|
 As
we have already seen, our cat can be basically black, blue, chocolate lilac,
cinnamon or fawn (indeed red or cream but will test these colours later) but
will be tabby or not ?
Two genes
are responsible for the
presence or not of light hairs crossed with dark (called
"agoutis").
ü
"A+" :
presence of agouti hairs (this cat is tabby)
ü
"a" : all
the hairs are dark.
In fact there are really self hairs (those which make the tabby pattern) and
others dark, crossed with darker colour which gives the look of a self
(coloured) cat but it allows the persistence of a "ghost" we can see in some
cases like childhood, exposure to a strong sun or revealed by the silver gene or
the red.
A
real tabby cat has, at least, one tabby parent and almost always has some white
above the shops and on the chin. A cat with a red chin and some red around the
nose is self even if he’s got a strong ghost. A tabby looks clearer than a self
and often has the periphery of the ear white. The colour does not enter the ear.
There
are three
possible associations of these two
genes :
ü
"A+A+"
®
tabby homozygote, there will be only tabbies
ü
"A+a"
®
tabby heterozygote, if the cat is married with a self he may be able to give a
self kitten out of two, with a heterozygous like him, one out of four.
ü
"aa"
®
non tabby (or self) he can have only non tabbies with a non tabby, and allows to
bring to the form the heterozygotie of a tabby which is.
We now know whether our
kitten will be tabby or
not but which tabby ?
 The
"T" set of the tabby has three alleles classified in decreasing order of
dominance and which are going to show the amount of self hairs in comparison
with the back of the coat.
ü
"Ta" : ticked, almost all hairs are agouti, only a stripe of self
hairs on the back (it’s the typical coat of Abyssian).
ü
"T+" : mackerel or tabby also give the spotted, because of the
modifying genes, there are as many agouti hairs as self hairs.
ü
"tb" : tabby blotched, the self hair patterns, making big
drawings on his sides, take more space than agouti hairs.
These genes combine in
six different ways :
ü
"TaTa"
®
pure ticked (homozygote) he will have ticked kittens only with any partner.
ü
"TaT+"
®
ticked tabby, he can have tabby (or spotted) kittens if his pattern allows it.
ü
"Tatb"
®
ticked, carrying blotched, can have blotched kittens with a partner carrying
tabby, or tabby or spotted, with partner carrying "T+".
ü
"T+T+"
®
pure tabby or spotted, can give the only gene to his descendants.
ü
"T+tb"
®
tabby carrying blotched, can give blotched kittens with the right partner.
ü
"tb+tb"
®
blotched, strictly obliged to be homozygote, will give only "tb" to his
descendants.
There
is a
gene
which modifies the tabby look.
This gene “Wb” makes the pattern determined by “T” disappear. Gradually the
colouring pigment (black, blue,
red
and so on) is pushed away to the tip
of
the hairs and the ticking
becomes
a more or less long tipping, following the polygene and gives
the
Chinchilla,
Silver Shaded
or
Cameo
as
well as the Golden Shell or Shaded we find principally in the Persian, British
and sometimes Oriental breeds. "wb+" has no effect and leaves “T” express itself
normally.
Example
n°1 :
A
breeder marries his Oriental brown mackerel tabby male to a
black
female. There are three kittens,
a black and two brown blotched tabby kittens. What can we conclude ?
Answer :
A tabby cat is
"A+ T+" genetically, but we know he’s had a black kitten so he’s carrying "a"
and blotched, so, he’s carrying “tb”. His genotype is completed : “A+a
T+tb”. The black female allowed him to express the non tabby and she likely
hides a blotched which let the male express this hidden gene.
Example
n°2 :
A
British
Chinchilla female married to a male like
her, gives six kittens, among them four Chinchillas and two tabbies. What’s her
genotype ? And what can we say about the two partners ?
Answer :
The female is
“Wb” as she’s Chinchilla, but she carries the non Chinchilla “wb+” since she’s
had non Chinchilla kittens. The male has the same genotype, «Wb wb+» otherwise
the marriage couldn’t have given any tabbies kitten.
We’re
at the end of the tabbies, there is so many things to look upon.
Good
luck !
Traduction
de
Michèle
PASSEMARD (F)
|
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