Snap, crackle and pop Tortie Maine Coon

Tortie Maine Coon with a face framed by his ruff and ears. Photo in public domain as on Pinterest.

This is a cute, colourful bear of a cat with an amazing ruffled ruff and ginger feet. She looks young, probably still a kitten almost. Let's say a toddler or in science-speak a 'sub-adult'. We know that she is female as almost all tortoiseshells are.  You probably know that already. Tortoiseshell cats are heterozygous. They are always female except for males with certain chromosomal abnormalities. 

The action of the sex-linked orange gene O is to convert the production of black pigment (eumelanin) into orange (phaeomelanin). Tortoiseshell cats are a mosaic of orange and non-orange areas. Male tortoiseshell cats occur at a frequency of one in every 3000 male births. There are four possibilities for the occurrence of the tortoiseshell male cat. Robinson's Genetics spells out the four possibilities: somatic mutation, XXY genotype, XX and XY mosaics and chimeric cats. I don't want to try and explain those because I am not very good at cat genetics!

I had thought that male tortoiseshells are sterile but it is more complicated than that. They can be sterile and virile.

Sarah Hartwell on messybeast writes: 

"The sterility of the tortoiseshell male had frequently been remarked upon. Cutler and Doncaster (1915) showed drawings of sections of a testis of a sterile tortie male. Normal reproductive cells were absent. In summarizing the data on sterility of male tortoiseshells, they found that one was certainly fertile, 2 were completely sterile, one almost if not quite sterile, and 2 doubtful. Sterility seemed highly correlated with yellow-spotting in the male."

ASSOCIATED PAGE: Male Tortoiseshell Cat Acts like a Masculinized Female Rather Than a true Male

The best discussion on tortoiseshell cats is by Dr. Desmond Morris. He queries how male tortoiseshell cats can exist at all. He answers his own query by saying that occasionally there is a minor genetic error and a male cat develops with the genetic combination XXY. He then states that a male tortoiseshell cat's masculinity "leaves a lot to be desired". He says that to start with they are sterile and also their behaviour is "extremely odd" as they act like a "masculinized female rather than a true male". I have written about this in some more detail which you can read by clicking the link above if you wish.