bird is highly confusing since it is accepted common convention in aviculture to refer to DF as a double factor bird in a dominant mutation (and same applies for the use of SF for that matter too). I guess it is made more confusing when the discussion also includes references to a dominant mutation so the boundaries between forms become very fuzzy. I am not personally confused by it but many others would be since it is very unconventional to label a normal bird as a DF. Mutation genetics are a complicated enough concept to most of us as they are.
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Craig52
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I have been following this thread also and i know genetics quite well but haven't added any comments simply because of this confusion of a DF green backed cock mentioned all the time of which is impossible to have, white breasted or not so please explain from the beginning of any topic what mutations you are breeding with in laymen's terms so there is no confusion to the topic.
Cheers Craig
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