Chev, colour genes again please.
- Thread starter Wally
- Start date
Dun is dominant; I'd guess that Fjords are homozygous for dun. So they always pass along at least one dun gene.
Yup. Fjords have the same genetic base as all other breeds, but they also carry two dun genes - so they're always diluted to chestnut and dun, or bay and dun, or black and dun... 
It's the dun that's responsible for the two-tone manes in Fjords.
Bit like Haffies - they carry two chestnut and two flaxen genes - so you only ever get flaxen chestnut Hafflingers, because it's all they can pass on....
It's the dun that's responsible for the two-tone manes in Fjords. Bit like Haffies - they carry two chestnut and two flaxen genes - so you only ever get flaxen chestnut Hafflingers, because it's all they can pass on....
Um Can I just jump on the Chev and colours bandwagon, with a really basic question please? Just while there is a thread?
Sham has always had one fleck of chestnut hair in the same place on his shoulder, and now his winter coat is going there are quite a few of them appearing in one patch. Does this mean he will go fleabitten as he gets older, or would this stage have passed already considering he is now very white ( apart from some iron grey splodges around his hocks in the winter coat). Or does the fleatbitten stage come last? And........if these flecks on him are chestnut does that mean he was a chestnut foal? Or what other colours could he have been to start with, considering he must have gone totally white quite early as he is only 7 now
Thank you, no scientific reason for asking, just curious as to what my baby has looked like in the past and will look like in the future
Can I just jump on the Chev and colours bandwagon, with a really basic question please? Just while there is a thread? Sham has always had one fleck of chestnut hair in the same place on his shoulder, and now his winter coat is going there are quite a few of them appearing in one patch. Does this mean he will go fleabitten as he gets older, or would this stage have passed already considering he is now very white ( apart from some iron grey splodges around his hocks in the winter coat). Or does the fleatbitten stage come last? And........if these flecks on him are chestnut does that mean he was a chestnut foal? Or what other colours could he have been to start with, considering he must have gone totally white quite early as he is only 7 now
Thank you, no scientific reason for asking, just curious as to what my baby has looked like in the past and will look like in the future
The chestnut in Haffies is probably easier to explain - because chestnut is recessive, and horses need two red genes to be chestnut, they only have red to pass on. So breeding two chestnuts will only ever give chestnut - kind of like my Welshies.... four liver chestnut mares, if put to a chestnut stallion, would only ever produce chestnut foals - so if we were working with a very small gene pool, with a lot of chestnut in it, it becomes easier to see how a breed can become chestnut and nothing else.
Dun is a strange one... especially in Fjords where they have a full range of base colours as well. Dun is dominant, so a horse really only needs one dun gene to be dun - so it's a lot harder to see how a breed can become homozygous for a gene like that.
But.... Prezwalski's horses are all dun too, so it's not unique, and they are really as close to primitive horse as we can get - so we can assume that their colouring is also as close to 'original horse' as it's possible to go. Studies of wild horses left to breed without human intervention have shown that dun characteristics actually 'develop' even where there was no dun to begin with, showing that dun is what's called an 'atavistic' colour pattern. So... dun is, it seems, a lot more complicated than just one gene. It could be that dun is a kind of 'default' colouring, to which horses would eventually revert if left alone to breed - a kind of reversal of breeding for colour.
Perdita - fleabitten is the very last stage of greying, although not all greys go fleabitten. The freckles do tend to be of the same colour that the horse is underneath the grey - I knew a fleabitten gelding called Robbie who had dark brown flecks all over him, and he was born bay (he had so many that from a distance his body looked roan) and I think Mehitabel's Petal is fleabitten now too. May is also developing little orange flecks - not many though, and she's 11 this year, and she was completely white at 6. Not all greys do go fleabitten, some get masses of freckles, others just get a handful.
The other marking that white greys can get (especially those with Arab blood) are blood marks - big rust coloured patches usually on the shoulder. They develop after greying out is done too, and start out as small marks which get gradually bigger.
Dun is a strange one... especially in Fjords where they have a full range of base colours as well. Dun is dominant, so a horse really only needs one dun gene to be dun - so it's a lot harder to see how a breed can become homozygous for a gene like that.
But.... Prezwalski's horses are all dun too, so it's not unique, and they are really as close to primitive horse as we can get - so we can assume that their colouring is also as close to 'original horse' as it's possible to go. Studies of wild horses left to breed without human intervention have shown that dun characteristics actually 'develop' even where there was no dun to begin with, showing that dun is what's called an 'atavistic' colour pattern. So... dun is, it seems, a lot more complicated than just one gene. It could be that dun is a kind of 'default' colouring, to which horses would eventually revert if left alone to breed - a kind of reversal of breeding for colour.
Perdita - fleabitten is the very last stage of greying, although not all greys go fleabitten. The freckles do tend to be of the same colour that the horse is underneath the grey - I knew a fleabitten gelding called Robbie who had dark brown flecks all over him, and he was born bay (he had so many that from a distance his body looked roan) and I think Mehitabel's Petal is fleabitten now too. May is also developing little orange flecks - not many though, and she's 11 this year, and she was completely white at 6. Not all greys do go fleabitten, some get masses of freckles, others just get a handful.
The other marking that white greys can get (especially those with Arab blood) are blood marks - big rust coloured patches usually on the shoulder. They develop after greying out is done too, and start out as small marks which get gradually bigger.
I'll tell you one thing, Dun is by far the best camouflage. If you look at the side of a hill some way off, about a mile, where there should be 20 horses, the duns are always the last to be spotted. Sometimes you have to get out the binoculars to make sure. Sometimes they can be as close as 200 yards away and you can't see them. Maybe the "lions" eat all the other colurs?
Thank you Chev So I can pretty acuraetely imagine him as a chestnut baby then Will have to keep an eye on the flecks to see what they do
So I can pretty acuraetely imagine him as a chestnut baby then Will have to keep an eye on the flecks to see what they do
Wally said:
Could well be! It's been shown that another couple of 'primitive' types of coat pattern have the same kind of effect - countershading, which in extreme forms causes black to be mixed into the coat colour from the top down, and panagre, which causes lighter fawn areas at the flank, muzzle and belly. The two in combination are often seen in wild horses - the effect is to reverse natural shadowing, and render the horse effectively two dimensional to predators, making them really difficult to spot.
Lions picking off the more obvious horses doesn't explain how a herd made up of blacks, bays, browns and chestnuts will start to develop dun colouring after a few generations though, unless the Dun gene is not singly responsible for that coat pattern. It does seem as if it's not as simple a gene as it first appears - especially given the number of dun characteristics and the fact that they don't all appear in every dun.
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