1709 lines
92 KiB
Plaintext
1709 lines
92 KiB
Plaintext
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
FELINE GENETICS
|
|||
|
|
|
|||
|
|
R. Roger Breton
|
|||
|
|
Nancy J Creek
|
|||
|
|
|
|||
|
|
------------------------------
|
|||
|
|
|
|||
|
|
Cells, Chromosomes, and Genes
|
|||
|
|
|
|||
|
|
From a 35-pound Main Coon to a 5-pound Devon Rex; from the small
|
|||
|
|
folded caps of a Scottish Fold to the great, delicate ears of a Bali-
|
|||
|
|
nese; from the 4-inch coat of a Chinchilla Persian to the fuzzy down
|
|||
|
|
of a Sphinx; from the deep Ebony of a Bombay to the translucent white
|
|||
|
|
of a Turkish Angora; from the solid color of a Havana Brown to the
|
|||
|
|
rich tabbiness of a Norwegian Forest Cat: the variety and beauty to
|
|||
|
|
be found in the domestic cat is beyond measure. When these character-
|
|||
|
|
istics are coupled with the genetically-patterned and environmentally-
|
|||
|
|
tailored personalities of the individuals, it can be seen that each
|
|||
|
|
animal is as unique as it is possible to be. There truly is a cat for
|
|||
|
|
everyone.
|
|||
|
|
|
|||
|
|
Wide as the range of cats is, it pales when compared with the varie-
|
|||
|
|
ties of Other Pet. Why should the dog exhibit such a wide spectrum of
|
|||
|
|
body types, looking like completely different creatures in some cases,
|
|||
|
|
while cats always look like cats (as horses always look like horses)?
|
|||
|
|
The secrets behind the wide variations in possible cats, and why cats,
|
|||
|
|
unlike dogs, resist gross changes and always look like cats, can be
|
|||
|
|
found in its genetic makeup.
|
|||
|
|
|
|||
|
|
In order to understand what happens genetically when two cats do their
|
|||
|
|
thing, it is necessary to understand a few basic things about genetics
|
|||
|
|
in general. To study genetics, is to study evolution in miniature,
|
|||
|
|
for it is through the mechanism of genetics that evolution makes
|
|||
|
|
itself felt. In chapter 1, we showed how the gross evolution of the
|
|||
|
|
cat came about, and how this gross mechanism was applied to the Euro-
|
|||
|
|
pean Wildcat to evolve the African Wildcat, the immediate forerunner
|
|||
|
|
of our cats. We will examine this mechanism itself to better under-
|
|||
|
|
stand how the first domestic cat has become the dozens of breeds
|
|||
|
|
available today, and how cat breeders use this mechanism to create new
|
|||
|
|
breeds or improve existing ones.
|
|||
|
|
|
|||
|
|
Cats, like people, are multi-cellular creatures: that is, their
|
|||
|
|
bodies are composed of cells, lots and lots of cells. Unlike primi-
|
|||
|
|
tive multicellular creatures, cat bodies are not mere colonies of
|
|||
|
|
cells, but rather societies of cells, with each type of cell doing a
|
|||
|
|
specific task. To one specific type of cells, the germ cells (ova in
|
|||
|
|
females and sperm in males), fall the task of passing the genetic code
|
|||
|
|
to the next generation. The method the Great Engineer has developed
|
|||
|
|
to carry this out is one of the most awesome, most elegant, and most
|
|||
|
|
beautiful processes in nature.
|
|||
|
|
|
|||
|
|
The cells of a cat, with few special exceptions, are eukaryotic, that
|
|||
|
|
is, they have a membrane surrounding them (acting as a sort of skin),
|
|||
|
|
are composed of cytoplasm (cell stuff) containing specialized orga-
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 1
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
nelles (the parts that do the cell's task), and have an inner membrane
|
|||
|
|
surrounding a nucleus. It is this nucleus that contains all the
|
|||
|
|
genetic materials.
|
|||
|
|
|
|||
|
|
Within the nucleus of a cell are found the chromosomes, long irregular
|
|||
|
|
threads of genetic material. These chromosomes are arranged in pairs:
|
|||
|
|
19 pairs in a cat, 23 pairs in a human. It is these 38 chromosomes
|
|||
|
|
that contain the "blueprint" for the individual cat.
|
|||
|
|
|
|||
|
|
When inspected under a microscope, the chromosomes reveal irregular
|
|||
|
|
light and dark bands: hundreds of thousands, perhaps millions per
|
|||
|
|
chromosome. These light and dark bands are the genes, the actual
|
|||
|
|
genetic codes. Each gene controls a single feature or group of fea-
|
|||
|
|
tures in the makeup of the individual. Many genes interact: a single
|
|||
|
|
feature may be controlled by one, two, or a dozen genes. This makes
|
|||
|
|
the mapping of the genes difficult, and only a few major genes have
|
|||
|
|
been mapped out for the cat.
|
|||
|
|
|
|||
|
|
The chromosome is itself composed primarily of the macromolecule DNA,
|
|||
|
|
(deoxyribonucleic acid): one single molecule running the entire
|
|||
|
|
length of the chromosome. DNA is a double helix, like two springs
|
|||
|
|
wound within each other. Each helix is composed of a long chain of
|
|||
|
|
alternating phosphate and deoxyribose units, connected helix to helix
|
|||
|
|
by ladder-like rungs of four differing purine and pyridamine com-
|
|||
|
|
pounds.
|
|||
|
|
|
|||
|
|
It is not the number of differing compounds that provide the secret of
|
|||
|
|
DNA's success, but rather the number of rungs in the ladder (uncounted
|
|||
|
|
millions) and the order of the amino acids that make up the rungs.
|
|||
|
|
The four different amino acids are arranged in groups of three, form-
|
|||
|
|
ing a 64-letter alphabet. This alphabet is used to compose words of
|
|||
|
|
varying length, each of which is a gene (one particular letter is
|
|||
|
|
always used to indicate the start of a gene). Each gene controls the
|
|||
|
|
development of a specific characteristic of the lifeform. There is an
|
|||
|
|
all-but-infinite number of possible genes. As a result, the DNA of a
|
|||
|
|
lifeform contains its blueprint, no two alike, and the variety and
|
|||
|
|
numbers of possible lifeforms has even today barely begun.
|
|||
|
|
|
|||
|
|
Mitosis and Mendel
|
|||
|
|
|
|||
|
|
When a cell has absorbed enough of the various amino acids and other
|
|||
|
|
compounds necessary, it makes another cell by dividing. This process
|
|||
|
|
is called mitosis, and is fundamental to life.
|
|||
|
|
|
|||
|
|
Not too long ago, it was thought that the chromosomes were generated
|
|||
|
|
immediately prior to mitosis, and dissolved away afterwards. This
|
|||
|
|
turned out not to be true. The extremely tiny chromosomes, normally
|
|||
|
|
invisible in an optical microscope, shorten and thicken during mito-
|
|||
|
|
sis, becoming visible temporarily.
|
|||
|
|
|
|||
|
|
The rather complex process of mitosis can perhaps be explained simply
|
|||
|
|
as a step-by-step process:
|
|||
|
|
|
|||
|
|
Mitosis begins when the cell senses sufficient growth and nutrients to
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 2
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
support two cells.
|
|||
|
|
|
|||
|
|
The invisible chromosomes duplicate themselves through the wonder of
|
|||
|
|
DNA replication. Various enzymes are used as keys to unlock and
|
|||
|
|
unwind the double helix into two single helices. Each of these he-
|
|||
|
|
lices then uses other enzymes to lock the proper parts (the amino
|
|||
|
|
acids and other stuff) together to build a new second helix, complete
|
|||
|
|
with all transverse rungs, so that the results will be exact replicas
|
|||
|
|
of the original double helix. This winding and unwinding of the DNA
|
|||
|
|
can take place at speeds up to 1800 rpm! The two daughter chromosomes
|
|||
|
|
remain joined at a single point, called the centromere.
|
|||
|
|
|
|||
|
|
The cromosomes then wind themselves up, shortening and thickening,
|
|||
|
|
making them visible under the microscope, and attach themselves to the
|
|||
|
|
nuclear membrane.
|
|||
|
|
|
|||
|
|
The nuclear membrane then dissolves into a fibrous spindle, with at
|
|||
|
|
least one fiber passing through each centromere (there are many more
|
|||
|
|
fibers than centromeres).
|
|||
|
|
|
|||
|
|
The fibers then stretch and pull the centromeres apart, pulling the
|
|||
|
|
chromosomes to opposite sides of the cell.
|
|||
|
|
|
|||
|
|
The spindles dissolve into two new nuclear membranes, one around each
|
|||
|
|
group of chromosomes.
|
|||
|
|
|
|||
|
|
The chromosomes unwind back into invisibility, the cell divides, and
|
|||
|
|
mitosis is complete. Genetically, each daughter cell is an exact
|
|||
|
|
duplicate of the parent cell.
|
|||
|
|
|
|||
|
|
Since the genetic coding is carried in the rungs of the DNA and only
|
|||
|
|
consists of four different materials arranged in groups of three to
|
|||
|
|
form words of varying length written with a 64-letter alphabet, the
|
|||
|
|
instructions for a "cat" may be considered to consist of two sets of
|
|||
|
|
19 "books," each millions of words long, one set from each of the
|
|||
|
|
cat's parents. The numbers of possible instructions are more than
|
|||
|
|
astronomical: there are far more possible instructions in one single
|
|||
|
|
chromosome than there are atoms in the known universe!
|
|||
|
|
|
|||
|
|
A single gene is a group of instructions of some indeterminate length.
|
|||
|
|
Somewhere among all the other codes is a set of instructions composing
|
|||
|
|
the "white" gene, and what that set says will determine if the cat is
|
|||
|
|
white or non-white.
|
|||
|
|
|
|||
|
|
Since a cat receives two sets of instructions, one from each parent,
|
|||
|
|
what happens when one parent says "make the fur white" and the other
|
|||
|
|
says "make the fur non-white"? Will they effect a compromise and make
|
|||
|
|
the fur pastel? No, they will not. Each and every single gene has at
|
|||
|
|
least two levels of expression (many have more), called alleles, which
|
|||
|
|
will determine the overall effect. In the case given, the "make the
|
|||
|
|
fur white" allele, "W", is dominant, while the "make the fur non-
|
|||
|
|
white" allele, "w", is recessive. As a result, the fur may be white
|
|||
|
|
or non-white, not pastel (we're only speaking of the "white" gene
|
|||
|
|
here, a gray cat is caused by an entirely different gene).
