DNA questions....Genotypes questions....
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Thread: DNA questions....Genotypes questions....

  1. #1
    Join Date
    Feb 2008
    Posts
    8

    DefaultDNA questions....Genotypes questions....

    I need some help understanding coat color genetics before purchasing an expensive Labrador puppy. I am wondering if you could assist me.

    I have just been introduced to a very gorgeous litter of pups, which some are show prospects. According to the breeder, his black Labrador (all black, no white patches) gave birth to 10 pups total…

    6 Blacks (1 died at birth, undeveloped, too small) (60% Black)
    1 Chocolate (10% Chocolate)
    3 Yellows (2 w/black noses, 1 with pigment lacking in nose) (30% Yellow)

    The breeder showed me the sire who is a yellow lab (black nose and eye rims).

    After researching genotypes I don't understand how this litter can be produced from these parents. I am assuming the black mother is BbEe, given how she produced a chocolate pup and yellows in the litter. I assume also that the sire is eeBb, given how he is yellow, with black eye rims and nose and the litter has a chocolate pup, black pups and yellow pups. But according to this combination, it doesn't seem possible to have 60% of the litter be black. Or am I misunderstanding?

    If going by another website's info, it shows the outcome to be as follows for these dogs.

    EeBb(black/yellow & choc carrier) X eeBb(yellow/black & choc carrier) = genotype: 1/8 EeBB + 1/4 EeBb + 1/8 eeBB + 1/4 eeBb + 1/8 eebb + 1/8 Eebb---phenotype: 50% yellow pups + 38% black pups + 12% choc pups

    I saw the litter, I saw that mother, but is she really the mother and is he really the father? If not, who could be the mother and father that would be able to produce this litter?

    Can you help me to determine what type the parents would be with a litter of these colors? I am very confused, IF this is in fact true that both parents are who the breeder says they are.

    How can we be absolutely sure the parents are who they say they are without DNA even if both parents are AKC registered?

    Thanks!

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  3. #2
    Join Date
    Apr 2009
    Posts
    2,559

    DefaultRe: DNA questions....Genotypes questions....

    Well, its not unusal, you have to keep in mind that these are percentages like flipping a coin.

    Each coin toss has a chance of being heads or tails. If you flip the coin seven times in a row and get all tails, those flips have nothing to do with the next toss. The odds are still 50% heads and 50% tails. You might get tails 14 times in a row before a heads, but out of one hundred tosses, you will get more even data.

    Same goes for those puppies. Each puppy had a chance to be black, yellow or chocolate. Black is dominant over yellow and chocolate, so if mom gives her black gene, you will have a black puppy regardless of what dad is contributing.

    She could just as easily had an all yellow litter, or more chocolates then black, it just depends on which sperm and egg was in the right place at the right time.

    All odds go out the window.

    My Rhys was from a By bitch to a By male, 10 puppies, all yellow. Exlain the odds on that one

  4. #3
    Bob Pr. is offline Senior Member
    Join Date
    Feb 2009
    Location
    Lawrence (ex-Topeka), KS
    Posts
    8,472

    DefaultRe: DNA questions....Genotypes questions....

    You've mastered some understanding of Lab coat color genetics that many Lab owners find difficult to understand. Congratulations.

    But your problem is that you're trying to apply the theoretical statistical probability of approximately what one would expect to get from thousands of matings between 2 parents with that genotype to the outcome of this single litter.

    The distribution you saw is a reasonable one for those parents.

    Those 2 parents could have had all yellow, all black, or all chocolate, depending on which of the sperm met with which of the eggs.
    Puff [YF, AKC field line (from competing HT/FT breeder) 62 lbs, dob: 8-'01]

    Bess [BF, AKC bench line (from competing show breeder) 55 lbs., 1967-1981] "Poor Bess, the Wonder Dog":
    http://forum.justlabradors.com/showt...?p=748#post748

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