White pants? Ooops, I mean white jeans. Eh, make that albino genes. As
far as I know, no one has worked out the genetics of albinism in ferrets
(except in a basic manner), but I would expect it to follow the basic rules
and conditions of albinism in other mammals, BTW, all vertebrate groups can
and do exhibit albinism from time to time. It is a common mutation.
Essentially albinism is caused by a mutation that prevents the formation of
pigmentation. The external appearance (phenotype) can be the result of
several different mutations within the chromosomes (geneotype). Albinism
can be caused by a mutation that prevents the body from manufacturing the
pigments, a mutation that prevents the body from recognizing the proteins
that key for the pigments, or even the body's inability to make the proteins
that tell the body to make pigments. Three different reasons (from a
possibly infinite number), but all look the same. However, in most cases of
mammalian albinism, the reason is a mutated gene that prevents the
manufacture of pigments.
In the vast majority of cases, albinism is a recessive trait; that is, it
cannot express itself without having two copies present. Albino does not
"blend," that is, having a single gene for albinism does not make you
lighter or different colored. You either are an albino, or you are not.
That simple. Also, the trait can be carried for many generations without
expression, then link up with another albinist gene, resulting in albino
offspring and a shocked breeder.
Other factors beside albinism can result in light-colored coats. Usually
this is the result of a protein that blocks the formation of pigments, such
as the seasonal "albinism" of northern mammals, like in the weasel, hare and
fox. This is not true albinism, because the pigments still exist in the
skin and eyes, and some of the fur, and they return with the next moult.
Other times, animals can have a white or light colored coat, such as in the
Black-eyed whites, and this trait can blend with other coat colors to form
intermediates of some type. Again, these are not albinos, and the lack of
pigment in the fur reflects changes in the genetics at a different location
than for albinism. In fact, albinos can have the same genes as your typical
sable, and would look like one if they could make the pigments. BTW, the
eyes are red because you can see the red blood vessels on the retina (very
vascular). The eyes of dead albinos turn white or light bluish.
As I've already said, I am not sure of the exact genetics of ferret
coloration, but I would expect fur coloration to be carried in 3 or more
places. It would require a minumum of three different locations to explain
the existing main colorations; sable, panda, and cinnamon. Some breeders
will surely object to this simplification, but from what I've seen and read,
all other "breeds" are in fact either variations or combinations of these
three, excluding the albinos of course. Personally, I think fur coloration
may turn out to be carried on even more than three locations, perhaps as
many as five, but the extra locations are either close to one or more of the
other locations so become linked to nearby traits. Which is why some
colorations exhibit a high incidence of deafness or lowered mental
abilities. (In humans, we see similar effects in blonds. Oooooo, a blond
joke!) Occasionally, because of cross-overs or whatever, they throw off
expectations and you get a different look than expected. (OK, I admit I did
some nasty math to get to the figure of three locations. I would tell you
how I did it, but then I would have to kill you...)
Historically, I think the tendency was for albinos to be called ferrets, and
sables, easily just as domesticated, to be called either fitch,
fitch-polecat or polecat. Linneaus described an albino in setting up the
ferret binomial, but I think he understood ferrets existed in many
coloration schemes, and used the albino as a type species because he could
be sure the breed was pure. They may not have had a clue about genetics in
the 18th century, but they fully understood husbandry, and knew to keep
albinos white. Linneaus knew ferrets were sometimes back-crossed with wild
polecats to improve the hunting instincts, and wanted his type specimen to
be a true representation of the ferret. Not long after Linneaus described
the ferret, it was described in a British paper as having two coloration
schemes, the red-eyed white, and the fitch, which was lighter and less
masked than the polecat, a coloration scheme the still generally holds.
Without a doubt, the ancestral coloration of the ferret was sable. No
doubt, no argument. In fact, sable, or a very close variation, is ancestral
to ALL members of the weasel subgroup, including mink, weasels, polecats,
and ferrets, as well as most of the Mustelidae. During the domestication
process and undoubtedly due to inbreeding, albinism developed, and was
obviously selected for, perpetuating the trait. I cannot answer the
question. "why did they want albinos?" because I wasn't there, there is a
curious lack of archaeological evidence, and because the people who did it
are long dead and they didn't write down their reasons. They just seemed to
like albino ferrets, and you can speculate as to why, but any speculation is
100% pure storytelling.
What would be very nice is for breeders to publish their "formulas" for
obtaining certain colorations and breeds. With that type of data it would
be fairly simple to determine the relationships between the various
locations that control for coloration. Links, blending, dominance and other
characteristics could be worked out for the ferts, and then breeders could
make predictions and exploit the data for even more variations.
My apologies if in simplification or condensation the genetics or breeding
portions of this post are unclear. I will be happy to write much much more
and send it privately. I also apologize for typos. For some reason, my
server is randomly adding or deleting the occasional character.
Pigmentally Challenged Bob C,12 Fitch of Color and 5 White Girls
[Posted in FML issue 1917]
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