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 3
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
In order to understand how this works, lets run through a couple of
|
|||
|
|
simple examples using the white gene. A cat has two and only two
|
|||
|
|
white genes. Since each white gene, for the purposes of our examples,
|
|||
|
|
consists of one of two alleles, "W" or "w", a cat may have one of four
|
|||
|
|
possible karyotypes (genetic codes) for white: "WW", "Ww", "wW",
|
|||
|
|
"ww". Since "W" is dominant to "w", the codes "WW", "Ww", and "wW"
|
|||
|
|
produce white cats, while the code "ww" produces a non-white cat.
|
|||
|
|
|
|||
|
|
| W w
|
|||
|
|
--+--------
|
|||
|
|
W | WW Ww
|
|||
|
|
w | wW ww
|
|||
|
|
|
|||
|
|
The double-dominant "WW" white cat has only white alleles in its white
|
|||
|
|
genes. It is classed as homozygous (same-celled) for white, and will
|
|||
|
|
produce only white offspring, regardless of the karyotype of its mate.
|
|||
|
|
|
|||
|
|
The single-dominant "Ww" or "wW" white cat has one of each allele in
|
|||
|
|
its white genes. It is classed as heterozygous (different-celled) for
|
|||
|
|
white, and may or may not produce white offspring, depending upon the
|
|||
|
|
karyotype of its mate.
|
|||
|
|
|
|||
|
|
The recessive "ww" non-white cat has only non-white alleles in its
|
|||
|
|
white genes. It is classed as homozygous for non-white, and may or
|
|||
|
|
may not produce white offspring, depending upon the karyotype of its
|
|||
|
|
mate.
|
|||
|
|
|
|||
|
|
Assuming these cats mate, there are sixteen different possible karyo-
|
|||
|
|
type combinations. Since each cat in these sixteen combinations will
|
|||
|
|
pass on to their offspring one and only one allele, there are four
|
|||
|
|
possible genetic combinations from each mating. There are sixty-four
|
|||
|
|
possible combinations of offspring.
|
|||
|
|
|
|||
|
|
| WW | Ww | wW | ww
|
|||
|
|
| W W | W w | w W | w w
|
|||
|
|
------+--------+--------+--------+--------
|
|||
|
|
WW W | WW WW | WW Ww | Ww WW | Ww Ww
|
|||
|
|
W | WW WW | WW Ww | Ww WW | Ww Ww
|
|||
|
|
------+--------+--------+--------+--------
|
|||
|
|
Ww W | WW WW | WW Ww | Ww WW | Ww Ww
|
|||
|
|
w | wW wW | wW ww | ww wW | ww ww
|
|||
|
|
------+--------+--------+--------+--------
|
|||
|
|
wW w | wW wW | wW ww | ww wW | ww ww
|
|||
|
|
W | WW WW | WW Ww | Ww WW | Ww Ww
|
|||
|
|
------+--------+--------+--------+--------
|
|||
|
|
ww w | wW wW | wW ww | ww wW | ww ww
|
|||
|
|
w | wW wW | wW ww | ww wW | ww ww
|
|||
|
|
|
|||
|
|
Inspecting these possible offspring, several patterns emerge. Of the
|
|||
|
|
64 possible offspring, 16, or exactly one-quarter, have any given
|
|||
|
|
pattern. This means that one quarter of all possible matings will be
|
|||
|
|
homozygous for white, "WW", two quarters will be heterozygous for
|
|||
|
|
white, "Ww" or "wW" (which are really the same thing), and one quarter
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 4
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
will be homozygous for non-white, "ww". Since homozygous white and
|
|||
|
|
heterozygous white will both produce white cats, three-quarters of all
|
|||
|
|
possible combinations will produce white cats, and only one-quarter
|
|||
|
|
will produce non-white cats. This 3:1 ratio is known as the Mendelian
|
|||
|
|
ratio, after Gregor Johann Mendel, the father of the science of genet-
|
|||
|
|
ics.
|
|||
|
|
|
|||
|
|
|
|||
|
|
Further inspection leads us to several conclusions. If a homozygous
|
|||
|
|
white cat mates, all offspring will be white. If two homozygous white
|
|||
|
|
cats mate, all offspring will be homozygous white. If a homozygous
|
|||
|
|
white cat mates with a heterozygous white cat, there will be both
|
|||
|
|
homozygous white and heterozygous white offspring in a 1:1 ratio. If
|
|||
|
|
a homozygous white cat mates with a homozygous non-white cat, all
|
|||
|
|
offspring will be heterozygous white. Thus, a homozygous white cat
|
|||
|
|
can only produce white offspring, regardless of the karyotype of its
|
|||
|
|
mate, and is said to be true breeding for white.
|
|||
|
|
|
|||
|
|
If two heterozygous white cats mate, there will be homozygous white,
|
|||
|
|
heterozygous white, and homozygous non-white offspring in a ratio of
|
|||
|
|
1:2:1. The ratio of white to non-white offspring is the Mendelian
|
|||
|
|
ration of 3:1. If a heterozygous white cat mates with a homozygous
|
|||
|
|
non-white cat, there will be both heterozygous white and homozygous
|
|||
|
|
non-white offspring in a 1:1 ratio.
|
|||
|
|
|
|||
|
|
If two homozygous non-white cats mate, all offspring will be homozy-
|
|||
|
|
gous non-white. Homozygous non-white cats are therefore true-breeding
|
|||
|
|
for non-white when co-bred.
|
|||
|
|
|
|||
|
|
Geneticists differentiate between what a cat is genetically versus
|
|||
|
|
what it looks like by defining its genotype versus its phenotype. A
|
|||
|
|
homozygous white cat has a white genotype and a white phenotype.
|
|||
|
|
Likewise, a homozygous non-white cat has a non-white genotype and a
|
|||
|
|
non-white phenotype. A heterozygous white cat, on the other hand, has
|
|||
|
|
both a white genotype and a non-white genotype, but only a white
|
|||
|
|
phenotype.
|
|||
|
|
|
|||
|
|
Naturally, in a given litter of four kittens the chances of having a
|
|||
|
|
true Mendelian ratio are slim (slightly better than 1:11), so several
|
|||
|
|
generations of pure white kittens could be bred, still carrying a
|
|||
|
|
recessive non-white allele. In all good faith you then breed your
|
|||
|
|
several-generations-all-white-but-heterozygous female to a similar
|
|||
|
|
several-generation-all-white-but heterozygous male and voila! A black
|
|||
|
|
kitten! The non-white genotype has finally shown itself.
|
|||
|
|
|
|||
|
|
This Mendelian patterning is the basic rule of genetics. Since the
|
|||
|
|
rule is so simple, why is it so hard to predict things genetically?
|
|||
|
|
The reason is that we are dealing with more than one gene from each
|
|||
|
|
parent. The number of possible offspring combinations is two to the
|
|||
|
|
power of the number of genes: one gene from each parent is two genes,
|
|||
|
|
two squared is four possibilities; two from each parent is four, two
|
|||
|
|
to the fourth is sixteen; three from each is six, two to the sixth is
|
|||
|
|
64;... There are literally hundreds of millions of genes for one cat,
|
|||
|
|
yet a mere hundred from each parent produces a 61-digit number for the
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 5
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
possible offspring combinations!
|
|||
|
|
|
|||
|
|
Meiosis
|
|||
|
|
|
|||
|
|
Since each cell contains the entire chromosome set, 19 pairs, how is
|
|||
|
|
it possible for a parent to pass on only the genes from one chromosome
|
|||
|
|
of a pair, and not both. This is accomplished via the gametes: the
|
|||
|
|
germ cells, ova for females and sperm for males. Within the gonads
|
|||
|
|
(ovaries or testes), these special cells go through a division process
|
|||
|
|
known as meiosis.
|
|||
|
|
|
|||
|
|
Unlike the normal process of mitosis, where the chromosomes are faith-
|
|||
|
|
fully replicated into duplicates of themselves, in meiosis the result-
|
|||
|
|
ant gametes have only half the number of chromosomes, one from each
|
|||
|
|
original pair. This involves a double division.
|
|||
|
|
|
|||
|
|
As in mitosis, meiosis begins when the cell senses sufficient growth
|
|||
|
|
and nutrients to support division. The invisible chromosomes are
|
|||
|
|
duplicated through DNA replication. As usual, the two daughter chro-
|
|||
|
|
mosomes remain joined at the centromere. The chromosomes wind them-
|
|||
|
|
selves up, shortening and thickening, becoming visible under the
|
|||
|
|
microscope. Each new chromosome twin aligns itself with its homolo-
|
|||
|
|
gous counterpart: the twin chromosome from its opposite number in the
|
|||
|
|
original chromosome pair. The two twin chromosomes intertwine into a
|
|||
|
|
tetrad and exchange genes in a not clearly understood process that
|
|||
|
|
randomizes the genes between the twins. The tetrad attaches itself to
|
|||
|
|
the nuclear membrane. The nuclear membrane dissolves into a spindle,
|
|||
|
|
with at least one fiber passing through both centromeres of each
|
|||
|
|
tetrad. The fibers stretch and pull the tetrads apart, pulling the
|
|||
|
|
chromosomes twins to opposite sides of the cell. Once the chromosome
|
|||
|
|
twins are at the poles of the spindle, the spindle dissolves and
|
|||
|
|
reforms as two separate parallel spindles at right angles to the
|
|||
|
|
original spindle, with at least one fiber through each centromere. At
|
|||
|
|
this time there are effectively two mitoses taking place. The paral-
|
|||
|
|
lel spindles pull the centromeres apart, forming four separate groups
|
|||
|
|
of chromosomes, each of which consists of one-half the normal number.
|
|||
|
|
The spindles dissolve and four new nuclear membranes form, one around
|
|||
|
|
each group of chromosomes. The chromosomes unwind back into invisi-
|
|||
|
|
bility, the cell divides into four gametes, each having 19 chromo-
|
|||
|
|
somes, and meiosis is complete.
|
|||
|
|
|
|||
|
|
At the moment of conception, a single sperm penetrates a single ovum,
|
|||
|
|
the ovum absorbs the sperm, merging the sperm's nucleus with its own
|
|||
|
|
and pairing the two sets of chromosomes. The ovum has now become a
|
|||
|
|
zygote, which begins dividing through the normal mitosis process, and
|
|||
|
|
a kitten is on its way.
|
|||
|
|
|
|||
|
|
Male, Female, and Maybe
|
|||
|
|
|
|||
|
|
The 19 pairs of chromosomes in a cat carry the numbers 1 through 18,
|
|||
|
|
plus "X" and "Y". The "X" and "Y" chromosomes are very special, for
|
|||
|
|
they determine the sex of the kitten. A female cat has two "X" chro-
|
|||
|
|
mosomes, "XX", while a male cat has one "X" and one "Y" chromosome,
|
|||
|
|
"XY", so if we follow the Mendelian pattern for sex determination we
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 6
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
find that the female parent can provide only an "X" chromosome to her
|
|||
|
|
offspring, while the male parent can provide either an "X" chromosome
|
|||
|
|
or a "Y" chromosome. The resulting kittens are either "XX" or "XY",
|
|||
|
|
as determined by the father. The same rule also applies to people
|
|||
|
|
(Sorry guys, if you and the wife have seven girls, it's your fault,
|
|||
|
|
not hers!).
|
|||
|
|
|
|||
|
|
Since the sex chromosomes follow the same rules as the other chromo-
|
|||
|
|
somes, why bother mentioning them separately? Because they don't
|
|||
|
|
exactly follow the same rules: the "X" chromosome is longer than the
|
|||
|
|
"Y" chromosome, and it is this extra length that carries the codes for
|
|||
|
|
the female. When there is only one set of these extra codes, they act
|
|||
|
|
as recessives, allowing the male characteristic to dominate. When
|
|||
|
|
there are two sets, they act as dominants, and suppress the male
|
|||
|
|
characteristics. Thus, female and male kittens.
|
|||
|
|
|
|||
|
|
We could end the argument here if it weren't for two complications.
|
|||
|
|
First, the extra-length of the "X" chromosome carries some genes that
|
|||
|
|
are for other than sex characteristics (such as the gene for orange
|
|||
|
|
fur): such characteristics are said to be sex-linked, and operate
|
|||
|
|
differently in males and females.
|
|||
|
|
|
|||
|
|
A further complication comes with incomplete separation of the "X"
|
|||
|
|
gene twin at the centromere. An "X-X" gene twin has its centromere
|
|||
|
|
exactly where "Y"'s would become "X"'s. If an "X" were to fracture at
|
|||
|
|
the centromere during the process of separation, it would become an
|
|||
|
|
effective "Y". This is rare but by no means unheard of, and produces
|
|||
|
|
a "false" "Y" (shown as "y" to differentiate it from a female "XX"
|
|||
|
|
parent.
|
|||
|
|
|
|||
|
|
Another variation is incomplete separation, where only a "false cen-
|
|||
|
|
tromere" is separated from the gene twin, with or without a part of
|
|||
|
|
the twin, causing one gamete to have 18 chromosomes (neither an "X" or
|
|||
|
|
a "y" while the other has 20 (either two "X"'s, an "Xy", or two "y"'s,
|
|||
|
|
depending on the point and angle of fracture).
