Feline fur genetics explained by expurrts to a curious cat pawrent, after observing her cat's unique coat color patterns.

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    Is my cat a black tabby or a black cat? Shes about 11 years old, found as a stray.
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    I'm curious because the striping I see in the first picture only shows up in bright light but she doesn't sun herself much ( prefers my heating vents) so I don't think it's sun bleaching.
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    Also she has these singular white hairs speckled throughout her coat and a very small patch in- between her back legs. All four paws have black skin. The
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    vet didn't make note of any irregularlarites during her spay so I think she has a basic XX chromosome.
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    lipstick_spit solid black. fun fact: all cats are naturally. tabbies as in, their fur and genetic build is made to be a tabby. the difference is that if a (typical, tabby) cat has two copies of the recessive "solid" gene, then
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    they overproduce eumelanin and turn black! the solid gene is a masking gene that turns the "background" (agouti) hair between the stripes black as well, like a kind of overflow of the stripes. genetically, this is
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    caused by a mutation on the agouti signaling protein to... stop signaling agouti. lol. however, you still have the pattern that the cat was "meant" to be written in the skin. think of the clear patterns of melanistic jaguars, for example!
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    (though cats and jaguars have their respective mutations on separate genes).
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    this is why you will often see phantom markings in black cats, and why black smoke cats will get a pseudo-tabby pattern along their pelt―
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    theyre following the genetic pattern already laid out, that is just hidden from us! it is also why every red cat is visually a tabby. theyre not producing eumelanin, because they are red, and so the masking effect of the solid gene doesnt end up strong enough to cover the stripes.
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    the white hairs are normal. just little malfunctions of melanin production. the white on the belly might be. low white spotting or a locket (which is also a small malfunction of melanin production).
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    Flimsy-Lengthiness48 OP Thank you for the detailed answer! I was originally asking because I had read somewhere that a solid color female cat was actually rare because they require a homozygous 'solid' gene, whereas a black tabby was more along the lines of black panther. Still patterned just with more melanin.
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    That, plus I can only see my cat's patterns on her chest, forelegs, right flank and tail made me think she was a black tabby.
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    lipstick_spit it seems like youre maybe getting a few things mixed up here!
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    the first of which is that a black tabby is probably what youre thinking of as a "brown" tabby. these are black cats, genetically, because that is the color of eumelanin they are producing. you can determine this visually by the stripes, because there is no agouti banding to muddle it visually. the darkest black tabby
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    youre going to see would be a sheeted marbled bengal... anything more black than that (with no agouti banding, and no countershading giving the cat eyeliner, a lighter muzzle, a light belly and paws, and a light undertail, as seen in this black tabby) is not a tabby at all. i suspect you are thinking of said ghost striping, which is
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    often most visually striking in smokes and kittens. the solid gene is fully recessive to tabby, and requires two copies of the solid allele to present as solid... even if there are markings peeking through.
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    the second of which is where sx comes into play with cat colors. there are two "bases" for cat color: red-based (this is red and cream) and black-based (this is black, chocolate, cinnamon, and all of their dilutes). the mutation for red- based is on the x-chromosome. if a cat has one x-chromosome (males, typically), this is easy!
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    they either get an x-chromosome from their mother with the red mutation, making them red-based, or they dont... making them black- based. it gets a little more complicated with two x-chromosomes. they get one from their father, and one from their mother. if those two X-
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    chromosomes are both red-based, the female cat is red. if both are black-based, the female cat is black. but, they also have the additional option of receiving one red-based x- chromosome and one black-based x- chromosome. this is where the tortoiseshell pattern comes in! if a cat is heterozygous for the red mutation, they present both colors (due to lyonization, which is a bit much to get into here).
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    this is just the base color, every other modification is built upon this and is not sox- linked. this includes solid vs agouti, tabby pattern, dilute vs dense, colorpoint, corin mutations, the inhibitor mutation... literally
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    everything else is separate from the red vs black base color determined by the x-chromosome. so, a female cat having the black base color (including being a black tabby, seal point, golden chinchilla, etc) is only less common than
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    a male cat having the black base color because she had three "base color" options (red, black, and tortoiseshell) while a male only had two (red, black). so its more of a 33-33-33 distribution than a 50-50 distribution... in a perfect population where each color is equally present.
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    hope this was clear. its kind of a crash course, so feel free to ask questions.

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