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Eromit Labrador Retrievers
Labrador Coat Color Genetics
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EEBB
EEbb
eeBB
EEBb
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EeBB
eebb

Pigmentation refers to the color of the dogs skin, particularly on their nose and around their eyes. Black
labs always have black pigment. Chocolate Labs always have chocolate pigment. But yellow labs may
have either, depending on the alleles they carry at the B gene site.

Yellow labs with at least one Black allele will have black pigment (because it is dominant). Yellow labs
who have two b chocolate alleles will have brown pigment. They are referred to as dudley, and it is
undesirable, although it doesn't really affect them in any meaningful way outside of the show ring. Dudley
labradors will have brown squares on their nose for the purposes of the diagrams at left to denote their
brown pigment.

Carriers are dogs who 'carry' a recessive allele but do not express it themselves. In the diagrams at left,
we picture carrier dogs by having a box of a different color located in their belly. We also say that those
dogs are 'factored'. For example, the black dog at left carries chocolate - we would call him a
chocolate-factored black lab. Black labs who carry a recessive allele for each of yellow and chocolate are
called 'tri-factored' black labs. If mated correctly, they could produce any of the three colors of Labs. This
can even happen in one litter, and it is possible to predict roughly how many of each puppy will be born.
Keep reading to find out how.

The Punnett Square

The Punnett Square is a simple tool used to predict in what combinations alleles will be inherited. Let's
look at an example. Keep in mind that each puppy gets ONE allele for each gene from each parent, for a
total of two alleles for each gene.

In our example, we will breed a handsome tri-factored black lab to a yellow lab. The genotypes for each
parent would be EeBb and eeBB respectively. The first thing we need to do is figure out, for each parent,
the different combinations of alleles that could be inherited. Let's start with dad.

EeBb

Puppies could get the yellow 'off' allele paired with the Black allele ------- EB
They could get yellow 'off' paired with chocolate allele -------------------------Eb
They may end up with yellow 'on' and Black ---------------------------------------eB
or they could get yellow 'on' and choclolate ----------------------------------------eb

Mom's turn - she is yellow, with a genotype of eeBB

As you can see, there is only one possible combination of alleles from mom --------------eB

Now, we build our Punnett Square. It's like a multiplication table for geneticists. Along  the top, let's plug
in the alllele combinations that could be inherited from the stud dog. The left hand column is for the
dam's alleles.






Next, we figure out what will happen when each puppy inherits their alleles from mom and dad.










So, for this particular matchup, we will be expecting 25% Black puppies who carry yellow, 25% Black
puppies who carry yellow and chocolate, 25% yellow puppies, and 25% yellow puppies who carry
chocolate. Naturally, every litter does not come out in these exact proportions, but it does give you a good
idea of what to expected. Notice that even though the sire is tri-factored, he did not produce any chocolate
puppies because the dam does not carry a chocolate allele that can be passed down.

Click
HERE to see a  comprehensive matchup of all possible litter combinations, and their results. This
took a long time to produce, so please do not copy it onto your website. Feel free to link to our page if you
would like to show your visitors this information.



This is a link to Dr. Sheila Shmutz webpage. She is "THE" professor of coat color genetics in dogs (I was
lucky enough to study under her a few years ago). Her page talks about the coat color inheritance of
several different breeds, although it does not specifically show the charts of the labrador that we have on
Page 2.
EeBb
  EB
Eb
eB
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EeBB
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eeBB
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  EB
Eb
eB
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