|
|||
|
|
|
|||
|
|
These variations on the sex chromosomes mean that a female, being "XX"
|
|||
|
|
in nature, can produce ova with the following: "XX", "Xy", "yy", "X",
|
|||
|
|
"y", or "O" (no sex chromosome). A male, being "XY", can produce
|
|||
|
|
sperm with "XY", "Yy", "X", "Y", "y", or "O". A zygote, taking one
|
|||
|
|
gamete from each parent, may then be any of the following 36 possibil-
|
|||
|
|
ities:
|
|||
|
|
|
|||
|
|
| XX Xy yy X y O
|
|||
|
|
---+--------------------------------
|
|||
|
|
XY | XXXY XXYy XYyy XXY XYy XYO
|
|||
|
|
Yy | XXYy XYyy Yyyy XYy Yyy YyO
|
|||
|
|
X | XXX XXy Xyy XX Xy XO
|
|||
|
|
Y | XXY XYy Yyy XY Yy YO
|
|||
|
|
y | XXy Xyy yyy Xy yy yO
|
|||
|
|
O | XXO XYO yyO XO yO OO
|
|||
|
|
|
|||
|
|
Since at least one "X" is required (can't build a puzzle without all
|
|||
|
|
the pieces), we may immediately ignore "Yyyy", "Yyy", "yyy", "YyO",
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 7
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
"yyO", "Yy", "yy", "YO", "yO", and "OO".
|
|||
|
|
|
|||
|
|
In a like manner, "XXXY", "XXYy", and "XYyy" have too many pieces and
|
|||
|
|
are unstable, usually dying at conception, in the womb, or soon after
|
|||
|
|
birth (and invariably before puberty) from gross birth defects due to
|
|||
|
|
over-emphasis of various sex-linked traits.
|
|||
|
|
|
|||
|
|
Turner females, "XO", show all normal female characteristics save that
|
|||
|
|
they have difficulty reproducing due to the absence of a paired sex
|
|||
|
|
chromosome, which inhibits normal meiosis.
|
|||
|
|
|
|||
|
|
Kleinfelter superfemales, "XXX", tend to exhibit an unusually strong
|
|||
|
|
maternal instinct, often refusing to wean or surrender their young.
|
|||
|
|
This leads to psychological damage in the young, usually resulting in
|
|||
|
|
antisocial behavior.
|
|||
|
|
|
|||
|
|
Kleinfelter supermales, "XYy" or "Xyy", tend to exhibit a generally
|
|||
|
|
antisocial behavior, often leading to unnecessary fighting to the
|
|||
|
|
point of inhibiting mating. As an interesting aside, among us humans
|
|||
|
|
approximately 5 per cent of convicted male felons are supermales.
|
|||
|
|
Hermaphrodites, "XXy" and "XXY", have male bodies but tend to exhibit
|
|||
|
|
various female characteristics, often adopting orphan kittens or other
|
|||
|
|
young. One such cat adopted a litter of mice, which it lovingly
|
|||
|
|
raised while gleefully hunting their relatives. Hermaphrodites are
|
|||
|
|
invariably sterile, sometime having both sets of sexual organs with
|
|||
|
|
neither fully developed. This is the most common of the aberrant
|
|||
|
|
sexual makeups.
|
|||
|
|
|
|||
|
|
Pseudoparthenogenetic females, "XXO", or males, "XYO", are identical
|
|||
|
|
to normal cats in every way save that their sex and sex-linked charac-
|
|||
|
|
teristics come only from one parent.
|
|||
|
|
|
|||
|
|
Gene-reversal males, "Xy", suffer partial gene reversal, receiving a
|
|||
|
|
normal "X" from one parent and a "y" from the other parent's "X".
|
|||
|
|
This is the rarest of the aberrant sexual makeups.
|
|||
|
|
|
|||
|
|
Pseudoparthenogenetic and gene-reversal animals often suffer from
|
|||
|
|
birth defects and other signs of the aberrant genetic construct.
|
|||
|
|
|
|||
|
|
Normal females, "XX", and males, "XY", are by definition the norm and
|
|||
|
|
vastly outnumber all other type combined. Chances are less than
|
|||
|
|
1:10000 that any given cat has a genetically aberrant sexual makeup,
|
|||
|
|
the most common of which is hermaphroditism, about 1:11000.
|
|||
|
|
|
|||
|
|
Mutations
|
|||
|
|
|
|||
|
|
Going back to genes in general, those genes that are found in the
|
|||
|
|
African Wildcat, felis lybica, the immediate ancestor of our cats, are
|
|||
|
|
termed "wild." These genes may be considered to be the basic stock of
|
|||
|
|
all cats.
|
|||
|
|
|
|||
|
|
Since all cats do not look like African Wildcats (brown tabbies), it
|
|||
|
|
is obvious that some changes have taken place in the genetic codes.
|
|||
|
|
These changes occur all the time, and are called mutations. Unlike
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 8
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
the distortions shown in cheap post-apocalypse or ecological-disaster
|
|||
|
|
movies, mutations rarely occur at the gross level, but rather at the
|
|||
|
|
level of the genetic codes themselves.
|
|||
|
|
|
|||
|
|
Mutations occur when, in the course of mitosis or meiosis, there is an
|
|||
|
|
imperfect replication or joining of the components of the DNA macro-
|
|||
|
|
molecule. Such imperfections can occur as a result of a chemical
|
|||
|
|
imbalance within the body which affects replication. Most commonly
|
|||
|
|
these days such an imbalance is caused by the introduction of some
|
|||
|
|
foreign agent into the body (such as nicotine or, for an extreme
|
|||
|
|
example, thalidomide) which acts as a catalyst and affects the keying
|
|||
|
|
action of the enzymes during replication. Such agents are called
|
|||
|
|
mutagens.
|
|||
|
|
|
|||
|
|
The greatest of all mutagens is radiation. It is believed that the
|
|||
|
|
vast majority of spontaneous mutations, such as extra toes, long hair,
|
|||
|
|
albinism, etc., that keep reoccurring in an otherwise clean gene pool
|
|||
|
|
are caused by solar radiation, cosmic rays, the Earth's own background
|
|||
|
|
radiation, and most probably, by radioactive isotopes of the atoms
|
|||
|
|
making up DNA itself, most significantly carbon-14. (One of the
|
|||
|
|
dangers of nuclear war, other than the obvious, is that the increase
|
|||
|
|
in background radiation and atmospheric carbon-14 may increase the
|
|||
|
|
numbers of spontaneous mutations to the point where the germ cells
|
|||
|
|
lose viability, and whole species, even genera, would go the way of
|
|||
|
|
the dinosaur.)
|
|||
|
|
|
|||
|
|
Mutations are the very essence of evolution (or of a breeding program,
|
|||
|
|
which is merely evolution guided by man). It is through mutation that
|
|||
|
|
the survival of the fittest takes place.
|
|||
|
|
|
|||
|
|
To illustrate this, let's assume a species of striped cat living on
|
|||
|
|
the plains. He undergoes a mutation creating a spotted coat (the
|
|||
|
|
stripes get broken up). For our plains friend, the spots don't blend
|
|||
|
|
as well as stripes with the long shadows and colors of the grasses,
|
|||
|
|
his prey can see and avoid him better, and he soon evolves out. This
|
|||
|
|
was a detrimental mutation (most are).
|
|||
|
|
|
|||
|
|
Now let's assume the same species of striped cat living in woodlands.
|
|||
|
|
He undergoes the same mutation creating a spotted coat. In his case,
|
|||
|
|
the spots blend better with the dapple of light and shadow playing
|
|||
|
|
through the trees, his prey can't see or avoid him as well, and spots
|
|||
|
|
are soon the "in" thing. This was a beneficial mutation. From the
|
|||
|
|
same parent stock we soon have two differing sub-species, one striped,
|
|||
|
|
living on the plains, and one spotted, living in the woods.
|
|||
|
|
|
|||
|
|
In a domestic situation, a litter is born to two normal cats, wherein
|
|||
|
|
one of the kittens is hairless. Thinking the hairlessness is differ-
|
|||
|
|
ent enough to be a desired feature, especially for those with aller-
|
|||
|
|
gies, the kitten is very carefully bred to other cats, back and forth
|
|||
|
|
over several generations, until the hairlessness breeds true. Thus
|
|||
|
|
the Sphinx, a hairless domestic cat and the ultimate in hypo-allergen-
|
|||
|
|
ic cats, was developed.
|
|||
|
|
|
|||
|
|
The Mapped-out Genes
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 9
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
As stated earlier, a few of the common cat genes have been identified
|
|||
|
|
and mapped. These genes are grouped according to the effects they
|
|||
|
|
have: the body-conformation genes which affect the shape of the body
|
|||
|
|
of body parts; the coat-conformation genes which affect the texture
|
|||
|
|
and length of the coat; and the color-conformation genes which affect
|
|||
|
|
the color and pattern of the coat.
|
|||
|
|
|
|||
|
|
The color-conformations genes are themselves divided into three
|
|||
|
|
groups: the color genes which control the color of the coat and its
|
|||
|
|
density; the color-pattern genes which control the pattern of the coat
|
|||
|
|
and expression of the color; and the color-masking genes which control
|
|||
|
|
the degree and type of masking of the basic color.
|
|||
|
|
|
|||
|
|
The Body-Conformation Genes
|
|||
|
|
|
|||
|
|
The body-conformation genes affect the basic conformation of the parts
|
|||
|
|
of the body: ears, tail and feet. There are literally thousands of
|
|||
|
|
body conformation genes, but only a few have been mapped: normal or
|
|||
|
|
Scottish fold ears, normal or Japanese bobtail, normal or Manx tail-
|
|||
|
|
lessness and spinal curve, and normal or polydactyl feet.
|
|||
|
|
|
|||
|
|
The Scottish-fold gene: normal or folded ears. The wild allele,
|
|||
|
|
"fd", is recessive and produces normal ears. The mutation, "Fd", is
|
|||
|
|
dominant and produces the cap-like folded ears of the Scottish Fold.
|
|||
|
|
This mutant gene is crippling when homozygous.
|
|||
|
|
|
|||
|
|
The Japanese Bobtail gene: normal or short tail. The wild allele,
|
|||
|
|
"Jb", is dominant and produces normal-length tails. The mutation,
|
|||
|
|
"jb", is recessive and produces the short tail of the Japanese Bob-
|
|||
|
|
tail. Unlike the Manx mutation, this mutation is not crippling and
|
|||
|
|
does not cause deformation of the spine.
|
|||
|
|
|
|||
|
|
The Manx gene: normal or missing tail. The wild allele, "m", is
|
|||
|
|
recessive and produces normal-length tails and proper spinal conforma-
|
|||
|
|
tion. The mutation, "M", is dominant and produces the missing tail
|
|||
|
|
and shortened spine of the Manx. This mutation is lethal when homozy-
|
|||
|
|
gous. When heterozygous, it is often crippling, sometimes resulting
|
|||
|
|
in spinal bifida, imperforate anus, chronic constipation, or inconti-
|
|||
|
|
nence.
|
|||
|
|
|
|||
|
|
The polydactyl gene: normal-number or extra toes. The wild allele,
|
|||
|
|
"pd", is recessive and produces the normal number of toes. The muta-
|
|||
|
|
tion, "Pd", is dominant and produces extra toes, particularly upon the
|
|||
|
|
front paws.
|
|||
|
|
|
|||
|
|
Interestingly, humans also have a similar dominant polydactyl gene
|
|||
|
|
controlling the number of fingers. Homozygous people with six fingers
|
|||
|
|
on each hand will pass that trait on to all their children, heterozy-
|
|||
|
|
gous people to one in four of their children, even with a normal mate:
|
|||
|
|
the gene is dominant. Just because a given mutation is dominant,
|
|||
|
|
however, doesn't mean it will dominate the species. If a given muta-
|
|||
|
|
tion is not conducive to survival of the individual or inhibits mating
|
|||
|
|
in any way, it will never become "popular," no matter how dominant it
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 10
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
may be.
