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Thread: Silver Labs?

  1. #151
    Senior Member copterdoc's Avatar
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    Pseudoscience ain't Science.

    They are ALL scams.

  2. #152
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    Quote Originally Posted by copterdoc View Post
    ALL breeds of dogs were created from other breeds of dogs.

    Every single one of them.

    A breed is "complete" when we have selectively removed ALL of the Recessive Alleles and/or ALL of the Dominant Alleles from specific Loci in the dogs that fall within the registry.

    That way, it's not possible for two dogs within the registry to produce offspring that express a Dominant or Recessive trait that is not found within the breed.

    No matter what two dogs are bred within the registry, you will never spontaneously produce a Recessive, or Dominant Allele, where neither Parent has one.

    These traits are not found within a breed, for the simple reason that they were intentionally removed from the breed.
    I don't know squat about genetics or breeding but I do question how this could have been done considering breeds were created over a hundred years ago when they didn't know what DNA was. This "silver" gene was obviously in the wolf from which all dogs derive. How could they say FOR CERTAIN that there was not a single Labradoe that carried it?

  3. #153
    Senior Member copterdoc's Avatar
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    Quote Originally Posted by gdluck View Post
    ....How could they say FOR CERTAIN that there was not a single Labradoe that carried it?
    They couldn't. And they still can't.

    That's why when they produce something "weird", that doesn't fall within the breed standard, reputable and responsible breeders don't keep intentionally reproducing it "under the radar" of the breed's Parent Club.

    THEY STOP PRODUCING IT.
    Last edited by copterdoc; 01-27-2014 at 01:14 PM.

  4. #154
    Member Jere's Avatar
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    Quote Originally Posted by copterdoc View Post
    ALL breeds of dogs were created from other breeds of dogs.

    Every single one of them.

    A breed is "complete" when we have selectively removed ALL of the Recessive Alleles and/or ALL of the Dominant Alleles from specific Loci in the dogs that fall within the registry.

    That way, it's not possible for two dogs within the registry to produce offspring that express a Dominant or Recessive trait that is not found within the breed.

    No matter what two dogs are bred within the registry, you will never spontaneously produce a Recessive, or Dominant Allele, where neither Parent has one.

    These traits are not found within a breed, for the simple reason that they were intentionally removed from the breed.

    First bolded: This is an extreme position not present in the rules of any registry I've heard of. Would you provide reference, please? One might even suggest, since dogs in general share such a high percentage of genes, you're nearly insisting on a "breed" be a collection of clones derived from the general dog population by evolution by artificial selective breeding. I will say this with essentially complete certainty. No breed on the planet satisfies your criteria.

    Second bolded: Apparently you have not heard of mutations? One characteristic of a "breed" is that it "breed true." i.e. breeding within the breed population produces no (or very few?) phenotypically non-conforming offspring. I suspect one could define Black Labrador retriever breed as being BBEE black (not BbEE, or BBEe) (in fact I know at least one rather successful Lab field champion owner who insists on this) should one so desire. But over time one is certain to find yellows and chocolates produced as result of mutations the breeding program can not control. If you push this argument far enough - to the point a breed IS a population of essential clones, there is no way to "improve the breed", gain higher performance for instance, by selectively breeding within the population because there is no variation to select from.

    Jere

  5. #155
    Senior Member copterdoc's Avatar
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    Quote Originally Posted by Jere View Post
    Would you provide reference, please?
    I don't need to.
    The answer is self evident.

    If there are random Recessive and Dominant Alleles available in the Loci that DEFINE the breed, there is no such thing as a breed.

    These dogs of specific breeds do not produce clones of themselves, because among the thousands and thousands of Loci that do not define the breed, there is plenty of genetic diversity.

    While it is theoretically possible for a mutation to randomly occur, it's infinitely less likely that a EE dog produced an ee pup, than it is that there was simply a "fox in the henhouse".

  6. #156
    Senior Member afdahl's Avatar
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    In addition to Jere's nice, clear explanations let me point out that, prior to DNA testing, it was not feasible to breed out an unwanted recessive. As the incidence gets lower and lower in a population, carriers are bred to one another more and more rarely. "Affecteds" or double-recessives almost never show up. It would be possible to maintain a few affecteds to use in test crosses, but test crosses are subject to statistics, meaning that a single test cross gives only a probability, never a certainty, that the parent in question is homozygous dominant. You can increase that probability with more test crosses, but taken to extremes an animal's whole reproductive life would be taken up with test crosses. You have the expense of breeding plus all of the unwanted, known carriers to dispose of--all for something so rare it effectively never crops up anyway. Breeders are going to put their effort into some of the other, many traits that are important to the quality of the animal and the definition of the breed.

