Basic Feline Genetics | The Wild Woods

Basic Feline Genetics Jun 9, 2019 15:44:40 GMT -8 Chigger, Shenanigans, and 4 more like this

Post by Annie on Jun 9, 2019 15:44:40 GMT -8

commended guide award

This post has been recognized by the Community Coordinators as accurate, informative, and well written. It introduces information that can be quite complex in a user-friendly way. For this purpose, we have decided to move it into an area where more might be able to access its information and likewise commend the author and their work.

Well done!

-- Chigger

Basic Feline Genetics

Guide by Rainfalle

^{This guide was created as an informative post, and was written just for fun!
It currently only discusses the genetics of a cat's coat and its colors. Future posts may be made discussing eye colors and body mutations. Feel free to ask questions if you have any, I'll do my best to answer or find an answer for you!}

^{DISCLAIMER: I am in no way an expert in feline genetics, nor have I studied it professionally! This is simply a compilation of some of the knowledge that I have collected over a year or so of studying in my own personal down time. Sources and citations for all information used can be found at the end of this post. Thank you!}

Table of Contents
1. Differences: Male & Female
2. Dominant & Recessive Traits
3. The 3 Pelt Colors
4. The Red Variant
5. Tortoiseshell
6. Dilution
7. White Spotting
8. Tabby (Agouti) & Its Types
9. Colorpoint
10. Smoke & Silver Tabby
11. Fur Lengths & Mutations

^{If you're looking to learn more about cat genetics, I have some useful research guides linked at the bottom of this post!}

DIFFERENCES: MALE & FEMALE

Just like humans, males carry only one X chromosome, and females carry two. A male cat can be defined as XY while a female is XX. In males, the X is given by the mother and the Y by the father. Females receive an X from each parent.

A cat's color is passed only from their immediate parents. However, two cats with the same parents could look very different depending on whether they are born male or female.

A male cat can only receive colors from his mother, or their diluted variants (see Pelt Colors), because he only has one X chromosome.
A female cat receives colors from both parents, because she has two X chromosomes.

This is because the X chromosome is the chromosome that is responsible for the DNA that makes up the cat's genotype (the string of DNA that holds the cat's appearance genes, even the hidden ones, or 'carried' genes).

1. DOMINANT & RECESSIVE TRAITS

If you're familiar with DNA, you know that dominant genes are written with capitalized letters, while recessive ones are written in lowercase.

Some notes on dominant & recessive traits:

Dominant traits cannot be carried. They are either present, or they are not.
Just because a trait is recessive does not mean it is rare (for example, manx tails are dominant over regular tails).
Some recessive traits are dominant over other recessive traits.

There's much more to get into in terms of dominance and repressiveness of traits, but for the sake of simplicity, we'll leave the more in-depth details out.

Also, when dealing with genetics, Punnett Squares are your best friends. A Punnett Square essentially helps you find all possible outcomes of a certain gene between two parents. The square typically has two columns and two rows. One parent's traits go on top, filling the two columns, and the other parent's traits go on the left, filling the two rows.

Here's an example of what a Punnett Square looks like, and how it can be used:

Let's assume that the father is on top and the mother is to the left. We can see that mom is a chocolate cat that carries cinnamon (bbl), and that dad is a black cat that carries chocolate (Bb).

The square shows us the possible combinations (or kit coat colors) that can be produced from these two parents.

There are two Bb's (black, carries choc) present, which means that a kitten's chance of being black carrying chocolate is 50%.

There is one Bbl (black, carries cinn) and one bbl (choc, carries cinn) each, which means that a kitten's chance of being black carrying cinnamon OR chocolate carrying cinnamon are both 25%.

The 50% chance of Bb, 25% chance of Bbl, and the 25% chance of bbl add up to a grand total of 100%.

Because there are four squares, each square represents 25%
of the possible outcomes between the parents.

2. Pelt colors

Cats come in many different colors, as you know. However, there are actually only three base coat color classifications (referred to as eumelanin). Those three colors are black, chocolate, and cinnamon. Black is the most common, chocolate is rare, and cinnamon is the rarest. A cat can only have one base color. No more than one of the three can be present on one cat.

Each of these three coat colors have a lighter color variant, which is called dilution. Dilution essentially means that a color has been lightened. It should also be noted that dilute is a full-body gene,
which means that either a cat is completely dilute, or they aren't.

