Genetics: Part 2

Colour prediction

Ok, now to colour prediction at last. There are two ways to do this. The first is to look at a cat’s pattern and work through it until you reduce the genes to the dominant red or black (remember, every pattern is made from these colours). This is called de-construction. The second way is to take the cat and begin with black or red, adding the modifier genes until you come up with the existing pattern. This is often what we breeders have to do to work out the possibilities for colour and pattern from specific matings. I will give you examples of each and talk you through how to do them. I’ll start with de-construction, as it’s probably a bit easier. I’ll concentrate on tabbies, colourpoints and bicolours as these are easier to get to grips with.

Deconstruction

• 1. A blue tabby. First of all, remove the tabby gene. This leaves you with a blue cat. Then remove the dilute to leave black.




• 2. A cream and white bicolour. Remove the bicolour to leave a cream, then remove the dilute to leave red.




• 3. A blue tortie colourpoint. Remove the colourpoint to leave a blue-cream tortie. Remove the dilute to leave tortie.




• 4. A white. Remove white to get… Anything is possible. Remember, white masks any colour or pattern combination.




• 5. A lilac tabby colourpoint. Remove the tabby to leave a lilac colourpoint. Remove the colourpoint to leave a lilac. Remove the chocolate to get blue. Remove blue to get black.

Construction

• 1. A cream tabby. Add dilute to red to get cream. Add tabby to cream to get cream tabby.




• 2. A blue and white bicolour. Begin with black. Add dilute to get blue, then bicolour to get a blue and white bicolour.




• 3. A blue-cream tabby colourpoint. Begin with tortie, red and black. Add dilute to get blue-cream. Add tabby to get a blue-cream tabby. Add colourpoint to get a blue-cream tabby point (also called a blue tortie tabby point).




• 4. White. Start with black or red, and add anything you like. As long as you finish with adding white, the cat will appear white, no matter its genetic colouring or patterning.




• 5. A red chocolate colourpoint. (Remember, chocolate only modifies the black gene. This cat would actually be seen as a red colourpoint). Start with red. Add chocolate to get red chocolate (this will appear to the eye as still a red cat). Then add colourpoint to get a red choc colourpoint. Note: The cats would be classed by registering bodies as red colourpoints despite carrying two copies of the chocolate gene.

Notice that in the last examples, I have avoided black colourpoints. This is because, when a cat is pointed, the black gene is called by a different name. It is called a seal. It is the same gene and behaves the same way, but is just known as a different name.

The challenge

As a breeder or owner of a pregnant cat, you will need to be able to generate colour/pattern possibilities based on the pattern and colour of the mother and father. To this end, I am going to leave you with the colours and patterns involved in Tia’s mating. I’d love to see if you can come up with the colours of kittens she might produce. Do remember though that torties or blue-creams are usually only female. Also remember that a tortie mother can pass on either black or red to her offspring, while the father can only pass on one colour.





Tia is a seal tortie colourpoint carrying dilute and chocolate. Remember, seal means black. So in simple terms, she is a tortie colourpoint carrying dilute and chocolate. The father is a cream colourpoint who does not carry chocolate. So, what colour kittens will she produce? For the really enterprising among you, I’d like to know whether they will carry chocolate/dilute as well. I’ll tell you the answer in tomorrow’s post. For those of you that read regularly, you may already have seen it!





To help you, I will outline the mating combinations of Tia’s parents.

Mother: blue tortie tabby carrying colourpoint.

Father: chocolate colourpoint.





De-construction:

Mother: remove tabby to leave blue tortie, and dilute to leave tortie.

Father: Remove colourpoint to leave chocolate, and chocolate to leave black.





Combinations:

All kittens will carry dilute, as the mother has two copies and the dad has none.

Therefore, blues, creams or blue-creams are not an option, because no kitten will get two copies of the dilute gene.

All kittens will carry colourpoint as the dad has two copies. Colourpoint kittens are a possibility if the mother passes on her single copy to offspring.

If the mother carries two tabby genes, all offspring will be tabby. I know Tia’s mother did not, which means tabby is a possibility as she only carries one copy of this dominant gene.





Girl kittens: black, black tabby, seal colourpoint, seal tabby colourpoint, tortie, tortie tabby, seal tortie colourpoint, seal tortie tabby colourpoint.





Boys: black, black tabby, seal colourpoint, seal tabby colourpoint, red, red tabby, red colourpoint, red tabby colourpoint.





Note that boys are not torties, and that boys can be solid red where girls cannot. This is because the father always passes a black gene. Girls, because of their x chromosomes can express both black and red at the same time, but for the boys, it is the mother who has the final say on colour, hence the ability for her red to be expressed. This is because it is the mother who passes on the X chromosome and the father the Y. Remember that the colour genes are on the leg of the chromosome missing from the y.





I hope this has been helpful, and sorry it’s been so long and confusing!