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Recently, I have often come across the fact that cat breeders, both beginners and experienced, cannot determine what colors of kittens are expected from a particular mating. And this is very sad, because the genetics of cat colors is the basis that every breeder should know.

But in fact, it is not so difficult to determine the colors of future kittens, if the colors of their parents are known and if you know and remember a number of rules for cats color inheritance.

Let's remember school biology.

As we remember, a gene is a carrier of a unique set of characteristics of each organism. Genes are grouped into chromosomes, and each gene has its own place (locus) on the chromosome. Chromosomes are always paired, because they are inherited from mom and dad. A cat has 19 pairs of chromosomes, one of which is sexual, it determines whether a kitten will be a male or a female.

Genotype and phenotype.

The Phenotype - these are the signs that are visible visually. For example, a long-haired cat, or a black cat.

The Genotype is something that is not visually visible in the cat, but the cat carries these signs in the genes. For example, a short-haired cat, but a carrier of long hair.

Dominant and recessive genes.

Genes can be dominant ("strong") and recessive ("weak"). The dominant gene always suppresses the recessive one, in this case the trait for which this gene is responsible will always manifest itself in the cat.

  1. The dominant gene is always manifested, regardless of the presence or absence of a recessive allele.
  2. The recessive gene manifests itself only in the paired state.

Dominant genes are denoted by a capital letter, recessive ones by a small one.

Dominant and resessive genes

Which genes of cat's coat colors are dominant, and which are recessive?

Let's consider the basic genes of cat's coat colors. The arrows show the order of dominance.

The basic genes of cat's coat colors and the order of their dominance
Dominant Recessive   Description
А (agouti)  а (non-agouti) Agouti
Determines whether the cat will be with or without a pattern
B (black)  b (chocolate)  bl (cinnamon) Black
Determines whether the cat will be black, chocolate or cinnamon
C (non-albino, non-colorpoint)  cb (Burmese color)  cs (Siamese color)  ca (Albino with blue eyes)  c (Albino) Colorpoint Restriction
Determines whether the cat will have maximum pigmentation, or will have variants of point color, from Burmese to Albino.
D (non-lightened color)   d (lightened color) Dilution
Determines whether the cat will have lightening (blue, cream, lilac, fawn)
I (Silver, smoky)  i (non-silver) Inhibitor
Determines whether the cat will have full pigmentation and will be silvery, smoky, chinchilla
O (red, sex-linked)  o (non-red) Orange
Determines whether the male is red and the female is red or tortoiseshell
S (white spots)  s (without withe spots) Piebald Spotting
Determines whether there will be white spots on the cat or not
Ta (Abissinian color) (Tiger, mackerel)  tb (blotched tabby) Tabby
Determines what type of pattern the cat will have
(white)  (non-white) White
Determines whether the cat will be completely white or not

Maine Coons are always black (BB) and CC (non-albino, non-point). Although Maine coons with color-point are already born, this means that, contrary to the prohibitions on interbreeding, coons are mating with Neva masquerade and other breeds, carriers of the point color.

Let's look at this in the simplest example. Agouti gene (A). It determines whether the cat will have a pattern or not.

Black solid Maine Coon kitten

The Agouti gene is dominant. We remember that a cat inherits genes from mom and dad, so this sign can be written like this:

АА - the cat has a pattern
Аа - the cat has a pattern, but is a carrier of non-agouti
аа - the cat's coat is solid

If a gene has 2 identical alleles (AA or aa) -it is called homozygous, if Aa - then heterozygous.

Draw! The Punnett Square is your helper.

What kitten's coat color will turn out if you cross a black male (non-agouti) and a black patterned female (agouti)?

Here, the Punnett Square help us understand all possible variants of crossing this gene. Dad's genes are always indicated horizontally, mom's genes are indicated vertically.

Dad is a solid black cat and has the aa genotype

Let's mate him with black patterned cat with AA genotype - Agouti-homozygous.

Maiting cats: solid male and tabby females Maiting cats: solid male and tabby females

As you can see, all kittens from this pair will have some kind of pattern, while all will be carriers of a solid color.

And now let's mate one of these kittens with a black solid partner.

Maiting cats: solid male and tabby females Maiting cats: solid male and tabby females

From such a crossing, we got both patterned kittens and kittens with a solid color.

Questions:

  • Can two patterned parents give birth to a solid kitten? Yes, they can, if their genotype is Aa
  • Can two solid parents give birth to a kitten with pattern? No, they can't, because their genotype is aa and there is nowhere for the dominant agouti gene (the pattern gene) to come from.