The dilute variations of black, chocolate, and cinnamon go as follows:

Black becomes blue (gray)
Chocolate becomes lilac
Cinnamon becomes fawn

To the right you can find a visual of the three colors on the left with their diluted variants, and below are pictures of cats of each of these six colors.

Black	Chocolate	Cinnamon
Blue (Gray)	Lilac	Fawn

To understand how the coat colors work with one another, here's a key for each color.

B = Black
b = Chocolate
bl = Cinnamon

Here are all of the possible combinations, and what they mean.

BB = Black
Bb = Black (carries chocolate)
Bbl = Black (carries cinnamon)
bb = Chocolate
bbl = Chocolate (carries cinnamon)
blbl = Cinnamon

3. THE RED VARIANT

By now you might be wondering where red-colored cats fit in. Interestingly, the red pelt color is completely unrelated to a cat's genetic base coat color. It is its very own entity! It should also be noted
that a cat that is red must show some tabby traits.

Like the other three pelt colors, red has a dilute variation: cream.

Below is the red color on a cat, and its dilute version, cream, on another cat.

Red

Cream

The red color gene is always dominant over the other 3 pelt colors. The red gene is also impossible to carry, which means that either a cat is red, or is not. There is no in-between—UNLESS your cat is a tortoiseshell (see following section).

4. TORTOISESHELL

A tortoiseshell (or calico) cat is a cat, usually female, whose pelt shows both her genetic coat color and the red gene. This means that her base color from one parent is visible, but one parent has given her the red gene, so it's also visible.

Tortoiseshell cats can be described as follows:

Regular tortoiseshell (black and red)
Chocolate tortoiseshell (chocolate and red)
Cinnamon tortoiseshell (cinnamon and red)
Dilute tortoiseshell (gray and cream)
Lilac tortoiseshell (lilac and cream)
Fawn tortoiseshell (fawn and cream)

These are the only six combinations of tortoiseshell. Because the dilute gene applies to both the base color and to the red gene, it is impossible, for example, to have a black and cream or a gray and red tortoiseshell (unless a pedigreed mutation occurs).

To the right you can find a visualization of the tortie types listed above. Below is an
example of each tortoiseshell type. (Note: some of these cats have white spotting.)

Regular	Chocolate	Cinnamon
Dilute	Lilac	Fawn

Here's an example breeding to show how the genes pass with red cats (to avoid confusion, dad's Y has been removed, since it has nothing to do with the colors). Assume that XX = tortie, X/XX = black, and X/XX = red.

XX mother and X father
Male offspring will either be X or X, since their X comes from their mother. She has a red X and a black X, so it could be either!
Female offspring can be either XX, XX, or XX because she gets two X's. We know that she will get a black X from her father, but she could get either a red X or a black X from mom.

Remember when we said that the X chromosome is responsible for colors? The reason males are almost never tortoiseshell is because they only get one X, which means they either have red, or they don't. They can't have both (unless they are XXY, which usually makes them infertile, or not 'true' males).

Here are three more example breedings to show the full possibilities of the red gene.

XX mother and X father
Male offspring will all be X (because mom can only give him a red X)

XX (because dad gives a black X, and mom can only give her a red X)

[/ul][/div][/font]

XX mother and X father
Male offspring will all be X (because mom can only give him a black X)Female offspring will all be XX (because dad gives a red X, and mom can only give her a black X)
XX mother and X father
Male offspring will be either X or X (because mom can give a black or red X)
Female offspring will be either XX or XX (because dad gives a red X, and mom can give a black or red X)

[/div]

5. DILUTION

So, now that you've seen the word 'dilute' pop up a few times and a few pictures of dilute cats, you might be wondering just how this odd gene works. To keep things simple, here are a few rules about dilution.

Dilution affects the entire body and all its traits. This means that you can't have a cat with the base color black and the base color gray (there are exceptions with experimental mutation breeding but it is too rare to consider it a true possibility).
Two dilute parents can only produce dilute kittens.
Two non-dilute parents can produce non-dilute or dilute kittens (for dilute kittens, they must both carry the dilute gene).

Assuming that D = non-dilute and d = dilute, let's take a look at our combinations and their possibilities.

DD = Non-dilute
Dd = Non-dilute (carries dilute)
dd = Dilute

6. White spotting

White spotting is the term used for the amount of 'white' on a cat's pelt.

Some simple rules to white on pelts:

In order for a cat to have white on its pelt, at least one parent must have white on it as well.
A solid white cat must have at least one solid white parent

A cat's parents will determine how much white a cat will or won't have on its pelt. To the right, you can find a chart showing the six most common classifications of white spotting.

