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Post by Jessica on Jul 28, 2013 20:51:16 GMT
Hoping some of you lovely knowledgeable people can help! I'm trying to figure out how the dun gene takes affect. Having read the following: en.wikipedia.org/wiki/Dun_geneLooking at the "breeding and the dun gene" section it gives three combinations rather than just two. Does that mean it is not part of the normal colouring genes passed on, but is inherited on say a different chromosome and acts on the colour? For example it says chestnut + dun + cream = palomino dun. The pony that I am trying to work out the genetics of is as follows:  If the pony is Buckskin not dun am I correct in thinking that it cannot be by a chestnut?! |
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sarahp
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Post by sarahp on Jul 28, 2013 21:46:34 GMT
Well to give you an answer would require more definition of your terms. First, do you mean dun or buckskin? They are genetically distinct colours. Buckskin is bay with one copy of the cream dilution gene, whereas dun is a singe dominant which can act on any base colour, and is most commonly found in the northern breeds of native pony, ie Highlands, Shetlands, Fjords and Icelandics. Second, are you using cream for a palomino or a double dilute with cream coat, pink skin and blue eyes - which is a double dilute wjereas palomino is single. Third - cream dun? Fourth - I would assume that grey/black is in fact a pony in the process of greying out.
I will try to explain when I have the answers to these questions!
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Post by Jessica on Jul 28, 2013 21:53:02 GMT
Well to give you an answer would require more definition of your terms. First, do you mean dun or buckskin? They are genetically distinct colours. Buckskin is bay with one copy of the cream dilution gene, whereas dun is a singe dominant which can act on any base colour, and is most commonly found in the northern breeds of native pony, ie Highlands, Shetlands, Fjords and Icelandics. Second, are you using cream for a palomino or a double dilute with cream coat, pink skin and blue eyes - which is a double dilute wjereas palomino is single. Third - cream dun? Fourth - I would assume that grey/black is in fact a pony in the process of greying out. I will try to explain when I have the answers to these questions! Colours are exactly as written on the pedigree I have. I understand the genetics for a buckskin, it is the dun that I am trying to get my head round. To my mind this pony should have got the cream dilute from the dam, but where would the bay come from as sire is chestnut. Hence wondering if the dun influence was at play here? |
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Post by leevale on Jul 29, 2013 7:15:23 GMT
The foal is likely to be a buckskin assuming one parent was chestnut and the other perlino. The only way to tell for certain is to have the pony DNA tested.  |
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Post by Jessica on Jul 29, 2013 7:31:52 GMT
Unfortunately he isn't mine to DNA test! I thought chestnut and Perlino would give a palomino? And only bay and dilute a buckskin?
Sarah, looking at photos and what she produced I would say the mare is one dilute, one grey.
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sarahp
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Post by sarahp on Jul 29, 2013 8:06:16 GMT
Wonderful example of the confusion caused when the wrong terms are used. We were not allowed to quote wikipaedia when I was at College but had to go back to original sources, there are many colour genetics articles that would explain it all in a clearer way than apparently wikipaedia has for you.
If this pony is Welsh it is very very unlikely that it has dun at all, but that what is called "dun" on the pedigree is actually buckskin. Working on this assumption, if the so-called "cream" (which is not a proper genetic description of any horse colour anyway) dam is actually a perlino, which is a cream coated, pink skinned, blue-eyed pony that is genetically a bay that carries two copies of the cream dilution gene, that is where the black and agouti will have come from to produce the buckskin offspring. For the dam to be perlino it would require both of her parents to carry one copy of cream dilute, easily hidden beneath grey, and if her "dun" sire is actually buckskin he would carry one too. If the dam is actually dark skinned grey then she would have to be buckskin underneath the grey, again possible from the pedigree, and in that case perhaps registered cream as a foal when there was little black showing - grey with dilute does turn up some weird foal colours before they show the true colour.
On the other hand, if the "dun"s are actually duns (perhaps this is a Shetland) the "cream" dam would have to be a dun too as it is a single dominant that acts on all base colours as I explained above, and again has been misdescribed.
To answer your direct question - Chestnut + dun + cream dilute will give you a palomino dun, sometimes called a dunalino. Two separate genes, those for red/black and agouti, give every horse a base colour, and other modifying genes act on that, which can be in any combination although different breeds do have different modifiers within the breed, governed by breed regulations. So chestnut with cream dilute will produce a palomino, and with dun too the dun colour pattern will be superimposed onto the palomino to give a palomino dun.
I hope you can understand why I asked for more information before embarking on all this!
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Post by Jessica on Jul 29, 2013 12:23:16 GMT
So if I have got the right end of the stick, a horse will inherit 2 normal colour genes (one from each parent) ie. chestnut, bay; potentially 2 dilute genes (one from each parent); and potentially 2 "dun genes"? and hence this pony is buckskin but could carry a chestnut gene? And a palomino is then chestnut + chestnut + dilute? A cremello, chestnut + chestnut + dilute + dilute?
Sorry for all the questions!
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sarahp
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Post by sarahp on Jul 29, 2013 17:40:36 GMT
Starting from scratch. Individual genes occur in pairs, one from each parent. Homozygous means there are two copies of a gene, heterozygous that the two copies are different. One gene codes for red or black chestnut - to actually be a chestnut the pony must carry two copies of it, otherwise it will be black based, but if heterozygous will carry a gene for chestnut. Another, agouti, restricts the black pigment, if carried, to the points ie the pony will be bay and not black. Thus a chestnut can carry agouti without it showing. Having sorted the base colour with these two genes, it may or may not be modified by other genes working on top of it. Minor ones I won't bother about can affect it but ignore those for the moment.
A chestnut with one copy of the cream dilute gene (the other of the pair will only be "non-dilute") will be palomino, a chestnut with two copies will be cremello. A bay with one copy will be buckskin, with two copies will be perlino. A Black with one copy will be dilute (smokey) black, a black with two copies will be smokey cream. All the double dilutes will have cream coat, pink skin and blue eyes.
Dun is a totally different colour genetically.
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Post by Jessica on Jul 29, 2013 22:02:39 GMT
That's brilliant, thank you so much!
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sarahp
Happy to help
Posts: 9,510
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Post by sarahp on Jul 30, 2013 6:04:30 GMT
You're welcome.
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