Only the millionth color question

L

Lovely

Forums Enthusiast
I was reading some of the threads on here and came across one (rather rancorous, but anyway) that had a ton of genetic info on colors and how they happen. Of course, I looked at my Duncan and wondered if he is factored in any sort of way. He has a few shadows in his coat that to me look ghost-like (sort of like merling, but it would have to be from no where). Then again, if he is white-factored - couldn't he have a little extra white shading in spots? On the other end of the spectrum, he has dark tips to his puppy fur. I'm sure much of this will even as he grows into his adult coat. (Note: I have no intentions of breeding or showing - maybe just obedience or agility or something fun for a companion dog.)

So I pull out his pedigree and look for evidence of any sort of factoring, just because I'm curious. Dam and sire are sables. Okay, I knew that. Granddams and grandsires are sables. Awesome (I met one granddam on site, so I knew part of that). One more generation back, there are two tri dams only on Duncan's dam's side. And I remember that out of the 6 pups, one was a tri. To my limited knowledge of genetics, this means that both parents had to be 'Shaded' or tri-factored sables. His dam obviously is. But no tri presenting in his father's side? Then again, I didn't go but 3 gens back in the AKC pedigree.

My question is - how recessive is that tri-gene? It can't be so difficult to produce because it cropped up sort of randomly. Maybe it seems random to me because there was only one in that litter our of 6. Other litters might be different.

I think I get the merling part of genes - it is like sprinkles on ice cream. You have your basic flavors of ice cream (the base coats of shelties) and can merling 'sprinkles.' Then is white-factoring and tri-factoring like the protein mix in a healthy shake? Hidden, but still in there?

Okay, too off the wall... I suppose I'm just trying to get this all straight so my head stops going around and around the topic.

More of a discussion/general topic than a specific question. I know we have some geniuses out there!
 
Ok, I'm no genius but let's go over some basics.

DNA, the code book of how we are designed, is 50% from mom and 50% from dad. The genes that stack up to make your DNA are in pairs; the process that matures an egg or a sperm basically splits gene pairs - like unzipping a zipper; so that its ready to zip to its new partner to make a brand new individual.

To keep coat color simple is a bit impossible; because you have to juggle data that decides basic coat color, merling, ticking, spotting, white factoring......and there are probably more items that science hasn't identified yet. But in a boiled down version:

There are two basic coat colors: black or sable.
Black is subdivided into two types: trifactored black or bifactored black
Sable is a dominant color. If a pup has ONE gene for sable it will be sable.
Black is recessive, and bi-black is the most recessive of the recessive.

So a sable parent may have genes that are sable-sable OR sable-trifactor OR sable-bifactor; they will still be sable although a lot of sables that carry a gene for black will be "shaded" sables i.e. they'll have a black or dark brown hairs overlaying the sable undercoat.

A Tricolor parent has genes that are either trifactor-trifactor OR trifactor-bifactored.

A Bi-black parent's genes are Bifactor-bifactor. That's it. No other choices. The most recessive of the colors. :biggrin2:

Now for all the ones screaming about the merle coat color...its not a base coat color. Its a modifier ON the gene (sort of like how positive or negative is a modifier on the A or B of your blood type). Anyway, the merle is a modifier to the base coat. If the dog is a black dog; it turns it into a merle. Trifactored blacks become Merles with tan points; Bifactored blacks become Bi-blue merles. The merle gene does not strongly affect the sable color as this gene is VERY dominant; so a sable dog can successfully carry a merle modifier without ever showing one hair that is different. Additionally; sometimes a black dog will show very little of the merle factor and is known as a "cryptic merle".

White factoring is also a coat modifier. This doesn't refer to the white tips on the tail and paws and collar (that's known as Irish marking for some reason and is a different coat modifier). White factoring will bring on spots on the back or a white edge along the back leg. If both parents contribute the white factoring modifier to a pup you get....a color-headed white. The body will be predominantly white, and only the head will show the base color of the dog.

