Colour genetics question?

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S_N

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If you breed a homozygous coloured, to a homozygous spotty, what colour do you get?

You can thank zebedee for this question, as it was talking to her the other night that's made me think of this!
 
Confused?
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(sorry not helpful!)
 
The gene for Tobianos (coloured) seems to be dominant - so you'd expect to get a coloured foal....

The spotted seem to be caused by a sabino gene but seems to be recessive, so would need two of them to have a spotted foal.

Some info here:
http://www.vgl.ucdavis.edu/~lvmillon/

DISCLAIMER This is all just me googling and being curious though - I'm not a geneticist!
 
Hmmm... I am saying coloured with with some spotty like characteristics (there is one I am thinking of on the yard I am on, and he is absolutely beautiful. He is a coloured but on his bottom he has the most beautiful spotty markings)
 
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Hmmm... I am saying coloured with with some spotty like characteristics (there is one I am thinking of on the yard I am on, and he is absolutely beautiful. He is a coloured but on his bottom he has the most beautiful spotty markings)

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OOooo PICTURES!!!!
 
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Um probably very stupid answer as I know very little about this but

can you get homozygous mares?

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Why ever could you not? I have no idea - surely you can. Anyone??
 
Ignore my last post - further googling has revealed that the appaloosa colour is also caused by a dominant gene, so I think PF and Becki could be right and you'd get a mongrel.

http://www.reining-appaloosa.com/PuzzleWorthSolving.htm

"A homozygous Appaloosa (LPLP) will produce offspring with Appaloosa colouring and/or characteristics 100% of the time, regardless of the breed it is crossed"
 
Ahh well that answers that one then!

I guess we never hear of mares that are homozygous, as many people may not know..... After all it's a big selling point for a coloured stallion as a stud, if he is guaranteed to pass on his colouring.
 
Homozygous means the horse carries two copies of the gene and so will pass at least one of them on to the offspring

if the gene in question is dominant, then the phenotype will follow the genotype - that is, the offspring will exhibit the colour

Tobiano and appaloosa are BOTH dominant genes, on different alleles, so you'd get a pintaloosa or appiano - which both mean the same thing - a horse with spots and splashes of colour - the base colour depending on the base colour genetics of the two parents. In practise, it's a mess because you end up with mostly white with mottled patches. Personally, I wouldn't do it.

and yes, homozygous horses can be mares or stallions (or geldings, if you cut them)

E
 
Brilliant - thank you!! It's all flooding back to me now - it's amazing what you forget as soon as you sit the exam eh!

Whereabouts in Shrops are you? I lived up there for a LOOOOOONNNGGGGG time!!
 
Apologies for a slight hijack here... but is there a sure way of telling if a particular colour is homozygous?

There is a stallion I may use on my mare, now she's chestnut, he's a British Appaloosa chestnut leopard...

This is him...

So what are the colours I could get? Is it 100% it would be chestnut but not 100% that it would spot out?

Also, I did look at an arab stallion who they say is a homozygous black, but when I looked on the colour predictor thingy - it came up that a homozygous black stallion on a chestnut mare would NOT be 100% black foal, it would be 50% black, 50% bay!

Help please? Cheers!
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I believe it is done from a blood test...... maybe a hair analysis for DNA or some such.... Not much help am I. Why don't you google Goshka Ringo (only homozygous stallion I can think of) and contact them and ask them how they found out?
 
SOME colours have a form which is different in the homozygous form... appaloosa is one of these - the homozygous form is called 'FEW SPOT' and is phenotypically quite distinct

so - your mare is chestnut which is recessive to everything, so if she is exhibiting chestnut, she's not carrying any other genes EXCEPT it's possible for a chestnut horse to carry bay: Bay is a modifier gene which limts the black of a black horse to the points - so a bay horse is a black horse with an extra gene that restricts the colour to mane, tail and lower limbs.

A chestnut horse MIGHT carry bay, but not show it because there's no black to be restricted.

The chestnut appaloosa is, by definition, heterozygous - all leopart spot appaloosa's carry ONE gene for spots and one for NO Spots.

His base colour is chestnut - so no other colours there

so if you cross him with your mare, the foal will get

From the mare chestnut - nothing else

from the horse - EITHER chestnut WITH spots or Chestnut WITHOUT spots

so you have a 50:50 chance of having a foal which exhibits appaloosa characteristics (which may be restricted to stripes on the foot and mottled sclera, all the way to full leopart spot)

and a 50:50 chance of having a plain chestnut foal

so - the rule of thumb is - if the stallion was a chestnut, would you still use him? Has he the conformation, temperament and performance abilities you want because there's a one in two chance your foal will end up chestnut.

E
 
Yes I'd still use him as he ticks all the boxes, and for a foal, I love gingers anyway and spots would just be a bonus!

With the black stallion... not sure if it makes any difference anyway but my mares mum was a chestnut, and her sire was grey. Does this make any difference to the black/bay link? I know we had 50/50 with her whether she was grey or chestnut and she turned out chestnut with flaxen bits in mane and tail...
 
You'd never be able to tell - the grey might carry the bay gene but it's hard to see - the bay/grey horses have blacker manes and tails, but he could as easily have been a chestnut/grey or brown or black and you'd not see anything but grey. And chestnut might carry bay for generations and not show it - so with chestnut (may be homozygous or heterozygous for bay, or not carry it at all) x black, you'll either get black if there's no bay gene or a chance of bay if there is. The only way to tell would be test matings, which are not necessarily a useful or practical thing to do

E
 
It pretty much put me off the black as he's AI and not cheap and if I was using a homozygous black I'd be gutted to get a bay...

Whereas I'd be totally happy with a 3rd generation chestnut, and it wouldn't really bother me if it didn't spot out, though would be a lovely plus if it did!

Otherwise there is another stallion locally that ticks most boxes, a tri-coloured (bay black and white) and again, colour isn't the issue there - he just is the right type...

Apologies again for the hijack but I love this stuff!!!
 
I have a homozygous mare and a homozygous 2 year old colt - both will guarantee coloured foals...so yes you can definitely get homozygous mares!!

Re the original question - I also have a homozygous spotted (Few spot they are called) mare and colt...if I was to cross the 2 I'd get something with spots and splodges - it's that simple and that vague - there would be tobiano and spotted characteristics when can either look an absolute mess or a bit different! I'm not taking the risk on the absolute mess front though so won't be crossing the two!

They even have names - Appiano and Pintaloosa I think both describe horses with coloured and spotty characteristics...
 
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