No white

Both parents have no white
One parent has no white and the other has <50% white
Both parents have <50% white

Less than 50% white

One parent has no white and the other has <50% white
One parent has no white and the other has >50% white
Both parents have <50% white
One parent has <50% white and the other has >50% white

More than 50% white

One parent has <50% white and the other has >50% white
Both parents have >50% white

Now that you know a bit about white spotting, I'd like to briefly touch on dominant white cats.

Dominant white works very similarly to how the black gene interacts with chocolate and cinnamon, except that dominant white is more rare. For example, white is dominant over no white just like chocolate is dominant over cinnamon, but Dominant white is dominant over white just like black is dominant over chocolate.

For ease of use, let's use the following list to simplify all of these crazy words. The list goes from most dominant to most recessive:

Wd = dominant white
Ws = white spotting
w = no white

Here are a few example combinations of these genes, and what they mean!

WdWd = Dominant white
WdWs = Dominant white (carries white spotting)
Wdw = Dominant white (carries no white)
WsWs = 50-100% white spotting
Wsw = 0-50% white spotting (carries no white)
ww = No white

7. Tabby (agouti) & its types

This section is quite a doozy, so come prepared!

'Markings' Gene (Agouti)
The tabby or 'markings' gene is commonly referred to as agouti. When you have an agouti cat, you can determine their genetic coat color by the color of their stripes, not the color 'beneath' said stripes. Whenever a cat has the agouti gene, their fur is modified so that it is lighter in some areas, giving off the striped effect.

The agouti gene does not determine what kind of tabby a cat is, it just determines whether or not its pattern will be visible.

These are the three main agouti gene types, listed in order from most dominant to least dominant.

Apb = Bengal (this gets a little complicated!)
A = Tabby
a = Solid

With the above key in mind, there are six possible combinations of the three genes, which are...

ApbApb = "Twilight" Bengal — This gene is extremely rare and is very understudied. Best to avoid it for now.
ApbA = Tabby Bengal
Apba = Charcoal Bengal
AA = Tabby
Aa = Tabby (carries solid)
aa = Solid

Note: Bengal has a few different types, but the most popular leopard-looking kind is referred to as 'Rosette' in cats. There's also 'Marbled', which can sometimes be a bengal pattern, and lastly, there's 'Braided', which is sometimes called Toyger. See the bottom of this section for a visual of all tabby types.

Tabby Types
Now that you know what determines whether or not your cat's genetic pattern (if he/she has one), now it's time to learn about how they get their pattern, and what those patterns are and mean!

There are two main tabby types: mackerel and classic. The other two types, ticked and spotted, are variations of these two parent types.

Mc = Mackerel tabby
mc = Classic tabby

With this in mind, classic tabby is recessive because it is lowercase. The possible combinations are...
McMc = Mackerel tabby
Mcmc = Mackerel tabby (carries classic)
mcmc = Classic tabby

The Spotted Gene
The spotted gene is a modifier of the tabby gene responsible for the spotted and broken tabby types, where Sp = spotted and sp = not spotted.

SpSp = Spotted tabby
Spsp = 'Broken' tabby
spsp = Not spotted

It should be noted that the spotted gene only affects mackerel tabbies.

The Ticked Gene
The ticked gene is a modifier of the tabby gene responsible for the ticked tabby type, where Ta = ticked and ta = not ticked.

TaTa = Ticked tabby
Tata = Ticked tabby
tata = Not ticked

It should be noted that the ticked gene only affects mackerel tabbies.

Below is a chart of the aforementioned tabby types, and below that you can find real-life counterparts to all 10 types.

Classic	Mackerel	Spotted
Sokoke	Broken Mackerel	Ticked
Ticked with residual markings	Rosetted (classic bengal)	Marbled
	Candle-flame / Braided (toyger)

8. COLORPOINT

The colorpoint gene is responsible for cats that have 'points' (the appendages, ears and faces are darker than the rest of the pelt). This gene creates both solid colorpoint cats such as the Siamese breed, and lynx points when the Agouti (tabby) gene is present.

A snowshoe cat, which is considered a mink point.

Colorpoint works similarly to the way Agouti works. In pedigreed cats, it makes the majority of the body a pale, cream-white color, but leaves the appendages untouched. This is what creates the 'pointed' effect. Pedigreed pointed cats typically do not have any white spotting, with the exception of a few breeds including Mink Point, Snowshoe, and Ragdoll.

