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I have had in mind for some time to write about color genetics. Now it might be
the time. First, about my thoughts about the "agouti" color, because
it has popped up several times. I know that color genetics research spesific to
Siberian Huskies has not officially been done, but I think that most
owners/breeders have made their own hypothesis about color heredity even if
they have never read more than "black is dominant to copper"
I myself have had Siberians for over 15 years, but my history of amateur color
research goes much further. This text is about how I understand color and color
genetics. I have included a list of books at the end, that I have read - some
of them many times, in search of more knowledge about this "colorful"
branch of science. Of course you can learn nothing if you don´t know anything
about genetics, heredity, chromosomes, loci, genotype, phenotype, etc., so I
hope my article is not incomprehensible to beginners. I have also included some
notes and statements that I have copied for myself from these various books,
and I apologize that I cannot always remember anymore from which book each
statement came. These quotes are separated, with or without the author´s name.
From old black and white photographs, you can find that early imports and
foundation Siberian dogs often were "solid" colored. That is, they
had a minimum amount of white in their coats. The black and white photos can be
misleading, because all dark dogs seem to be BLACK. Of course, it could be that
these dogs, in living color, could have been brown(ish), grey(ish), wolf
(colored), or agouti, but definitely "solid dark" on their faces as
well as their bodies. That is why I do not agree with the widely spread
statement: "It is understood that the Siberian Husky retains white
underportions and masks".
As it states in the standard; "The Siberian Husky can be of any color,
from black to pure white and a variety of markings on the head is common".
To my knowledge, white spotting is or is not present to a spesific genetic
process and it has nothing to do with the general coat color, be it red, black
or agouti. A dog that is genetically agouti can as well have irish markings, if
his genetic makeup so defines.
I have used the following symbols for the Agouti Series in my text:
A
s
- dominant black/red depending on other color genes;
a
y
- sable/tan;
a
w
- agouti/wild color;
a
s
- saddle markings;
a
t
- tanpoint;
a
- recessive black.
FACTS ABOUT AGOUTI SERIES AND AGOUTI ALLELE
"Most wolves have a protectively coloured grey coat, in which black and
yellow pigments are intermingled on the same hair
somewhat as in the agouti pattern of rodents.
This pattern is wanting in most dogs, but has been retained in some examples
of Eskimo-dogs or "husky". It is probably due to a dominant
factor." (author?)
"Wolf -
Canis Lupus
, genetically this species is normally black agouti, but it is stated that
almost red forms were sometimes caught, possibly homotzygous for
a
y
(sable/tan) moreover it is reported that hybrids between dog and wolf may have
black, black and tan or "uniform ochreous" coat color so that various
agouti alleles
From these statements we can clearly find out that scientifically and
genetically, when speaking of agouti color, we actually speak of a
color pattern where black and yellow pigments are intermingled on the same
individual hair.
It has nothing else to do with the color of the agouti rodent, other than the
term and the banding of the individual hair.
The explanation of the effects of the agouti allele to the PHENOTYPE is as
follows:
"Agouti color; majority of the hairs have black tips, then yellow or
whitish band below after which there may be another dark band although often
the color gets coninuously paler toward the skin. All these coat colors
(referring to those colors controlled by the agouti series, IKa)
tend to be lighter on the extremities and underside of the dog than on the
back; they are all darker at birth than when adult." (C.C.Little ?)
"Yellow bands on agouti marked hairs vary in color from rich red to palest
straw-color and this is true also of the tan markings on a bi-colored (
a
t
) and saddle marked (
a
s
) dogs." (Iljin)
"Below
a
y
(sable/tan) is
a
w
(agouti/wild) which allows almost complete dark pigmentation at birth. This
pigment is progressively lost as the individual grows older. In the adult an
agouti-like coat of banded hairs is found." (Burns)
Noted scientists like Little, Burns&Fraser and Robinson have adopted the
hypothesis that the agouti or wild color allele belongs to the agouti series,
genes which control the amount of black and yellow in the hair and coat. Some
geneticists, on the other hand, have made the the same presumption as written
before: It is probably due to a dominant factor. If that were so, it would
propose a new locus for that gene.
ABOUT PHENOTYPICAL AGOUTI COLOR IN THE SIBERIAN HUSKY
Partial agouti is said to be more common and that is where white spotting and
dilution come into the picture. If one wishes to find a "real, genuine
agouti
colored" Siberian, there are many more color genes to think of than ONLY
the agouti allele, be it an individual dominant factor or an allele in the
agouti series.
The dog has to be homozygous in the following loci of the color genome: no
white spotting
(SS)
; full extension
(EE)
; agouti
(a
w
a
w
,
if independent factor
V
, then
V- + a
t
a
t
)
; black
(BB)
; full color
(CC)
; no greying
(GG)
; no dilution
(DD)
; no paling
(PP)
. To get this rare color type, one has to do a lot of color breeding, which
obviously would ruin our breed.
The more common colors, like wolf grey or silver grey, where the yellow band on
an individual hair has paled to buff or nearly white, are GENETICALLY agouti
too - even if the dilution genes give it a little different appearance. One
must remember that genetic research has been done mainly in regard to the guard
hairs - the undercoat has been nearly forgotten! It is believed that the effect
of the color genes is directed separately to the guard hairs and to the
undercoat. That is why two dogs with identical genes affecting their guard
hairs appear different if their undercoat is of different color. Two breeds of
different coat texture, that have identical color genes, give a different
optical illusion - for example: a salt´n´pepper Schnauzer versus a
silver grey
Siberian.
The Siberian Husky is also under the same color genetic laws and rules as other
breeds, so it is easy to learn about Siberian color by reading about color
genetics in general.
After all this chat about the agouti color, I hope that the reader can make the
separation between PHENOTYPICAL agouti color and GENOTYPICAL agouti alleles and
I also hope that I haven´t bored you with all this genetics stuff.
References:
The scientific term for wild coloring is "agouti". The color term is
a loan from the name of the South American rodent Agouti, and is defined as:
Meaning a coat color type that has stripes or banding on an individual hair.
As our breed has often a coat color resembling that of the wolf, it is
necessary provide several paragraphs explaining the genetic makeup of the wolf
coat color:
If we accept the description of phenotypical agouti color as it is presented in
Rice´s article (appearing in the 2
nd
and 3
rd
Editions of
The International Siberian Husky Club presents the Siberian Hysky
), we find that it is a color pattern, where all color is deep and dark, with
no dilution factors present.