Conclusions:

  • Offsprings with a dominant gene must have at least one parent with a dominant gene;
  • Dominant signs don't skip a generation. For example, a silver kitten or a smoke kitten cannot be born from two non-silver partners, as well as two solid parents cannot give birth kittens with pattern;
  • The manifestation of recessive genes is possible after a generation or generations. Two black partners can give birth to a blue kitten if both are carriers of lightening.

But there are a lot of cat's color genes!

Gregor Johann Mendel. By the way, Mendel was a priest, from 1856 to 1863 he conducted experiments on peas in the monastery garden and formulated laws explaining the mechanism of inheritance.

Well, you say, with one gene it is more or less clear, but how to add all the cat's color coat genes to this Punnett Square? Do I have to draw a huge table with all the color's genes?

And here is the third law of Mendel help us.

The law states that each sign is inherited independently of each other.

Thus, you can safely make crossing options for each gene separately - separately for the presence of silver, separately for the type of pattern, etc.

What to do with the red color?

I have already mentioned that cat's red color is sex-linked.

Males can be either red or black, females can be both red and black at the same time. This cat's color is called tortoiseshell (tortie).

A female has a set of XX chromosomes, and a male has XY.

To calculate descendants from parents with red color, the sex of the cat is always added. In cats, only the X chromosome determine what color the cat will have, so the color is always recorded next to x-chromosome.

XOY - red male
XBY - black male
XOXO - red female
XBXB - black female
XOXB - tortishell female

Let's cross a red male with a black female using a Punnett Square.

Red male and black female

Maiting cats: red male and black femaleMaiting cats: red male and black females

As you can see, we got only black males, and only tortoiseshell females.

Let's change the colors of the parents and cross a black male and a red female

Black male and red female

Maiting cats: black male and red femaleMaiting cats: black male and red female

As a result, we got only tortoiseshell females again, and only red males.

Well, let's cross a tortoiseshell female and a black male.

Black male and tortoiseshell female

Maiting cats: black male and tortie female Maiting cats: black male and tortie female

From such a crossing we will get a lot of different of colors - males will have black color or red color, females will have black color or tortoiseshell color.

Cat's coat color formula.

The color of each cat can be written using the color formula, which will describe the state of each of the genes.

For example, one of the most common colors of Maine Coons is black blotched tabby with white (MCO n 03 22)

You can read more about the Maine Coons colors here.

So

Maine Coon male Russia black tabby blotched with white

  • He is a male with A_ (we don't know the condition of the other allele)
  • He is a black BB
  • He doesn't have point color CC
  • He doesn't have blue color D_ (we don't know the condition of the other allele)
  • He is not a silver ii
  • He has blotched tabby pattern tbtb
  • He has white spots S_ (we don't know the condition of the other allele)
  • He is not a red XBY
  • He is not a white solid ww

Thus, the formula of black tabby blotched with white Maine Coon is: 
A_ BB CC D_ ii tbtb S_ XBY ww

Let's cross it with a blue-tortie female (g).

  • She is a solid aa
  • She is a black BB
  • She doesn't have point color CC
  • She is lightened dd
  • She is not a silver ii
  • We don't know the female's pattern, because she is solid- ?? The patterns of the kittens will tell us what type of pattern the female has.
  • She doesn't have white spots ss
  • She have tortoiseshell color XBXO
  • She is not a white solid ww

The formula of  blue tortie Maine Coon female is: 
aa BB CC dd ii ?? ss XBXO ww

кошка мейн-кун голубокрмовая черепховая

The same set of genes can be neglected. What color kittens can be born:

A_/aa - kittens can have pattern and can be solid. If kittens with a solid color are born, then the genotype of the male is Aa

D_/dd - kittens can have both black and blue, if the cat is a carrier of a lightened color. If kittens with a lightened color (blue, cream, blue, cream) are born, then the genotype of the male is Dd.

tbtb/?? - kittens can be either tabby blotched, tiger and ticked.

S_/ss - kittens can be either with or without white spots. If kittens are born without white spots, then the genotype of the male is Ss.

XBY/XBXO - tortoiseshell females, black females, red males, black males are possible

And now make possible options out of all this.

As you can see, cat's coat genetic is quite simple.

We remember about recessive and dominant genes, we remember about the independent inheritance of genes, and we love the Punnett Square.

Then you can easily calculate the possible kitten's colors.

We have a cat's coat color genetics calculator on our website that will help you calculate possible colors of kittens (only for the Maine Coon cats).

Thank you for your attention and remember that it's never too late to learn)

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