|
|||
|
|
|
|||
|
|
The Coat-Conformation Genes
|
|||
|
|
|
|||
|
|
The coat conformation genes affect such things as the length and
|
|||
|
|
texture of the coat.
|
|||
|
|
|
|||
|
|
The Sphinx gene: hairy or hairless coat. The wild allele, "Hr", is
|
|||
|
|
dominant and produces a normal hairy coat. The mutation, "hr", is
|
|||
|
|
recessive and produces the hairless or nearly hairless coat of the
|
|||
|
|
Sphinx.
|
|||
|
|
|
|||
|
|
The longhaired gene: short or long coat. The wild allele, "L", is
|
|||
|
|
dominant and produces a normal shorthaired coat. The mutation, "l",
|
|||
|
|
is recessive and produces the longhaired coat of the Persians, Ango-
|
|||
|
|
ras, Main Coons, and others.
|
|||
|
|
|
|||
|
|
The Cornish Rex gene: straight or curly coat. The wild allele, "R",
|
|||
|
|
is dominant and produces a normal straighthaired coat. The mutation,
|
|||
|
|
"r", is recessive and produces the very short curly coat, without
|
|||
|
|
guard hairs, of the Cornish Rex.
|
|||
|
|
|
|||
|
|
The Devon Rex gene: straight or curly coat. The wild allele, "Re",
|
|||
|
|
is dominant and produces a normal straighthaired coat. The mutation,
|
|||
|
|
"re", is recessive and produces the very short curly coat of the Devon
|
|||
|
|
Rex. Unlike the Cornish Rex, the Devon Rex retains guard hairs in its
|
|||
|
|
coat.
|
|||
|
|
|
|||
|
|
The Oregon Rex gene: straight or curly coat. The wild allele, "Ro",
|
|||
|
|
is dominant and produces a normal straighthaired coat. The mutation,
|
|||
|
|
"ro", is recessive and produces the very short curly coat of the
|
|||
|
|
Oregon Rex. Like the Cornish Rex, the Oregon Rex lacks guard hairs.
|
|||
|
|
|
|||
|
|
The American Wirehair gene: soft or bristly coat. The wild allele,
|
|||
|
|
"wh", is recessive and produces a normal soft straighthaired coat.
|
|||
|
|
The mutation, "Wh", is dominant and produces the short, stiff, wiry
|
|||
|
|
coat of the American Wirehair.
|
|||
|
|
|
|||
|
|
Note that there are three different Rex mutations producing almost
|
|||
|
|
identical effect. There are still three different genes involved,
|
|||
|
|
however.
|
|||
|
|
|
|||
|
|
The Color-Conformation Genes
|
|||
|
|
|
|||
|
|
The color-conformation genes determine the color, pattern, and expres-
|
|||
|
|
sion of the coat. Since these characteristics are among the most
|
|||
|
|
important of the cat's features, at least from a breeding point of
|
|||
|
|
view, more emphasis is given the color conformation genes than the
|
|||
|
|
others.
|
|||
|
|
|
|||
|
|
These genes fall into three logical groups: those that control the
|
|||
|
|
color, those that control the pattern, and those that control the
|
|||
|
|
color expression. Each of these groups contains several differing but
|
|||
|
|
interrelated genes.
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 11
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The Color Gene
|
|||
|
|
|
|||
|
|
The first of the genes controlling coat color is the color gene. This
|
|||
|
|
gene controls the actual color of the coat and comes in three alleles:
|
|||
|
|
black, dark brown, or light brown. This three-level dominance is not
|
|||
|
|
at all uncommon: the albinism gene, for example, has five levels.
|
|||
|
|
|
|||
|
|
The black allele, "B", is wild, is dominant, and produces a black or
|
|||
|
|
black-and-brown tabby coat, depending upon the presence of the agouti
|
|||
|
|
gene. Technically, the black is an almost-black, super-dark brown
|
|||
|
|
that is virtually black -- true black is theoretically impossible, but
|
|||
|
|
often reached in the practical sense (so much for theory).
|
|||
|
|
|
|||
|
|
The dark-brown allele, "b", is mutant, is recessive to black but
|
|||
|
|
dominant to light brown, and reduces black to dark brown.
|
|||
|
|
|
|||
|
|
The light-brown allele, "bl", is mutant, is recessive to both black
|
|||
|
|
and dark brown, and reduces black to a medium brown.
|
|||
|
|
|
|||
|
|
The Orange-Making Gene
|
|||
|
|
|
|||
|
|
The second of the genes controlling coat color is the orange-making
|
|||
|
|
gene. This gene controls the conversion of the coat color into orange
|
|||
|
|
and the masking of the agouti gene and comes in two alleles: non-
|
|||
|
|
orange and orange.
|
|||
|
|
|
|||
|
|
The non-orange allele, "o", is wild and allows full expression of the
|
|||
|
|
black or brown colors. The orange allele, "O", is mutant and converts
|
|||
|
|
black or brown to orange and masks the effects of the non-agouti
|
|||
|
|
mutation of the agouti gene (all orange cats are tabbies).
|
|||
|
|
|
|||
|
|
This gene is sex-linked -- it is carried on the "X" chromosome beyond
|
|||
|
|
the limit of the "Y" chromosome. Therefore, in males there is no
|
|||
|
|
homologous pairing, and the single orange-making gene stands alone.
|
|||
|
|
As a result there is no dominance effect in males: they are either
|
|||
|
|
orange or non-orange. If a male possesses the non-orange allele, "o",
|
|||
|
|
all colors (black, dark brown, or light brown) will be expressed. If
|
|||
|
|
he possesses the orange allele, "O", all colors will be converted to
|
|||
|
|
orange.
|
|||
|
|
|
|||
|
|
In females there is an homologous pairing, one gene being carried on
|
|||
|
|
each of the two "X" chromosomes. These two genes act together in a
|
|||
|
|
very special manner (as a sort of tri-state gene), and again there is
|
|||
|
|
no dominance effect.
|
|||
|
|
|
|||
|
|
If the female is homozygous for non-orange, "oo", all colors will be
|
|||
|
|
expressed. If she is homozygous for orange, "OO", all colors will be
|
|||
|
|
converted to orange. It is when she is heterozygous for orange, "Oo",
|
|||
|
|
that interesting things begin to happen: through a very elegant
|
|||
|
|
process, the black-and-orange tortoiseshell or brindled female is
|
|||
|
|
possible.
|
|||
|
|
|
|||
|
|
Shortly after conception, when a female zygote is only some dozens of
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 12
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
cells in size, a chemical trigger is activated to start the process of
|
|||
|
|
generating a female kitten. This same trigger also causes the zygote
|
|||
|
|
to "rationalize" all the sex-linked characteristics, including the
|
|||
|
|
orange-making genes. In this particular case, suppression of one of
|
|||
|
|
the orange-making genes in each cell takes place in a not-quite-random
|
|||
|
|
pattern (there is some polygene influence here). Each cell will then
|
|||
|
|
carry only one orange-making gene.
|
|||
|
|
|
|||
|
|
Since the zygote was only some dozens of cells in size at the time of
|
|||
|
|
rationalization, only a few of those cells will eventually determine
|
|||
|
|
the color of the coat (the orange-making genes in the other cells will
|
|||
|
|
be ignored). If the zygote were homozygous for non-orange, "oo", then
|
|||
|
|
all cells will contain "o", and the coat will be non-orange. Like-
|
|||
|
|
wise, if the zygote were homozygous for orange, "OO", then all cells
|
|||
|
|
will contain "O", and the coat will be orange. If, however, the
|
|||
|
|
zygote were heterozygous, "Oo", then some of the cells will contain
|
|||
|
|
"O" and the rest of the cells will contain "o". In this case, those
|
|||
|
|
portions of the coat determined by "O" cells will be orange, while
|
|||
|
|
those portions determined by "o" cells will be non-orange. Voila! A
|
|||
|
|
tortoiseshell cat!
|
|||
|
|
|
|||
|
|
A female kitten has two "X" chromosomes, and therefore two orange-
|
|||
|
|
making genes, one from each parent. Assuming for the sake of discus-
|
|||
|
|
sion an equal likelihood of inheriting either allele from each parent
|
|||
|
|
-- an assumption that is patently false, but used here for demonstra-
|
|||
|
|
tion only -- then one quarter of all females would be non-orange, one-
|
|||
|
|
quarter would be orange, and one-half would be tortoiseshell. A male
|
|||
|
|
kitten, on the other hand, has only one "X" chromosome, and therefore
|
|||
|
|
only one orange-making gene. Keeping the same false assumption of
|
|||
|
|
equal likelihood, then one-half of all males would be non-orange and
|
|||
|
|
one-half would be orange. This means that there would be twice as
|
|||
|
|
many orange males as females if our assumption were correct.
|
|||
|
|
|
|||
|
|
Our equal-likelihood assumption is not correct, however. The orange-
|
|||
|
|
making gene is located adjacent to the centromere and is often damaged
|
|||
|
|
during meiosis. This damage tends to make an orange allele into a
|
|||
|
|
non-orange allele, giving the non-orange allele a definite leg up, so
|
|||
|
|
to speak, in a 7:3 ratio. This means that among female kittens 49%
|
|||
|
|
will be non-orange, 42% will be tortoiseshell, and only 9% will be
|
|||
|
|
orange, while among male kittens 70% will be non-orange and 30% will
|
|||
|
|
be orange: there will be more than 3 times as many orange males as
|
|||
|
|
females. That's why there are so many Morris-type males around.
|
|||
|
|
|
|||
|
|
Since a male has only one orange-making gene, there cannot be a male
|
|||
|
|
tortie. An exception to this rule is the hermaphrodite, which has an
|
|||
|
|
"XXY" genetic structure. Such a cat can be tortie, since it has two
|
|||
|
|
"X" chromosomes, but must invariably be sterile. In fact, despite the
|
|||
|
|
presence of male genitalia, a hermaphrodite is genetically an underde-
|
|||
|
|
veloped female, and may have both ovaries and testes, with neither
|
|||
|
|
fully functional.
|
|||
|
|
|
|||
|
|
The Color-Density Gene
|
|||
|
|
|
|||
|
|
The third and last of the genes controlling the coat color is the
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 13
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
color-density gene. This gene controls the uniformity of distribution
|
|||
|
|
of pigment throughout the hair and comes in two alleles: dense, "D",
|
|||
|
|
and dilute, "d".
|
|||
|
|
|
|||
|
|
The dense allele, "D", is wild, is dominant, and causes pigment to be
|
|||
|
|
distributed evenly throughout each hair, making the color deep and
|
|||
|
|
pure. A dense coat will be black, dark brown, medium brown, or or-
|
|||
|
|
ange.
|
|||
|
|
|
|||
|
|
The dilute allele, "d", is mutant, is recessive, and causes pigment to
|
|||
|
|
be agglutinated into microscopic clumps surrounded by translucent
|
|||
|
|
unpigmented areas, allowing white light to shine through and diluting
|
|||
|
|
the color. A dilute coat will be blue (gray), tan, beige, or cream.
|
|||
|
|
|
|||
|
|
The Eight Cat Colors
|
|||
|
|
|
|||
|
|
All possible expressions of the color, orange-making, and color-
|
|||
|
|
density genes produce the eight basic coat colors: black, blue
|
|||
|
|
(gray), chestnut or chocolate (dark-brown), lavender or lilac (tan),
|
|||
|
|
cinnamon (medium brown), fawn (beige), red (orange), and cream.
