Color Genetics

[Tanya]

I realize color genetics in labs can be a tad complicated (ok - VERY complicated) but I've been wondering

But how do these so called "white lab" breeders gets so many lights colored labs in each litter? OR a fox red "breeder" get so many very dark labs?

If you throw two very light colored labs together do you end up with a higher proportion of light colored pups? do you just keep repeating that? (same with the dark colored ones)?

This reminds me of a friend who said they know a beagle breeder that takes ANY beagle with the "rare" coloring (no black) and breeds them. He does this over and over finding all of these "rare" dogs he can simply because so many people request these "special" beagles. This breaks my heart - he obviously doesn't care about the health of the breed and is doing a great disservice by introducing (most likely) so many bad genetics in this already limited color.

[Trickster]

Interesting question. I hope one of the breeders will come along and enlighten us.

[JacksAndLabs]

http://www.labbies.com/genetics2.htm#Yellow_Model

Basically, the "E" allele decides whether the dog is yellow or not. A and C code for which shade.

[FieldLabLover]

That's essentially what they do is look for a white or Fox Red mate. Unfortunately, they are ignoring all other traits to get the shade they want so they can sell it for more (they think).

[Bob Pr.]

JacksandLab, thanks for posting that link to Pamela Davol's article.* This one is at least the third or fourth revision she's made and I like it much better than her previous edition and not quite as well as her first on this extremely complex topic.

Her first article (maybe 3-4? years ago) on the variations in shading in yellow Labs (and also some variation in chocolates) put heavy emphasis on some epistatic (modifier) genes.* The effects of such genes vary in accordance with variations in physical properties, such as temperature, surrounding medium, or presence of others, etc.* That is, for example, as temperatures change, the effect of certain genes change.* While most genes are not (as far as we know) epistatic, some obviously are.*

But temperature variation is not the only thing that can affect epistatic genes and, in turn, their effect on the organism.* Some species of plants have one form if they grow on land above water but a completely* different form and leaf shape when grown below water in a stream bed.* Individuals of some species of fish change gender from female (the more usual) to male (less common) when there are not enough males in the environment.

In the case of yellow Labs, she said (in her first version) that some of these epistatic (modifier) genes are influenced by temperature.* For cooler body parts, they'll produce darker colors, while warmer body parts will be lighter in color.

I REALLY LIKED THAT EXPLANATION.* It perfectly explained my medium-dark YF, Puff's --
-- darker ears
-- her light throat
-- lighter "angel wings" (just to the rear of her denser shoulders)
-- the darker streak down her back (heat blocked by the spine), the top of and TIP of her tail,
-- darker areas along the back of her hind legs where there's little flesh
-- the lighter fur of her belly
-- and the white fur of her buttocks

So I'm happy to see that in THIS version she brings back the modification of gene expression due to body heat for one or two of the eight or so genes determining darkness-lightness of coat color.

As reading this article makes clear, while a great deal is known now, the final answers wait on results from the dog genome project.

[WigWag]

Fifty years ago yellows were medium to dark in color. Fox reds have always been around and this is the work of some other genes (C gene) that encodes for a deeper shade of yellow in conjunction with the E gene. So fox red X fox red breedings will yield mostly fox reds. Also a fox red bred to a medium to dark yellow will also yield more fox reds. Now back to yellow. Over the years the paler cream yellows have gained favor and so yes simply by selecting them they have become more popular. Some dogs are dominant for the light color. My girl Scout is very light - nearly white and her father was black but produced yellow dogs and ALL yellow dogs produced by him are very light in color. He was dominant for that shade. Most of their offpsring are light as well. Many times litters have a variety of shading if several yellows are present. When I bred my very light girl to my black boy I had five yellows in the litter and all were different in color - one nearly white, three medium, and one a little darker. I know of another popular stud dog who is dominant for throwing medium to dark yellows - I call that "a lot of color".

[WigWag]

This reminds me of a friend who said they know a beagle breeder that takes ANY beagle with the "rare" coloring (no black) and breeds them. He does this over and over finding all of these "rare" dogs he can simply because so many people request these "special" beagles. This breaks my heart - he obviously doesn't care about the health of the breed and is doing a great disservice by introducing (most likely) so many bad genetics in this already limited color.

Orange and white and lemon and white (orange with chocolate pigment) are not rare colors in Beagles. They can be tricolor (orange and black and white) and also orange and lemon and white and can be bred together to yield different colors in a litter. Your friend doesn't know what he is talking about.

[Tanya]

I read the link quickly - it certainly answers my question! so if someone wants to mass produce these color "extremes" they can do so. I'll have to re-read it for a better understand though!
thank you very much everyone!

Orange and white and lemon and white (orange with chocolate pigment) are not rare colors in Beagles. They can be tricolor (orange and black and white) and also orange and lemon and white and can be bred together to yield different colors in a litter. Your friend doesn't know what he is talking about.

LOL! Trust me - I whole heartedly agree with your comment Great person, but one that has done no research at all on dogs (and joy of joy - they plan to bread their beagle : )
I was using the term "rare" lightly though, I realize it's common, it just doesn't happen as often (in the particular "breeder's" stock.

[CaliforniaLabLover]

In the case of yellow Labs, she said (in her first version) that some of these epistatic (modifier) genes are influenced by temperature.* For cooler body parts, they'll produce darker colors, while warmer body parts will be lighter in color.

That's interesting. The same type of theory as behind the "pointed" colors of cats, like in the siamese or ragdoll breeds.

[jaybird]

My dogs are fixed but I wondered if you breed 2 chocolates. Is there chance to get another color. I know this belongs in the stupid people forum probably.