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Author: Sarah Giers
Genetics are what make a rabbit, or any living organism,
look the way it does. It makes a rabbit be a certain size,
be a certain colour, have a certain type of coat or ears,
and more.
This introduction, however, is just for the genetics concerning
the coat colours of rabbits. Chromosomes and Genes
Chromosomes are strands of DNA that act as a map. They map
out exactly how the rabbit will look. In each cell, inot including
the sex cells and red blood cells, a rabbit has 22 chromosomes.
Each one of these pairs controls a different thing about the
rabbit. For example, one might control the rabbits gender,
some control colour, others control fur. Each chromosome pair
has two genes in it. These genes may be the same, or they
might be different, but there are always two (unless there
is a genetic mutation, but we will not discuss that here).
For example, a rabbit might have two genes for blue eyes.
Conversely, a rabbit might have one gene for red eyes, and
one gene for brown eyes.
If a rabbit has two of the same type of genes in a certain
chromosome pair, it is referred to as being homozygous for
that particular gene. If it has two different genes in a certain
chromosome pair, it is referred to as being heterozygous.
If a rabbit is heterozygous, one of the genes is usually
stronger than the other. That means that the stronger gene
will be the one to cause the effect n the rabbit, and the
weaker one will just hide, though it can still be passed on
to the rabbit's offspring. Stonger genes are referred to as
being dominant, and
weaker genes are called recessive. For example, if a rabbit
had one gene for red eyes and one gene for brown eyes, the
rabbit would have brown eyes because the gene for brown eyes
is dominant to the gene for red eyes. For a rabbit to have
red eyes, it would have to be homozygous for red eyes, since
the
gene for red eyes is the most recessive.
Sometimes certain genes are not really stronger or weaker
than another. These genes are referred to as being incompletely
dominant to each other. This means if two different genes
that were incompletely dominant to each other were in the
same rabbit, the rabbit would have traits from both genes.
In
flowers, and example of an incompletely dominant gene can
be found when you breed a white flower and a red flower and
you get a pink flower.
Colour Genes
Each variety of rabbits requires many genes in order to look
the way they look. Certain genes are related, and they are
all found on the same are of the DNA strand. These groups
of genes are called loci, or locus if it is just one.
You may have seen some genetics stuff written with a bunch
of ABC's and other letters. Well, those are how various loci
and genes are written. Genes have their own alphabet. When
the "letters" of the genetics alphabet are all put
together, it is referred to as the rabbit's genotype. This
is basically a list
of all the colour genes that rabbit has, or at least the ones
that are important to understanding that particular variety.
A LOCUS
The first "letter" in the genetics alphabet is
"A." This determines the basic pattern of the rabbit.
The genes are as follows:
A: Agouti Pattern - These rabbits have tan, white, or fawn
markings on the belly, underside of the tail, inside of the
feet and legs, inside the ears and nostrils, around the eyes,
and in the shape of a triangle at the nape of the neck. On
the body, the fur has rings of different colours when you
blow into the coat.
a(t): Tan Pattern - Like agouti pattern, these rabbits have
tan, white, or fawn markings on the belly, underside of the
tail, inside of the feet and legs, inside the ears and nostrils,
around the eyes, and in the shape of a triangle at the nape
of the neck. However, the body does not have the different
colour
rings when you blow into the coat.
a: Self Pattern - Each hair is a solid colour, and there
are no tan, white, or fawn markings.
B LOCUS
"B" is the next "letter". This "letter"
tells the rabbit how intense the colour of the fur is. The
genes are as follows:
B: Black - The rabbit is black based, meaning the base colour
is black or blue.
b: Brown - The rabbit is brown based, meaning the base colour
is chocolate or lilac.
C LOCUS
"C" is the next "letter". This "letter"
tells the rabbit whether or not to have red colouring, as
well as how deep and dark the base colouring is. The genes
are as follows:
C: Full Colour - The red colouration of the fur is full expressed,
and the base colouring is also fully expressed.
c(chd): Chinchilla Dark - All red colouration is removed
from the coat, but the base colouring is still fully expressed.
c(chl): Chinchilla Light - All red colouration is removed
from the coat, and the base colouring is ightened, causing
darker shading around the head, ears, tail, feet, and legs.
c(h): Californian - All red colouration is removed, and the
base colouration is restricted to the nose, ears, feet, legs,
and tail. The eyes are red.
c: Albino - All colour is restricted, leaving a pure white
rabbit with red eyes.
D LOCUS
Next in the genetics alphabet is "D". This "letter"
determines how much pigment is in each hair shaft. The less
pigment there is, the lighter the colour is. The genes are
as follows:
D: Dense - Full amount of pigment
d: Dilute - The pigment is less, causing the colour to look
diluted.
E LOCUS
The "letter" "E" controls the banding,
or colour rings (remember in agoutis where you can see the
rings when you blow into the coat?) of a rabbit. The genes
are as follows:
E(s): Steel - The undercolour is extended and "takes
over" the colour, leaving a mostly solid coloured rabbit
with some gold or silver tipped hairs.
E: Full-Extension - The rabbit has normal colour, and the
bands are not disturbed.
e(j): Japanese - This takes the bands and actually seperates
the band colour into different hair shafts. This is how Tricolourr
and Harlequin are produced.
e: Non-Extension - There is no colour extension, leaving
only what would be the intermediate band in a normal coloured
rabbit. This is how Oranges, Frosed Pearls, and Tortoises
are produced.
EN LOCUS
The "En" "letter" controls a different
type of pattern. The genes are as follows:
En English Spotting - The rabbit is white with coloured spots.
en: Solid - The rabbit has no spots.
V LOCUS
"V" is the next "letter" in the genetic
alphabet, and for most breeds, no more of the alphabet is
needed to know the variety.
This tells whether or not the rabbit is a Blue Eyed White.
V: Non-Vienna - Normal coloured rabbit.
v: Vienna - Blue Eyed White.
W LOCUS
This "letter" is rarely included in the genotype
because it is not very important in most varieties, though
all varieties DO use it.
W: Non-Wideband - Normal colouring.
w: Wideband - The red colour becomes very intense, the intermediate
band widens, and the red colour "takes over" all
tan pattern and agouti markings so that instead of being cream
or white, they are red.
SI LOCUS
This "letter" is another that is rarely included
in the genotype. All non-silver rabbits do not need this included
in their genotype in order to let the viewer know that the
rabbit is not silver.
Si: No-Silver - Normal colouring.
si: Silver - Silver-white hairs are scattered throughout
the normal colouring.
DU LOCUS
This "letter" is usually only used when refering
to the breeds Dutch, Dwarf Hotot, and Hotot.
Du: Non-Dutch - Normal colouring.
du(d): Dutch Dark - Dutch markings, mostly coloured rather
than white.
du(w): Dutch White - Dutch markings, mostly white rather
than coloured.
Genotypes
In order to have a full knowledge of the variety of a rabbit,
just by looking at the genotype, a full genotype, using all
of these loci. For example, a Chestnut Agouti would be denoted
as A_ B_ C_ D_ E_ enen V_ W_ Si_ Du_. The spaces just mean
that a recessive gene could be there, hidden by the dominant
gene.
However, most people know that the shortened form of the genotype,
A_ B_ C_ D_ E_ enen, also means Chesntut Agouti.
About the author:
Breeder and exhibitor of show rabbits for 11 years, member
of the American Rabbit Breeders Association, and fan of all
animals. |