|
|||
|
|
|
|||
|
|
| Sex | "BB Bb Bbl bb bbl blbl"
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
ooDD | Either | Black Black Black Chestnut Chestnut Cinna
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
ooDd | Either | Black Black Black Chestnut Chestnut Cinna
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
oodd | Either | Blue Blue Blue Lavender Lavender Fawn
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
oODD | Female | Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red
|
|||
|
|
| Male | Black Black Black Chestnut Chestnut Cinna
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
oODd | Female | Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red
|
|||
|
|
| Male | Black Black Black Chestnut Chestnut Cinna
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
oOdd | Female | Blu/Crm Blu/Crm Blu/Crm Lav/Crm Lav/Crm Fwn/Crm
|
|||
|
|
| Male | Blue Blue Blue Lavender Lavender Fawn
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
OoDD | Female | Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red
|
|||
|
|
| Male | Red Red Red Red Red Red
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
OoDd | Female | Blk/Red Blk/Red Blk/Red Chs/Red Chs/Red Cin/Red
|
|||
|
|
| Male | Red Red Red Red Red Red
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
Oodd | Female | Blu/Crm Blu/Crm Blu/Crm Lav/Crm Lav/Crm Fwn/Crm
|
|||
|
|
| Male | Cream Cream Cream Cream Cream Cream
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
OODD | Either | Red Red Red Red Red Red
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
OODd | Either | Red Red Red Red Red Red
|
|||
|
|
-----+--------+-------------------------------------------------------
|
|||
|
|
OOdd | Either | Cream Cream Cream Cream Cream Cream
|
|||
|
|
|
|||
|
|
The brown and dilute colors are rarer (hence generally more prized)
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 14
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
because they are recessive. A table of all possible combinations of
|
|||
|
|
the three genes controlling color will show all eight basic coat
|
|||
|
|
colors, among which are six female or twelve male black cats but only
|
|||
|
|
one female or two male fawn:
|
|||
|
|
|
|||
|
|
Note that although tortoiseshell females are two-color they introduce
|
|||
|
|
no new colors.
|
|||
|
|
|
|||
|
|
It may also be noted that red and cream dominate any of the true
|
|||
|
|
(black or brown) colors: a red coat is red regardless of whether the
|
|||
|
|
color gene is black, dark brown, or light brown. The color gene is
|
|||
|
|
masked by the orange-making gene. This, coupled with the fact that
|
|||
|
|
males are either red or non-red require that the color chart show "oO"
|
|||
|
|
and "Oo" as distinctly separate. A male has only the first of the two
|
|||
|
|
genes: "o" from "oO" or "O" from "Oo". In some texts, the orange-
|
|||
|
|
making genes are indicated as "o(O)" and "O(o)" to emphasize the
|
|||
|
|
sexual distinction.
|
|||
|
|
|
|||
|
|
The Albinism Gene
|
|||
|
|
|
|||
|
|
The first of the color-conformation genes affect coat pattern is the
|
|||
|
|
albinism gene. This gene controls the amount of body color and comes
|
|||
|
|
in five alleles: full color, "C", Burmese, "cb", Siamese, "cs", blue-
|
|||
|
|
eyed albino, "ca", and albino, "c".
|
|||
|
|
|
|||
|
|
The full color allele, "C" is wild, is dominant, and produces a full
|
|||
|
|
expression of the coat colors. This is sometimes called the non-
|
|||
|
|
albino allele.
|
|||
|
|
|
|||
|
|
The Burmese allele, "cb", is mutant, is recessive to the full color
|
|||
|
|
allele, codominant with the Siamese allele, and dominant to the blue-
|
|||
|
|
eyed albino and albino alleles, and produces a slight albinism, reduc-
|
|||
|
|
ing black to a very dark brown, called sable in the Burmese breed, and
|
|||
|
|
producing green or green-gold eyes.
|
|||
|
|
|
|||
|
|
The Siamese allele, "cs", is mutant, is recessive to the full color
|
|||
|
|
allele, codominant with the Siamese allele, and dominant to the blue-
|
|||
|
|
eyed albino and albino alleles, and produces an intermediate albinism,
|
|||
|
|
reducing the basic coat color from black/brown to a light beige with
|
|||
|
|
dark brown "points" in the classic Siamese pattern and producing
|
|||
|
|
bright blue eyes.
|
|||
|
|
|
|||
|
|
The Burmese and Siamese alleles are codominant, that is they each have
|
|||
|
|
exactly as much dominance or recessivity. It is possible to have one
|
|||
|
|
of each allele, "cbcs", producing a Siamese-patterned coat with a
|
|||
|
|
darker base body color and turquoise (aquamarine) eyes: the Tonkinese
|
|||
|
|
pattern.
|
|||
|
|
|
|||
|
|
The blue-eyed albino allele, "ca", is mutant, is recessive to the full
|
|||
|
|
color, Burmese and Siamese alleles and dominant to the albino allele,
|
|||
|
|
and produces a nearly complete albinism with a translucent white coat
|
|||
|
|
and very washed-out pale blue eyes.
|
|||
|
|
|
|||
|
|
The albino allele, "c", is mutant, is recessive to all others, and
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 15
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
produces a complete albinism with a translucent white coat and pink
|
|||
|
|
eyes.
|
|||
|
|
|
|||
|
|
The albanism genes combine in some rather interesting ways:
|
|||
|
|
|
|||
|
|
| C cb cs ca c
|
|||
|
|
---+-----------------------------------------------------------
|
|||
|
|
C | full color full color full color full color full color
|
|||
|
|
cb | full color Burmese Tonkinese Burmese Burmese
|
|||
|
|
cs | full color Tonkinese Siamese Siamese Siamese
|
|||
|
|
ca | full color Burmese Siamese B-E Albino B-E Albino
|
|||
|
|
c | full color Burmese Siamese B-E Albino Albino
|
|||
|
|
|
|||
|
|
Notice how the dominance characteristics among the alleles are normal
|
|||
|
|
except for the combination of Burmese and Siamese, which produce the
|
|||
|
|
Tonikinese pattern.
|
|||
|
|
|
|||
|
|
The Agouti Gene
|
|||
|
|
|
|||
|
|
The next gene controlling the pattern of the coat is the agouti gene.
|
|||
|
|
This gene will control ticking and comes in two alleles: agouti, "A",
|
|||
|
|
and non-agouti, "a".
|
|||
|
|
|
|||
|
|
The agouti allele, "A", is wild, is dominant, and produces a banded
|
|||
|
|
or ticked (agouti) hair, which in turn will produce a tabby coat
|
|||
|
|
pattern.
|
|||
|
|
|
|||
|
|
The non-agouti allele, "a", is mutant, is recessive, and suppresses
|
|||
|
|
ticking, which in turn will produce a solid-color coat. This gene
|
|||
|
|
only operates upon the color gene (black, dark brown, or light brown)
|
|||
|
|
in conjunction with the non-orange allele of the orange-making gene
|
|||
|
|
and is masked by the orange allele of the orange-making gene.
|
|||
|
|
|
|||
|
|
The Tabby Genes
|
|||
|
|
|
|||
|
|
The last of the genes affecting the coat pattern is the tabby gene.
|
|||
|
|
This gene will control the actual coat pattern (striped, spotted,
|
|||
|
|
solid, etc.) and comes in three alleles: mackerel or striped tabby,
|
|||
|
|
"T", Abyssinian or all-agouti-tabby, "Ta", and blotched or classic
|
|||
|
|
tabby, "tb".
|
|||
|
|
|
|||
|
|
The mackerel-tabby allele, "T", is wild, is co-dominant with the
|
|||
|
|
spotted tabby and Abyssinian alleles and dominant to the classic-tabby
|
|||
|
|
allele, and produces a striped cat, with vertical non-agouti stripes
|
|||
|
|
on an agouti background. This is the most common of all patterns and
|
|||
|
|
is typical grassland camouflage, where shadows are long and strait.
|
|||
|
|
|
|||
|
|
A spotted tabby is genetically a striped tabby with the stripes broken
|
|||
|
|
up by polygene influence. There is no specific "spotted-tabby" gene.
|
|||
|
|
This spotted coat is a typical forest camouflage, where shadows are
|
|||
|
|
dappled by sunlight shining through the trees. Do not confuse the
|
|||
|
|
spots of our domestic cats with the rosettes of the true spotted cats:
|
|||
|
|
entirely different genes are involved.
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 16
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The Abyssinian allele, "Ta", is mutant, is codominant to the mackerel-
|
|||
|
|
tabby allele and dominant to the classic-tabby allele, and will pro-
|
|||
|
|
duce an all-agouti coat without stripes or spots. This all-agouti
|
|||
|
|
coat is a basic type of bare-ground camouflage, seen in the wild
|
|||
|
|
rabbit and many other animals.
|
|||
|
|
|
|||
|
|
A special case occurs when both the mackerel-tabby and Abyssinian
|
|||
|
|
alleles are expressed, "TTa". This will produce a unique coat con-
|
|||
|
|
sisting of the beige ground color with each hair tipped with the
|
|||
|
|
expressed color. By selective breeding, the ground color has become a
|
|||
|
|
soft gold, producing the beautiful golden chinchilla cats.
|
|||
|
|
|
|||
|
|
The blotched- or classic-tabby allele, "tb", is recessive to both the
|
|||
|
|
mackerel-tabby and the Abyssinian alleles and will produce irregular
|
|||
|
|
non-agouti blotches or "cinnamon-roll" sworls on an agouti background.
|
|||
|
|
When the "cinnamon-rolls" are clean and symmetrical, and nicely cen-
|
|||
|
|
tered on the sides, a strikingly beautiful coat is achieved.
|
|||
|
|
|
|||
|
|
The "coat of choice" in Europe is the classic tabby (hence the name),
|
|||
|
|
probably because of the similarity in appearance of a large mackerel
|
|||
|
|
tabby domestic cat and the European Wildcat, the former being soft and
|
|||
|
|
cuddly and the latter prone to remove fingers. In the U.S., the
|
|||
|
|
reverse is true.
|
|||
|
|
|
|||
|
|
The Color-Inhibitor Gene
|
|||
|
|
|
|||
|
|
The first of the color-conformation genes controlling color expression
|
|||
|
|
is the color-inhibitor gene. This gene controls the expression of
|
|||
|
|
color within the hair and comes in two alleles: the non-inhibitor,
|
|||
|
|
"i", and the inhibitor, "Y".
|
|||
|
|
|
|||
|
|
The non-inhibitor allele, "i", is wild, is recessive, and allows
|
|||
|
|
expression of the color throughout the length of the hair, producing a
|
|||
|
|
normally colored coat.
|
|||
|
|
|
|||
|
|
The inhibitor allele, "I", is mutant, is dominant, and inhibits ex-
|
|||
|
|
pression of the color over a portion of the hair.
|
|||
|
|
|
|||
|
|
The inhibitor allele is variably-expressed. When slightly expressed,
|
|||
|
|
the short down hairs (underfur) are merely tipped with color, while
|
|||
|
|
the longer guard and awn hairs are clear for about the first quarter
|
|||
|
|
of their lengths: the coat is said to be smoked. When moderately
|
|||
|
|
expressed, the down hairs are completely clear and the longer hairs
|
|||
|
|
are clear for about half their lengths: the coat is shaded. When
|
|||
|
|
heavily expressed, the down hairs are completely clear and the longer
|
|||
|
|
hairs are clear for about three-quarters (or more) of their lengths:
|
|||
|
|
the coat is then tipped or chinchilla.
|
|||
|
|
|
|||
|
|
Neither allele has anything to do with the actual color or pattern,
|
|||
|
|
only with whether that color is laid upon a clear undercoat or one of
|
|||
|
|
the beige ground color.
|
|||
|
|
|
|||
|
|
The Spotting Gene
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 17
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The next gene controlling color expression is the white-spotting gene.
|
|||
|
|
This gene controls the presence and pattern of white masking the
|
|||
|
|
normal coat pattern, and has four alleles: non-spotted, "s", spotted,
|
|||
|
|
"S", particolor, "Sp", and Birman, "sb". The presence of the parti-
|
|||
|
|
color and Birman alleles of this gene are still subject to argument at
|
|||
|
|
this time: their effect is not.The non-spotted allele, "s", is wild,
|
|||
|
|
is recessive, and produces a normal coat without white.