There are other coat modifiers for freckles, ticking, spotting, etc. They are less well known. The main ones to follow are the ones listed above.

So, how recessive is the tri-factoring? The same as blue eyes in human. Two blue-eyed humans will always have blue-eyed children. But blue is recessive to brown; so two brown-eyed parents can have blue-eyed children IF each parent has the gene code for Brown-blue Brown-blue.

Your pup could be sable-sable OR sable-trifactor.....or lets' face it sable-bi-black. I got the big surprise with Emma's first litter of pups as I was expecting sables, tricolors, or merles....not bi-blacks. Each of Emma's litters has had one bi-black; which means both Emma and Figgy carry the super-recessive bi-black gene.
 
I get the very basics of genetics. While I like Chem much better than Biology, I understand the necessity.

And the blue eyed thing works very well. I have blue eyes - neither parent does (dad has brown, mother has hazel). The closest relatives (in my 'pedigree' - hehe) that have the eyes are my maternal great grandmother and my paternal grandmother. One on each side, the recessive sticks around... and viola! Kid with blue eyes. (I'm just hoping that my hubby's dark brown eyes don't overwhelm my recessiveness too much - I think we have something like a 38.5% chance of having a blue eyed child since he has sisters with blue eyes and might carry the recessive.)

I decided to go back (in my head) to high school Biology. Ah, Punnett squares!!
Here is a calculator:
http://www.changbioscience.com/genetics/punnett.html

This uses the genotype (what the genes say) as opposed to come calculator that use only phenotype (what shows up). I think I was playing around too much with the phenotyped (well, largely) on http://www.athro.com/sheltie.html - it is a nice site, but forgets about things like a cryptic merle.

Start with pure sable (no shading). This is dominant, so say AA (using the Punnett square calculator). You cross two of them and you can only get AA back.
Aa would be a shaded sable (ignoring tri or bi here). You can get back AA (25%), Aa (50%), and aa (25%). If the little a is tri- that explains my question above - both sable parents were shaded, therefore they have a 25% chance of tris in their litters. This litter was only 6. I'd have to consult my breeder to see about previous litters colors. (And Duncan's aunt, who is bred with the same stud.)
As you can see from the site - you can add more letters and get more combinations. The first letter determines phenotype (capital - sable, lower case - tri- or bi, depending on the factoring of the parents).

Correct me if any of this is wrong. I had to take a deep breath and try to remember all I could about and putz around on the net for a bit to get it settled in my head.
 
I can tell you, that I had the bi-black gene express 4 generations down- like this, going backwards in time- lol
here is how it played out-


Grace- bi-black (my litter I bred)


Charm-(her mother- my litter I bred) sable


Grady- (her grandfather- my dog- I purchased) tri


Apollo- (her great-grandfather-dog I saw myself) tri


Cindy-(her great great grandmother-listed on akc ped.) bi-black





so now of course, I know that Charm is bi-factored :smile2:
 
Ouch. My head hurts :dead:

Just out of curiousity. Are my two boy tri-factored sables? They're sable but they have black, not sure of the correct term. Basically, the ends of their hair is black.

Take a look at some of my photos if you need to. I'm just curious. I love the coloring (even though originally, I wanted the "typical" sable). I love how the color changes over time.

Thanks.
 
To me, your dogs look like they are tri-factored sables. If you want to see Pure-for-sable coloring, go to my albumn. All of our dogs are pure-for sable. I just happen to like the really red coloring, and I guess you would say we are known for really red dogs.....thank you Mark!
 
missjen,

See, to me, I wouldn't think they're pure sable, as they have black in their coats. Although, they are VERY beautiful coats. Maybe I'm mistaking what I see for what I think their genetic are, lol.

I guess when I think sable, I think, gawd help me we know I'm not about to say it.........."Lassie". AKA a dog who's mostly only the sable color.
Lassie Picture

Thanks though, for letting me know my pups may be trifactored. I should just look at his pedigree. ;)
 
You must log in or register to reply here.
Back
Top