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Recessives - Pheno - Geno
Type - What is that???
Knowing a little about these terms will give
you a major head start on accurately predicting your litters. Let's define
them:
A Recessive is a gene that must be carried
in double dose in order to be visually seen. This means that because a
puppy inherits one of each color genes from each parent, both parents
must carry and pass to the pup the same recessive gene in order for the
offspring to get a double dose of it and show it visibly. Every newborn
puppy could carry one of these genes from each parent but will not show
the color visibly if it is in single dose, but when bred to a dog that
carries the recessive genesome of the offspring will be that particular
color.
If a dog carries two genes that are the same,
it is called being Homozygous for that gene.
If he carries two genes that are not the same
he is said to be Heterozygous.
Phenotype is what the dog's visual genetic
makeup appears to be.
Genotype is what the true genetic makeup
of the dog is whether he visually shows the traits or not. Dominant
genes produce the same phenotype whether they are paired with an identical
or dissimilar gene. Recessive genes can be hidden or masked by a dominant
gene.
Knowing a little
about the Loci and alleles we can explain some of the terms using examples:
(click
here if you have not read the section Knowing Your Dogs Genetics)
Let's take a black dog that is Homozygous for
(DD). Meaning that it carries two genes of the same allele at a Loci. When
you breed that dog to another dog Homozygous for (DD) you will get a whole
litter of black dogs provided the dogs do not carry a recessive at another
loci.
A dog that is Heterozygous
means that the genes at a specific Loci have two different alleles.
For example the genes (Dd). When bred to another dog that is Heterozygous
(Dd) you will not only get black pups but also blue puppies. What happens
is that the (D) gene from one parent and the (D) gene from the other parent
will come together and produce (DD) black puppies. But also, the (d) gene
from one parent and the (d) gene from the other parent will come together
and this combination produces a Blue (dd) puppy. The last combination that
can be produced is (Dd). A Black pup will be born because (D) is dominant
to (d).
You won't necessarily
be able to tell a dogs genotype unless you have bred the dog many times
to females that carry the same recessive colors. Or unless you know what
genes the dogs carry from tracing the history for many generations back.
In the case of phenotype, you will be able to visibly see some of the genes
that they carry but recessives will be hidden because they aren't carried
in double dose or another allele is masking or hiding them.
When breeding recessive
colors you are not guaranteed to produce offspring of a given recessive
color. There is a certain percentage of pups that will be produced but
that percentage is based on 16 pups being born. This percentage is based
on the principle of Mendilian Law. To insure
that you produce the recessive color, 16 would have to be born. The
average litter is generally far less than 16 pups and would explain why
the recessive color is not showing up. For example, if you breed two black
and white dogs together that both carry chocolate as a recessive, you may
or may not get the chocolate colored puppies because the specific genes
did not combine in this particular mating. If you breed these same dogs
again, you may get chocolate pups this time because the recessive genes
came together.
How do I know if my dog carries a recessive
color gene?
.
The only absolute way of determining
if your dog carries a recessive is to know the color of your dogs parents.
If your dogs parents are visibly showing a recessive color then
they will pass one of these genes to their offspring. It should be noted
that the parents themselves can be different recessive colors (example:
one parent chocolate and the other parent blue) in this case each offspring
will inherit two recessive genes.
There is also another factor to
take into consideration when determining recessive colors and that is the
colors of the grandparents or as far back as you can go. If any of the
dogs in the heritage are a recessive color then their is a possibility
that your dog will have been passed this gene. Anytime a dog of a recessive
color is bred to a dog that is not, there is a 50% chance that the offspring
will get this recessive gene but will not be a recessive color visibly.
If you suspect that
your dog has a recessive color this may be determined by test breeding.
If your dogs have produced offspring that is a different color than both
the parents you will know for sure that your dogs carry a particular color
recessively.
.
It will be advantageous
at this point to know the difference between a recessive gene and
an epistatic/hypostatic gene. Although they act similar in that a double
dose needs to be present in order to visibly show, their order of dominance
is established within their given Loci. For example the color Tan (ay)
is hypostatic to the color black (A) and when bred together they will produce
all black puppies. The (ay) Tan will be dominated in this instance and
become Hypostatic to black because it is within the same Loci. If this
same dog that has the formula (A) black and (ay) Tan also carried a single
chocolate (b) gene, then this (b) chocolate gene would be a recessive gene
because when combined with the alleles at a different Loci it is
dominated.
.
Recessives cannot be
visibly seen unless the dog carries it in double dose. Both parents must
carry a compatible recessive in order for any additional colors to be produced.
Or one parent must be a recessive color and bred to a dog that carries
that specific recessive gene. If both dogs are carrying a recessive gene,
not all of their offspring will be the particular recessive color. If both
your dogs to be bred are the same recessive color they will
only produce that recessive color unless they are carrying another recessive
gene.
.
All of the following recessive colors
can hide under your dogs coat color.
The colors produced by (dd) - Blue, Charcoal, Tan
Apricot
The colors produced by (ee) - Clear Red, Lemon,
Apricot, Wheaten
The colors produced by (bb) - Chocolate, Chocolate
Apricot, Chocolate Tan,
The colors produced by (cchcch) - Silver Fawn,
White
It should be noted that combinations of recessive
genes and recessives combined with dominant genes at specific Loci will
produce additional colors. These colors being Apricot, Blue Fawn,
Weimaraner Gray, Pearl, Silver, Chocolate Silver and Creme. All formulas
are shown on the pages explaining each individual color.
The most Dominant gene at a specific Loci are
shown in capital letters within a formula. See Dogs
Genetic Makeup. Recessive and Hypostatic/Epistatic understanding is
a complicated issue..
Agouti, Tan, Saddle Back and Black/Tan are Epistatic
or Hypostatic to one another and can hide under the coat color of a black
or a white dog. Sable is commonly confused with Tan but Sable is very different
in genetic formula from Tan even though they may look the same. Sable is
actually a combination of Tan and Black and Tan. Black and Tan is
sometimes considered a recessive because when you breed Sable to a Black
and Tan dog, you will get some Black and Tan puppies and Sable puppies
but it is actually a Hypostatic color.
Here are some thoughts to ponder when trying
to determine your dogs recessive colors. Some of the recessive colors can
be a bit tricky.
1. A Silver dog is not only a dilute color but
also carries the graying gene in double dose.
2. Any color dog can carry the Lemon or Clear
Red gene recessively.
3. A Chocolate dog can carry a Blue gene recessively.
4. A Blue dog can carry a Chocolate gene recessively.
5. Clear Red is actually a black dog that has
a (e) gene that restricts black pigment from forming changing the coat
color to a very Clear Red color. It is the same formula as Lemon and varies
in color and tone due to modifying genes.
6. A Sable dog bred to a Black/Tan dog will produce
Sable and also Black/Tan offspring.
7. A Sable dog bred to a Sable dog will produce
Sable and Black/Tan offspring.
8. Any color can exist under the coat color of
a White dog.
9. Black color can hide ALL genes recessively
with the exception of Merle (M) and the Graying Gene (G).
10. The color Weimaraner Gray or Pearl is chocolate
and blue in double dose.
11. A Blue Fawn dog is actually a Sable dog with
a double dose of blue.
12. Kerry Blue, Mustard, Pepper and Yorkie Blue
are the same formula with an allele changed at the (A Series Loci). |
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