|
|||
|
|
|
|||
|
|
The spotted allele, "S", is mutant, is dominant, and produces white
|
|||
|
|
spotting which masks the true coat color in the affected area. This
|
|||
|
|
is a variably-expressed allele with a very wide expression range:
|
|||
|
|
From a black cat with one white hair to a white cat with one black
|
|||
|
|
hair.
|
|||
|
|
|
|||
|
|
The particolor allele, "Sp", if it exists, is a variation of the
|
|||
|
|
spotted allele affecting the pattern of white. The classic particolor
|
|||
|
|
pattern is an inverted white "V" starting in the center of the fore-
|
|||
|
|
head and passing through the centers of the eyes. The chin, chest,
|
|||
|
|
belly, legs and feet are white. Variable expressions of this allele
|
|||
|
|
range downward to a simple white locket or a white spot on the fore-
|
|||
|
|
head.
|
|||
|
|
|
|||
|
|
The Birman allele, "Sb", if it exists, is a variation of the spotted
|
|||
|
|
allele producing white feet. Variable expression ranges from white
|
|||
|
|
legs and feet to white toes only.
|
|||
|
|
|
|||
|
|
Unlike the white gene or the albinism gene, the white-spotting gene
|
|||
|
|
does not affect eye color: if your all white cat has green eyes, it
|
|||
|
|
is most definitely a colored cat with one big white spot all over.
|
|||
|
|
|
|||
|
|
The Dominant-White Gene
|
|||
|
|
|
|||
|
|
The final gene controlling color expression is the dominant-white
|
|||
|
|
gene. This gene determines whether the coat is solid white or not,
|
|||
|
|
and comes in three alleles: non-white, "w", white, "W", and van,
|
|||
|
|
"Wv". The existence of the van allele is open to argument: it may be
|
|||
|
|
a separate gene.
|
|||
|
|
|
|||
|
|
The non-white allele, "w", is wild, is recessive, and allows full
|
|||
|
|
expression of the coat color and pattern.
|
|||
|
|
|
|||
|
|
The white allele, "W", is mutant, is dominant, and produces a translu-
|
|||
|
|
cent all-white coat with either orange or pale blue. Blue-eyed domi-
|
|||
|
|
nant-white cats are often deaf, orange-eyed cats occasionally so.
|
|||
|
|
Interestingly, a white cat may be odd-eyed, having one blue and one
|
|||
|
|
orange eye. Such a cat is often deaf on the blue side.
|
|||
|
|
|
|||
|
|
The van allele, "Wv", if it exists, is a variation of the white allele
|
|||
|
|
allowing color in the classic van pattern: on the crown of the head
|
|||
|
|
(often a two small half-caps separated by a thin white line), on the
|
|||
|
|
ears, and on the tail. Variable expression controls cap size and
|
|||
|
|
shape and the presence of color on the ears and tail. Occasionally,
|
|||
|
|
the caps will be missing and only the ears and/or tail will be col-
|
|||
|
|
ored.
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 18
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
It is important to remember that, genetically speaking, white is not a
|
|||
|
|
color, but rather the suppression of the pigment that would normally
|
|||
|
|
be present. A heterozygous white cat can an often does produce col-
|
|||
|
|
ored kittens, sometimes with no white at all.
|
|||
|
|
|
|||
|
|
Polygenes
|
|||
|
|
|
|||
|
|
The genes described above control color and coat, and several breed-
|
|||
|
|
specific body features, but what about the genes that control the body
|
|||
|
|
structure itself? Can we not develop a cat with long floppy ears
|
|||
|
|
(sort of a bassett-cat)? The answer is a qualified no. Not within
|
|||
|
|
the realms of normal breeding, and not without a much better means of
|
|||
|
|
genetic engineering than is currently available to us. The reason
|
|||
|
|
cats (and horses) resist major changes, whereas dogs do not, is be-
|
|||
|
|
cause the genes controlling these features are scattered among the
|
|||
|
|
genetic codes of other genes (remember, a gene is not a physical
|
|||
|
|
entity but rather a series of instructions). This type of scattered
|
|||
|
|
gene is called a "polygene". Polygenes are in firm control of many of
|
|||
|
|
those things that define the cat, and breeding programs can only
|
|||
|
|
change these characteristics slowly, bit-by-bit.
|
|||
|
|
|
|||
|
|
The Eye Colors
|
|||
|
|
|
|||
|
|
There are no specific genes for the eye colors. Rather, the color of
|
|||
|
|
the eyes is intimately linked to the color and pattern of the coat via
|
|||
|
|
several polygenes.
|
|||
|
|
|
|||
|
|
There is much about eye color that is not yet understood. As an
|
|||
|
|
example, the British Blue usually has orange or copper eyes while
|
|||
|
|
those of the Russian Blue are usually green, in spite of the fact that
|
|||
|
|
the breeds have identical coat genotypes.
|
|||
|
|
|
|||
|
|
The range of eye color is from a deep copper-orange through yellow to
|
|||
|
|
green. The blue and pink eyed cats are partial or full albinos, with
|
|||
|
|
suppression of the eye color.
|
|||
|
|
|
|||
|
|
Color Abr Description
|
|||
|
|
-------------------------------------------------------------
|
|||
|
|
Copper cpr Deep copper-orange
|
|||
|
|
Orange org Bright orange
|
|||
|
|
Amber amb Yellow-orange
|
|||
|
|
Yellow yel Yellow
|
|||
|
|
Gold gld Dark yellow with hint of green
|
|||
|
|
Hazel hzl Dark greenish-yellow
|
|||
|
|
Green grn Green
|
|||
|
|
Turquoise trq Bluish-green (common in Tonkinese)
|
|||
|
|
Siamese Blue sbl Royal Blue to medium-pale grayish-blue
|
|||
|
|
Dominant-White Blue wbl Medium blue
|
|||
|
|
Dominant-White Odd odd One blue, one orange
|
|||
|
|
Albino Blue abl Very pale blue, almost gray
|
|||
|
|
Albino Pink pnk Pink
|
|||
|
|
|
|||
|
|
There is a definite interaction between the color genes, "B", "b", and
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 19
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
"bl", the color density genes, "D" and "d", and eye color. This
|
|||
|
|
interaction is especially evident in those cats with Siamese coats
|
|||
|
|
where the eye color can range from a strikingly deep, rich blue for a
|
|||
|
|
Seal Point coat to a medium-pale, grayish blue for a lilac point coat.
|
|||
|
|
|
|||
|
|
Naming the Colors
|
|||
|
|
|
|||
|
|
When it came to naming the colors, those who did so were firm believ-
|
|||
|
|
ers in using the thesaurus: never call a color brown when you can
|
|||
|
|
call it chocolate or cinnamon.
|
|||
|
|
|
|||
|
|
The colors naturally fall into distinct groups: the "standard" col-
|
|||
|
|
ors, the shaded colors, the "exotic" colors, the oriental colors, and
|
|||
|
|
the whites. Each group may then be subdivided into several distinct
|
|||
|
|
smaller groups, each with a common characteristic. Each color name is
|
|||
|
|
followed by its karyotype in three groups (as they were discussed
|
|||
|
|
above), and the usual eye colors. Bear in mind that all possible
|
|||
|
|
combinations of color and pattern will eventually be realized, but not
|
|||
|
|
necessarily recognized: especially by the various cat fancies.
|
|||
|
|
|
|||
|
|
The Standard Solid Colors
|
|||
|
|
|
|||
|
|
The solids form the basis for all other colors in nomenclature and
|
|||
|
|
karyotypes: these are the fundamental rendition of the eight basic
|
|||
|
|
coat colors. Solids are called "selfs" in Britain.
|
|||
|
|
|
|||
|
|
The black solid technically has a brown undercoat, but selective
|
|||
|
|
breeding has managed to eliminate the brown undercoat and has produced
|
|||
|
|
cats that are "black to the bone."
|
|||
|
|
|
|||
|
|
The subtle differences possible in blues (grays) has made this one of
|
|||
|
|
the most popular colors among breeders, with several breeds being
|
|||
|
|
exclusively blue. Blues, regardless of pattern, are often referred to
|
|||
|
|
as "dilutes."
|
|||
|
|
|
|||
|
|
The terms "chestnut" and "chocolate" are synonymous, as are the terms
|
|||
|
|
"lavender" and "lilac."
|
|||
|
|
|
|||
|
|
Since the orange allele of the orange-making gene also masks the non-
|
|||
|
|
agouti allele of the agouti gene, red and cream solids are genetically
|
|||
|
|
identical to red and cream tabbies. Careful selective breeding has
|
|||
|
|
made cause the non-agouti areas (the stripes) to widen and overlap,
|
|||
|
|
effectively canceling the paler agouti background and obscuring the
|
|||
|
|
tabby pattern. A generation or two of random breeding, however, and
|
|||
|
|
the stripes will return.
|
|||
|
|
|
|||
|
|
The patched solids, solid-and-whites or bi-colors, are formed by
|
|||
|
|
adding the white-spotting gene, "S*", to the solids. If, instead of
|
|||
|
|
the normal random white spotting gene, the particolor gene, "Sp*", is
|
|||
|
|
present, then the coat will show white in the particolor pattern. If
|
|||
|
|
both the random white-spotting and particolor genes, "SSp", are
|
|||
|
|
present, then a composite pattern will be evident. If the Birman
|
|||
|
|
gene, "sbsb", is present, then the pattern will be white feet only.
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 20
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The tortoiseshells or torties are formed by combining both the domi-
|
|||
|
|
nant and recessive sex-linked orange genes, "Oo", with the solids.
|
|||
|
|
Because of the sex-linking of the orange genes, the tortie is always
|
|||
|
|
female. A tabby pattern may be visible in the orange areas, with any
|
|||
|
|
tabby pattern being permitted. In some individuals, the agouti and
|
|||
|
|
non-agouti orange areas may offer such contrast as to produce a false
|
|||
|
|
tri-color (black-orange-cream).
|
|||
|
|
|
|||
|
|
The patched tortoiseshells or calicos are formed by combining both the
|
|||
|
|
dominant and recessive sex-linked orange-making genes, "Oo", to the
|
|||
|
|
solids and adding the white-spotting gene, "S*". Like the torties,
|
|||
|
|
the calicos are always female, and like the patches, any white-
|
|||
|
|
spotting pattern is permitted.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
---------------------+--------------------------+----------------
|
|||
|
|
Black | B*ooD* C*aa** iissww | cpr org grn
|
|||
|
|
Blue | B*oodd C*aa** iissww | cpr org grn
|
|||
|
|
Chestnut | b*ooD* C*aa** iissww | cpr org
|
|||
|
|
Lavender | b*oodd C*aa** iissww | cpr org gld
|
|||
|
|
Cinnamon | blblooD* C*aa** iissww | org
|
|||
|
|
Fawn | blbloodd C*aa** iissww | org gld
|
|||
|
|
Red | **OOD* C***T* iissww | cpr org
|
|||
|
|
Cream | **OOdd C***T* iissww | cpr org
|
|||
|
|
---------------------+--------------------------+----------------
|
|||
|
|
Black patch | B*ooD* C*aa** iiS*ww | cpr org grn
|
|||
|
|
blue patch | B*oodd C*aa** iiS*ww | cpr org grn
|
|||
|
|
chestnut patch | b*ooD* C*aa** iiS*ww | cpr org
|
|||
|
|
lavender patch | b*oodd C*aa** iiS*ww | cpr org grn
|
|||
|
|
cinnamon patch | blblooD* C*aa** iiS*ww | org
|
|||
|
|
fawn patch | blbloodd C*aa** iiS*ww | org grn
|
|||
|
|
red patch | **OOD* C***T* iiS*ww | cpr org
|
|||
|
|
cream patch | **OOdd C***T* iiS*ww | cpr org
|
|||
|
|
|
|||
|
|
The Standard Tabby Colors
|
|||
|
|
|
|||
|
|
The tabbies are formed by adding the agouti gene, "A*", to the solids.