    Amy DAhl

  7. #157
    Senior Member afdahl's Avatar
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    Oh, and just for fun--back when I was researching my color genetics articles, I believe I found a paper that concluded that Labrador E is a mutation of e. Neither one is the wild-type allele. Because of the nature of the protein coded for, mutations occur relatively readily, which is why we see so many mosaics. Well, that and the Internet!

    Amy Dahl

  8. #158
    Senior Member mitty's Avatar
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    When I was a kid I had pet gerbils. They were all agouti color---your basic brown. That's all there was back then.

    A generation later, I go to the pet store to get my child a gerbil. Guess what, gerbils come in all shades nowadays. Black, white with black skin, fox red, black and white, all kinds of pretty colors to choose from. Some had long hair, some had short hair.

    I was amazed. I am guessing that the genes for all this variation were present in the gerbil population of 1970, and that through selective breeding the new varieties appeared.

    Could something similar have happened in Labrador retrievers? That the variant was present but very rare, and through selective breeding became more common? I don't think so, but never say never.

    The mutation that causes the dilute coat color appears to be the same in all breeds of dogs, and appears to have existed prior to the domestication(s) of dogs (http://jhered.oxfordjournals.org/con...pl_1/S75.short). It is unlikely that the mutation causing the silver coat color in labradors appeared after the breed was established.
    Last edited by mitty; 01-27-2014 at 04:16 PM.
    Renee P

  9. #159
    Senior Member afdahl's Avatar
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    Quote Originally Posted by mitty View Post
    When I was a kid I had pet gerbils. They were all agouti color---your basic brown. That's all there was back then.

    A generation later, I go to the pet store to get my child a gerbil. Guess what, gerbils come in all shades nowadays. Black, white with black skin, fox red, black and white, all kinds of pretty colors to choose from. Some had long hair, some had short hair.

    I was amazed. I am guessing that the genes for all this variation were present in the gerbil population of 1970, and that through selective breeding the new varieties appeared.

    Could something similar have happened in Labrador retrievers? That the variant was present but very rare, and through selective breeding became more common? I don't think so, but never say never.

    The mutation that causes the dilute coat color appears to be the same in all breeds of dogs, and appears to have existed prior to the domestication(s) of dogs (http://jhered.oxfordjournals.org/con...pl_1/S75.short). It is unlikely that the mutation causing the silver coat color in labradors appeared after the breed was established.
    I think that experiment with the Russian fur foxes is instructive. They rerun a documentary every so often--can't remember if it's Nova or what show, but look out for it. The key point is that the researchers began selecting one group of foxes for minimum aggression and fear toward humans, and another group for maximum fear and aggression. The one group eventually became quite tame, like domestic dogs--and with the tameness, a bunch of other traits showed up: splashes of white, other colors never before seen (and this was a population that had been bred in captivity for many generations), lop ears, curly tails. Someone on the show expressed the opinion that selection for "tameness" seemed to promote a tendency for mutations to occur in these other traits. I infer, but am not certain, that they ruled out the possibility that greater inbreeding in the tame group was causing rare recessives to surface (of course in dogs, lop ears are dominant, so the gene wouldn't be hidden).

    The takeaway is that perhaps all of these traits weren't present in the ancestral wolf population, but are a by-product of domestication and somehow associated with the loss of fear. Interesting stuff.

    Amy Dahl

  10. #160
    Senior Member mitty's Avatar
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    Quote Originally Posted by afdahl View Post
    I think that experiment with the Russian fur foxes is instructive. They rerun a documentary every so often--can't remember if it's Nova or what show, but look out for it. The key point is that the researchers began selecting one group of foxes for minimum aggression and fear toward humans, and another group for maximum fear and aggression. The one group eventually became quite tame, like domestic dogs--and with the tameness, a bunch of other traits showed up: splashes of white, other colors never before seen (and this was a population that had been bred in captivity for many generations), lop ears, curly tails. Someone on the show expressed the opinion that selection for "tameness" seemed to promote a tendency for mutations to occur in these other traits. I infer, but am not certain, that they ruled out the possibility that greater inbreeding in the tame group was causing rare recessives to surface (of course in dogs, lop ears are dominant, so the gene wouldn't be hidden).

    The takeaway is that perhaps all of these traits weren't present in the ancestral wolf population, but are a by-product of domestication and somehow associated with the loss of fear. Interesting stuff.

    Amy Dahl
    I love the fox experiment! I thought of slapping this up before:

    http://www.americanscientist.org/iss...age=3&css=prin
    Last edited by mitty; 01-27-2014 at 04:53 PM.
    Renee P

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