The Mink Point cat has the pointed appearance, but its body is also pale brown in color. This is because the colorpoint gene is less prominent, giving off a semi-transparent appearance. Ragdoll and Snowshoe cats work similarly.

The Sepia Point cat is very similar to the mink point. However, the difference between the two is that Sepia points become extremely rich-colored as they reach maturity, resulting in a much darker-colored cat.

FUN FACT: A pointed cat usually has blue eyes, but Sepia points can theoretically have any eye color.

Here's our chart for colorpoint gene dominance, going in order from most dominant to least dominant.

C = Not pointed
cs = Colorpoint
cb = Sepia point

With that in mind, here are our combinations and what they each mean.

CC = Not pointed
Ccs = Not pointed (carries colorpoint)
Ccb = Not pointed (carries sepia point)
cscs = Colorpoint
cscb = Mink point
cbcb = Sepia point

Knowing that the colorpoint trait can be carried, you now know that two non-pointed cats that carry colorpoint can produce a pointed kitten! You also know that two pointed cats cannot produce a non-pointed kitten.

NOTE: If your cat is solid (no tabby gene), it will appear as a regular point. If the cat does have tabby, it will be a lynx point!

Here are our examples of the three types!

Colorpoint

Mink point

Sepia point

Additionally, here's a lynx point cat for reference!

9. Smoke & silver tabby

Smoke cats and Silver tabbies are results of the Inhibitor gene. Like the red gene, inhibitor is predominant over the other colors, including red.

This gene is thought to remove pigment from a cat's fur, resulting in the grayscale colors that Smokes and Silvers display. This gene is also responsible for the pedigreed Chinchilla cat, and for shaded cats.

Whenever a cat has agouti (tabby) and the inhibitor gene, it becomes a silver tabby. If a cat is solid (no agouti) and has the inhibitor gene, it becomes a smoke.

As a rule of thumb, the paler the silver and the darker the black, the rarer the cat is, and it is more likely to be bred that way specifically.

Smoke

Silver tabby

Chinchilla

Shaded

There are, however, 'smoke tabbies', which are essentially just silver tabbies whose silver 'undercoats' are not brightened quite as much.

To the left is a 'smoke tabby', and to the right is a silver tabby.

The inhibitor gene goes as follows:

I = Silver
i = Non-silver

Here are the possible combinations as well as their meanings:

II = Silver
Ii = Silver (carries non-silver)
ii = Non-silver

10. FUR LENGTHS & MUTATIONS

There are two genetic lengths to a cat's fur, even though there are many different tangible lengths. Those two lengths, as you probably know, are long haired or short haired.

Short haired cats can range from the sleek coats of Oriental cats to your everyday medium-furred house cat. Long haired cats can range from the extremely long and dense coats of Maine Coons and Persians to a house cat whose fur is a little longer than average!

The short haired gene is dominant, and the long haired gene is recessive.
Keeping in mind that L = Short haired and l = long haired, there are three combinations:

LL = Short haired
Ll = Short haired (carries long)
ll = Long haired

There are also a number of mutations that can occur in regards to a cat's pelt. A few of those include Cornish Rex (wavy fur), hairless (absence of fur), LaPerm (stringy, unruly looking fur), and Wirehair (curly fur).

There's a lot more to get into in terms of fur types, but I'll leave it up to you to do some more research if it interests you!

www.eurocatfancy.de/en1/nav/cat-genetics/gene_I.html
www.ladymarycats.com/news_20.html
felinegenetics.missouri.edu/feline-research-projects/silver-and-golden

Looking to learn more about feline genetics?

There are so many wonderful websites containing loads of information on feline genetics! If it's something you have an interest in, one of my all-time favorite sites to study and learn from is www.eurocatfancy.de/.

This website is accessible world-wide, which means that many different sources have contributed to their info pool. It has a ton of useful information from definitions to in-depth topics as well as information on almost all cat breeds, and it goes much further into detail on the information I touched on in this post.

I absolutely recommend it as a reference source!

Another source that has been extremely useful to me is sparrows-garden.com/. Their website is still a work in progress, but they have a fantastically useful kitten coat calculator where you can enter the genetic information of both parents and it will tell you the possible outcomes of your litter. (At the time of this post, I believe that their generator is bugged as it does not include the fur lengths. Regardless, it is a good resource!).

[/div]

^{coding (c) Rainfalle
Citations listed above}