|
|||
|
|
This causes the otherwise solid color to show the pattern dictated by
|
|||
|
|
the tabby gene: light and dark stripes (mackerel allele, "T*") or
|
|||
|
|
blotches (blotched allele, "tbtb").
|
|||
|
|
|
|||
|
|
The brown tabby corresponds to the black solid: sufficient undercoat
|
|||
|
|
color shows in the agouti areas to provide a brownish cast. When in
|
|||
|
|
mackerel pattern, this is the "all wild" genotype, and represents the
|
|||
|
|
natural state of the cat.
|
|||
|
|
|
|||
|
|
The red tabby, when in mackerel pattern, presents an alternate stable
|
|||
|
|
coat often found on feral domestic cats, usually as a pale ginger.
|
|||
|
|
|
|||
|
|
The patched tabbies or tabby-and-whites are formed by adding the white
|
|||
|
|
spotting gene, "S*", to the tabbies. Like the patched solids, any
|
|||
|
|
white spotting pattern is permitted.
|
|||
|
|
|
|||
|
|
The tabby-tortoiseshells or torbies are formed by combining both the
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 21
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
dominant and recessive sex-linked orange genes, "Oo", with the tabbies
|
|||
|
|
colors. Like the torties, the torbies are always female.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
tortie | B*OoD* C*aaT* iissww | cpr org
|
|||
|
|
blue tortie | B*Oodd C*aaT* iissww | cpr org grn
|
|||
|
|
chestnut tortie | b*OoD* C*aaT* iissww | cpr org
|
|||
|
|
lavender tortie | b*Oodd C*aaT* iissww | cpr org grn
|
|||
|
|
cinnamon tortie | blblOoD* C*aaT* iissww | org
|
|||
|
|
fawn tortie | blblOodd C*aaT* iissww | org grn
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
calico | B*OoD* C*aaT* iiS*ww | cpr org
|
|||
|
|
blue calico | B*Oodd C*aaT* iiS*ww | cpr org grn
|
|||
|
|
chestnut calico | b*OoD* C*aaT* iiS*ww | cpr org
|
|||
|
|
lavender calico | b*Oodd C*aaT* iiS*ww | cpr org grn
|
|||
|
|
cinnamon calico | blblOoD* C*aaT* iiS*ww | org
|
|||
|
|
fawn calico | blblOodd C*aaT* iiS*ww | org grn
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
brown tabby | B*ooD* C*A*T* iissww | cpr org yel hzl
|
|||
|
|
blue tabby | B*oodd C*A*T* iissww | cpr org yel hzl
|
|||
|
|
chestnut tabby | b*ooD* C*A*T* iissww | cpr org yel hzl
|
|||
|
|
lavender tabby | b*oodd C*A*T* iissww | cpr org yel hzl
|
|||
|
|
cinnamon tabby | blblooD* C*A*T* iissww | org yel hzl
|
|||
|
|
fawn tabby | blbloodd C*A*T* iissww | org yel hzl
|
|||
|
|
red tabby | **OOD* C***T* iissww | cpr org yel hzl
|
|||
|
|
cream tabby | **OOdd C***T* iissww | cpr org yel hzl
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
brown patched tabby | B*ooD* C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
blue patched tabby | B*oodd C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
chestnut patched tabby | b*ooD* C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
lavender patched tabby | b*oodd C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
cinnamon patched tabby | blblooD* C*A*T* iiS*ww | org yel hzl
|
|||
|
|
fawn patched tabby | blbloodd C*A*T* iiS*ww | org yel hzl
|
|||
|
|
red patched tabby | **OOD* C***T* iiS*ww | cpr org yel hzl
|
|||
|
|
cream patched tabby | **OOdd C***T* iiS*ww | cpr org yel hzl
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
torbie | B*OoD* C*A*T* iissww | cpr org yel hzl
|
|||
|
|
blue torbie | B*Oodd C*A*T* iissww | cpr org yel hzl
|
|||
|
|
chestnut torbie | b*OoD* C*A*T* iissww | cpr org yel hzl
|
|||
|
|
lavender torbie | b*Oodd C*A*T* iissww | cpr org yel hzl
|
|||
|
|
cinnamon torbie | blblOoD* C*A*T* iissww | org yel hzl
|
|||
|
|
fawn torbie | blblOodd C*A*T* iissww | org yel hzl
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
torbico | B*OoD* C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
blue torbico | B*Oodd C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
chestnut torbico | b*OoD* C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
lavender torbico | b*Oodd C*A*T* iiS*ww | cpr org yel hzl
|
|||
|
|
cinnamon torbico | blblOoD* C*A*T* iiS*ww | org yel hzl
|
|||
|
|
fawn torbico | blblOodd C*A*T* iiS*ww | org yel hzl
|
|||
|
|
|
|||
|
|
The patched tabby-tortoiseshells, or patched torbies or torbicos, are
|
|||
|
|
formed by combining the dominant and recessive orange-making genes,
|
|||
|
|
"Oo", with the standard tabbies and adding the white spotting gene,
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 22
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
"S*", to the torbie colors. Like the patched solids, any white-
|
|||
|
|
spotting pattern is permitted.
|
|||
|
|
|
|||
|
|
The Shaded Colors
|
|||
|
|
|
|||
|
|
The shaded colors are formed by adding the inhibitor gene, "I*", to
|
|||
|
|
the standard solids. If the expression is light, a smoked coat is
|
|||
|
|
produced, if moderate, a shaded coat, and if heavy, a tipped or chin-
|
|||
|
|
chilla coat. Only six of the eight possible colors are recognized.
|
|||
|
|
|
|||
|
|
The tortie chinchillas are formed by adding a moderate-to heavy ex-
|
|||
|
|
pression of the inhibitor gene, "I*", to the standard torties. Only
|
|||
|
|
four of the six possible colors are recognized.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
(silver) smoke | B*ooD* C*aa** I*ssww | cpr org yel
|
|||
|
|
blue smoke | B*oodd C*aa** I*ssww | cpr org yel
|
|||
|
|
chestnut smoke | b*ooD* C*aa** I*ssww | cpr org yel
|
|||
|
|
lavender smoke | b*oodd C*aa** I*ssww | cpr org yel
|
|||
|
|
red smoke | **OOD* C***T* I*ssww | cpr org yel
|
|||
|
|
cream smoke | **OOdd C***T* I*ssww | cpr org yel
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
(silver) shade | B*ooD* C*aa** I*ssww | cpr grn
|
|||
|
|
blue shade | B*oodd C*aa** I*ssww | cpr grn
|
|||
|
|
chestnut shade | b*ooD* C*aa** I*ssww | cpr grn
|
|||
|
|
lavender shade | b*oodd C*aa** I*ssww | cpr grn
|
|||
|
|
red shade | **OOD* C***T* I*ssww | cpr grn
|
|||
|
|
cream shade | **OOdd C***T* I*ssww | cpr grn
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
(silver) chinchilla | B*ooD* C*aa** I*ssww | grn
|
|||
|
|
blue chinchilla | B*oodd C*aa** I*ssww | grn
|
|||
|
|
chestnut chinchilla | b*ooD* C*aa** I*ssww | grn
|
|||
|
|
lavender chinchilla | b*oodd C*aa** I*ssww | grn
|
|||
|
|
red chinchilla | **OOD* C***T* I*ssww | grn
|
|||
|
|
cream chinchilla | **OOdd C***T* I*ssww | grn
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
tortie chinchilla | B*OoD* C*aaT* I*ssww | cpr org yel
|
|||
|
|
blue tortie chinchilla | B*Oodd C*aaT* I*ssww | cpr org yel
|
|||
|
|
chestnut tortie chinch | b*OoD* C*aaT* I*ssww | cpr org yel
|
|||
|
|
lavender tortie chinch | b*Oodd C*aaT* I*ssww | cpr org yel
|
|||
|
|
|
|||
|
|
The Golden Chinchilla Colors
|
|||
|
|
|
|||
|
|
The golden chinchillas are formed by combining the mackerel and Abys-
|
|||
|
|
sinian alleles of the tabby gene, "TTa", with the standard solids.
|
|||
|
|
This produces a coat of undercoat-colored hairs tipped with the stand-
|
|||
|
|
ard colors. Selective breeding has altered the undercoat polygenes to
|
|||
|
|
produce a striking warm-gold color. Only three of the eight possible
|
|||
|
|
colors are recognized.
|
|||
|
|
|
|||
|
|
The golden chinchilla torties are formed by combining the mackerel and
|
|||
|
|
Abyssinian alleles of the tabby gene, "TTa", with the standard
|
|||
|
|
torties. This produces a coat with hairs of undercoat color tipped
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 23
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
with the standard tortie colors. While any combination is possible,
|
|||
|
|
only two colors are recognized.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
golden chinchilla | B*ooD* C*A*TTa iissww | gld
|
|||
|
|
honey chinchilla | b*ooD* C*A*TTa iissww | gld
|
|||
|
|
copper chinchilla | **OOD* C***TTa iissww | cpr gld
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
golden tortie chinch | B*OoD* C*A*TTa iissww | gld
|
|||
|
|
honey tortie chinch | b*OoD* C*A*TTa iissww | gld
|
|||
|
|
|
|||
|
|
The Silver Tabby Colors
|
|||
|
|
|
|||
|
|
The silver tabbies are obtained by adding a moderate expression of the
|
|||
|
|
inhibitor gene, I*, to the standard tabbies. Only six of the eight
|
|||
|
|
possible colors are recognized.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
silver tabby | B*ooD* C*A*T* I*ssww | hzl grn
|
|||
|
|
silver blue tabby | B*oodd C*A*T* I*ssww | hzl grn
|
|||
|
|
silver chestnut tabby | b*ooD* C*A*T* I*ssww | hzl grn
|
|||
|
|
silver lilac tabby | b*oodd C*A*T* I*ssww | hzl grn
|
|||
|
|
silver red tabby | **OOD* C***T* I*ssww | hzl grn
|
|||
|
|
silver cream tabby | **OOdd C***T* I*ssww | hzl grn
|
|||
|
|
|
|||
|
|
The Spotted Tabby Colors
|
|||
|
|
|
|||
|
|
The bronze spotted tabbies are genetically standard mackerel tabbies
|
|||
|
|
with the mackerel striping broken into spots by the effects of various
|
|||
|
|
polygenes. Ideal coats have evenly spaced round spots. Only six of
|
|||
|
|
the eight possible colors are recognized.
|
|||
|
|
|
|||
|
|
The silver spotted tabbies are bronze spotted tabbies with a moderate
|
|||
|
|
expression of the inhibitor gene, "I*", added. This produces a pat-
|
|||
|
|
tern of jet black spots on a silvery agouti background. Only six of
|
|||
|
|
the eight possible colors are recognized.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
bronze | B*ooD* C*A*T* iissww | gld
|
|||
|
|
bronze blue | B*oodd C*A*T* iissww | cpr gld
|
|||
|
|
bronze chocolate | b*ooD* C*A*T* iissww | cpr gld
|
|||
|
|
bronze lavender | b*oodd C*A*T* iissww | cpr gld
|
|||
|
|
copper | **OOD* C***T* iissww | cop
|
|||
|
|
bronze cream | **OOdd C***T* iissww | gld
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
silver | B*ooD* C*A*T* I*ssww | hzl grn
|
|||
|
|
silver blue | B*oodd C*A*T* I*ssww | hzl grn
|
|||
|
|
silver chocolate | b*ooD* C*A*T* I*ssww | hzl grn
|
|||
|
|
silver lilac | b*oodd C*A*T* I*ssww | hzl grn
|
|||
|
|
silver red | **OOD* C***T* I*ssww | org hzl grn
|
|||
|
|
silver cream | **OOdd C***T* I*ssww | org hzl grn
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 24
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The Abyssinian Colors
|
|||
|
|
|
|||
|
|
The Abyssinians are primarily standard tabbies with the Abyssinian
|
|||
|
|
allele of the tabby gene, "Ta*". This produces an all-agouti coat,
|
|||
|
|
similar to that of the wild rabbit.
|
|||
|
|
|
|||
|
|
The silver Abyssinians are Abyssinians with a moderate expression of
|
|||
|
|
the inhibitor gene, "I*". This produces the all-agouti ticking on a
|
|||
|
|
pale silver undercolor.
|
|||
|
|
|
|||
|
|
It should be noted that among Abyssinians there are two genetically
|
|||
|
|
different reds that are virtually identical in appearance: "red,"
|
|||
|
|
which is in reality cinnamon, and "true red," which is red.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
ruddy | B*ooD* C*A*Ta* iissww | org amb grn
|
|||
|
|
blue | B*oodd C*A*Ta* iissww | org amb grn
|
|||
|
|
chestnut | b*ooD* C*A*Ta* iissww | org amb grn
|
|||
|
|
lavender | b*oodd C*A*Ta* iissww | org amb grn
|
|||
|
|
red | blblooD* C*A*Ta* iissww | org amb
|
|||
|
|
fawn | blbloodd C*A*Ta* iissww | org amb
|
|||
|
|
true red | **OOD* C***Ta* iissww | cpr org amb
|
|||
|
|
cream | **OOdd C***Ta* iissww | cpr org amb
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
silver | B*ooD* C*A*Ta* I*ssww | grn
|
|||
|
|
silver blue | B*oodd C*A*Ta* I*ssww | grn
|
|||
|
|
silver chestnut | b*ooD* C*A*Ta* I*ssww | grn
|
|||
|
|
silver lilac | b*oodd C*A*Ta* I*ssww | grn
|
|||
|
|
silver red | blblooD* C*A*Ta* I*ssww | yel
|
|||
|
|
silver fawn | blbloodd C*A*Ta* I*ssww | yel
|
|||
|
|
true silver red | **OOD* C***Ta* I*ssww | org yel
|
|||
|
|
silver cream | **OOdd C***Ta* I*ssww | org yel
|
|||
|
|
|
|||
|
|
The Oriental Solid Colors
|
|||
|
|
|
|||
|
|
The oriental solids are identical in every way to the standard solids
|
|||
|
|
except in their names. Oriental color names tend to be used with cats
|
|||
|
|
of oriental build, effectively solid-color Siamese.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
----------------------+--------------------------+----------------
|
|||
|
|
ebony | B*ooD* C*aa** iissww | grn
|
|||
|
|
blue | B*oodd C*aa** iissww | grn
|
|||
|
|
chocolate | b*ooD* C*aa** iissww | grn
|
|||
|
|
lilac | b*oodd C*aa** iissww | grn
|
|||
|
|
caramel | blblooD* C*aa** iissww | grn
|
|||
|
|
fawn | blbloodd C*aa** iissww | grn
|
|||
|
|
red | **OOD* C***T* iissww | grn
|
|||
|
|
cream | **OOdd C***T* iissww | grn
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 25
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The Burmese Colors
|
|||
|
|
|
|||
|
|
The Burmese colors are formed from the standard solid colors by the
|
|||
|
|
reduction in color expression from full, "C*", to the Burmese alleles,
|
|||
|
|
"cbcb". This is a partial albinism and causes a slight reduction in
|
|||
|
|
color intensity: black becomes sable. These colors are used almost
|
|||
|
|
exclusively for the Burmese and related breeds, such as the Malayan
|
|||
|
|
and Tiffany.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
----------------------+--------------------------+----------------
|
|||
|
|
sable | B*ooD* cbcbaa** iissww | gld
|
|||
|
|
blue | B*oodd cbcbaa** iissww | gld
|
|||
|
|
champagne | b*ooD* cbcbaa** iissww | gld
|
|||
|
|
platinum | b*oodd cbcbaa** iissww | gld
|
|||
|
|
cinnamon | blblooD* cbcbaa** iissww | gld
|
|||
|
|
fawn | blbloodd cbcbaa** iissww | gld
|
|||
|
|
red | **OOD* cbcb**T* iissww | gld
|
|||
|
|
cream | **OOdd cbcb**T* iissww | gld
|
|||
|
|
|
|||
|
|
The Tonkinese Colors
|
|||
|
|
|
|||
|
|
The Tonkinese colors are formed from the standard solid colors by the
|
|||
|
|
reduction of color expression from full, "C*", to combined Burmese and
|
|||
|
|
Siamese, "cbcs". This is a partial albinism and causes a downgrade in
|
|||
|
|
color expression, the body color becoming a light-to-medium brown and
|
|||
|
|
the points becoming Burmese. These colors are used only with the
|
|||
|
|
Tonkinese breed.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
----------------------+--------------------------+----------------
|
|||
|
|
natural mink | B*ooD* cbcsaa** iissww | trq
|
|||
|
|
blue mink | B*oodd cbcsaa** iissww | trq
|
|||
|
|
honey mink | b*ooD* cbcsaa** iissww | trq
|
|||
|
|
champagne mink | b*oodd cbcsaa** iissww | trq
|
|||
|
|
cinnamon mink | blblooD* cbcsaa** iissww | trq
|
|||
|
|
fawn mink | blbloodd cbcsaa** iissww | trq
|
|||
|
|
red mink | **OOD* cbcs**T* iissww | trq
|
|||
|
|
cream mink | **OOdd cbcs**T* iissww | trq
|
|||
|
|
|
|||
|
|
The Siamese Colors
|
|||
|
|
|
|||
|
|
The Siamese solid-point formed from the standard colors by the reduc-
|
|||
|
|
tion of color expression from full, "C*", to Siamese, "cscs". This is
|
|||
|
|
a partial albinism and causes a downgrade in color expression, the
|
|||
|
|
body color becoming fawn and the points becoming Burmese. The solid-
|
|||
|
|
point colors are formed from the standard solids, the tortie-point
|
|||
|
|
from the standard torties, the lynx-point from the standard tabbies,
|
|||
|
|
and the torbie-point from the standard torbies. Only six of the eight
|
|||
|
|
possible solid- or lynx-point and four of the six possible tortie- or
|
|||
|
|
torbie-point colors are recognized.
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 26
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
seal point | B*ooD* cscsaa** iissww | sbl
|
|||
|
|
blue point | B*oodd cscsaa** iissww | sbl
|
|||
|
|
chocolate point | b*ooD* cscsaa** iissww | sbl
|
|||
|
|
lilac point | b*oodd cscsaa** iissww | sbl
|
|||
|
|
red point | **OOD* cscsT* iissww | sbl
|
|||
|
|
cream point | **OOdd cscsT* iissww | sbl
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
seal tortie point | B*OoD* cscsaaT* iissww | sbl
|
|||
|
|
blue tortie point | B*Oodd cscsaaT* iissww | sbl
|
|||
|
|
chocolate tortie point | b*OoD* cscsaaT* iissww | sbl
|
|||
|
|
lilac tortie point | b*Oodd cscsaaT* iissww | sbl
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
seal lynx point | B*ooD* cscsA*T* iissww | sbl
|
|||
|
|
blue lynx point | B*oodd cscsA*T* iissww | sbl
|
|||
|
|
chocolate lynx point | b*ooD* cscsA*T* iissww | sbl
|
|||
|
|
lilac lynx point | b*oodd cscsA*T* iissww | sbl
|
|||
|
|
red lynx point | **OOD* cscs**T* iissww | sbl
|
|||
|
|
cream lynx point | **OOdd cscs**T* iissww | sbl
|
|||
|
|
-----------------------+-------------------------+----------------
|
|||
|
|
seal torbie point | B*OoD* cscsA*T* iissww | sbl
|
|||
|
|
blue torbie point | B*Oodd cscsA*T* iissww | sbl
|
|||
|
|
chocolate torbie point | b*OoD* cscsA*T* iissww | sbl
|
|||
|
|
lilac torbie point | b*Oodd cscsA*T* iissww | sbl
|
|||
|
|
|
|||
|
|
The Van Colors
|
|||
|
|
|
|||
|
|
The van colors are formed from the standard solid colors by the addi-
|
|||
|
|
tion of the van gene, "Wv". This is a masking gene, covering the
|
|||
|
|
effects of the agouti, color-expression, tabby, inhibitor, and white-
|
|||
|
|
spotting genes. The van gene, a modified dominant-white gene, causes
|
|||
|
|
the coat to be white with color on the crown of the head, ears, and
|
|||
|
|
tail only. The preferred van color is auburn (orange). The tail is
|
|||
|
|
often tabby-ringed.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
----------------------+--------------------------+----------------
|
|||
|
|
black van | B*ooD* ****** ****Wv* | org wbl odd
|
|||
|
|
blue van | B*oodd ****** ****Wv* | org wbl odd
|
|||
|
|
chestnut van | b*ooD* ****** ****Wv* | org wbl odd
|
|||
|
|
lavender van | b*oodd ****** ****Wv* | org wbl odd
|
|||
|
|
cinnamon van | blblooD* ****** ****Wv* | org wbl odd
|
|||
|
|
fawn van | blbloodd ****** ****Wv* | org wbl odd
|
|||
|
|
auburn van | **OOD* ****** ****Wv* | org wbl odd
|
|||
|
|
cream van | **OOdd ****** ****Wv* | org wbl odd
|
|||
|
|
|
|||
|
|
The Whites
|
|||
|
|
|
|||
|
|
White is not a color, but rather a masking of the color genes result-
|
|||
|
|
ing in an absence of color. There are five ways a cat can have an all
|
|||
|
|
white coat: be full-inhibited white, be full-spotted white, be domi-
|
|||
|
|
nant white, be blue-eyed albino, or be albino. Each of these ways is
|
|||
|
|
genetically different.
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 27
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
The full-inhibited white coat comes from a 100% expression of the
|
|||
|
|
inhibitor gene, "I*", masking all colors and patterns. Since the
|
|||
|
|
current trend in chinchilla coats is to have just a hint of tipping,
|
|||
|
|
certain kittens are bound to be born where the "hint" is effectively
|
|||
|
|
zero, creating an all-white cat. Since the colors still exist, the
|
|||
|
|
eyes will be the proper color for the masked "true" coat colors, and
|
|||
|
|
may be anything except dominant-white blue, albino blue, or pink.
|
|||
|
|
|
|||
|
|
The full-spotted white coat comes from a 100% expression of the white
|
|||
|
|
spotting gene, "S*", masking all colors and patterns. This coat may
|
|||
|
|
have a few non-white hairs, especially on a kitten. Like the full-
|
|||
|
|
inhibited white, the eyes will be the proper color for the masked
|
|||
|
|
"true" coat colors, and may be anything except dominant-white blue,
|
|||
|
|
albino blue, or pink.
|
|||
|
|
|
|||
|
|
The dominant white coat comes from expression of the dominant-white
|
|||
|
|
gene, "W*", masking all colors and patterns. The eyes are always
|
|||
|
|
orange, dominant-white blue, or odd.
|
|||
|
|
|
|||
|
|
The blue-eyed albino comes from expression of the blue-eyed albino
|
|||
|
|
allele of the albino gene, "ca*", masking all colors and patterns.
|
|||
|
|
The eyes are always albino blue.
|
|||
|
|
|
|||
|
|
The albino coat comes from expression of the albino allele of the
|
|||
|
|
albino gene, "cc", masking all colors and patterns. The eyes are
|
|||
|
|
always pink.
|
|||
|
|
|
|||
|
|
Color | Karyotype | Usual eye color
|
|||
|
|
----------------------+--------------------------+----------------
|
|||
|
|
full-inhibited white | ****** ****** I***** | not wbl/abl/pnk
|
|||
|
|
full-spotted white | ****** ****** **S*** | not wbl/abl/pnk
|
|||
|
|
dominant white | ****** ****** ****W* | org wbl odd
|
|||
|
|
blue-eyed albino | ****** ca***** ****** | alb
|
|||
|
|
albino | ****** cc**** ****** | pnk
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
----------------------------------------------------------------------
|
|||
|
|
Feline Genetics Page 28
|
|||
|
|
|