Why are orange tabbies almost always male while calicos and tortoiseshells always female?
The majority of the time, orange and white tabby (striped) cats are male, while calico (orange or black, with white large “piebalding” patches) or tortoiseshell cats (varieties of white, black, and orange with no white patches) are female. This is due to the complicated sex-linked color gene.
Before we get into sex and genes and colors, know that some veterinarians are cat color biased. For years, veterinarians had mysteriously hypothesized that these color patterns were also linked to the friendliness gene. Interestingly enough, we may now have the scientific research to support this veterinary old wives’ tale: one recent study has shown that when domesticated foxes were bred for friendliness, their coat color got mangier and uglier. Based on this study,7 many believe that coat color is associated with hormones that may make an animal nicer.
I personally believe that orange tabbies are the most outgoing, lovable of all the cat colors while the calico cats are the “queen” of the bunch (“Please don’t touch me. You’re disturbing me.”). If you really must know, calico cats often seem to be the meanest, most feisty cats while in the hospital. Don’t get me wrong – they may be wonderful angels at home, but they put up the worst fight at the veterinarian. Your veterinarian probably doesn’t tell you that once your female feline is at the vet clinic, she pretty much becomes, well, a vicious, drooling, ferocious tiger who’s trying to rip everyone’s eyes out (no, seriously). Whether or not it’s because she’s a female, or owing to the genetic link between friendliness and coat color, she’ll turn into a biting, scratching, screaming, vicious land shark when your veterinarian takes her into the back room. Most vet techs and vets have a healthy respect for these frenzied females. We’re talking drugs (chemical restraint), nets, leather gloves, muzzles, towels, fur flying, chasing, and so on. In fact, if you have a cat this color and know that she’s bad when you bring her to the vet, do us all a favor. Arrange to pick up oral sedatives first – it will make everyone’s life easier!
Color favoritism aside, veterinarians know that most orange and white tabbies are male, while most calicos and “torties” are female. Coat coloration is very complex as it is influenced by many genes and their genetic status as dominant or recessive (which is the strength in ability to be expressed). There are several alleles for each color (described as O for the orange allele (which is the dominant color gene, resulting in the orange color), or o for the black allele (which is the recessive color gene, resulting in non-orange fur). These colors are considered sex linked, as they are associated with the female X chromosome: the O gene is located on the X chromosome, and if you recall your tenth-grade science lessons about Mendel’s peas, you’ll recall the males are XY while females are XX. In other words, since males only carry one X chromosome, they are more likely to have orange fur since it’s also a dominant gene. Since o is recessive, it requires two oo to result in a non-orange color, while Oo yields the tortoiseshell color. To achieve the calico color, O and o both need to be expressed on the female X chromosome, and being that males only have one X chromosome, the majority of calicos are female (more than 90 percent). Voila! So, go ahead and skip eight years of veterinary schooling and sex your new kitten based on its colorings. If you just adopted a kitten, hedge your bets and pick out your favorite boy name for orange tabbies, and girl names for calico or tortie cats. If you ever see a male calico or tortoiseshell, you are (a) lucky or (b) the proud owner of a possible XXY animal, which you can name “Hermie.” (Congratulations, owning a hermaphrodite is quite rare!) While color coat expression is very complicated, know that orange tabbies are almost always male, while calico and torties are almost always female.
Photo from pasma on Flicker
Before we get into sex and genes and colors, know that some veterinarians are cat color biased. For years, veterinarians had mysteriously hypothesized that these color patterns were also linked to the friendliness gene. Interestingly enough, we may now have the scientific research to support this veterinary old wives’ tale: one recent study has shown that when domesticated foxes were bred for friendliness, their coat color got mangier and uglier. Based on this study,7 many believe that coat color is associated with hormones that may make an animal nicer.
I personally believe that orange tabbies are the most outgoing, lovable of all the cat colors while the calico cats are the “queen” of the bunch (“Please don’t touch me. You’re disturbing me.”). If you really must know, calico cats often seem to be the meanest, most feisty cats while in the hospital. Don’t get me wrong – they may be wonderful angels at home, but they put up the worst fight at the veterinarian. Your veterinarian probably doesn’t tell you that once your female feline is at the vet clinic, she pretty much becomes, well, a vicious, drooling, ferocious tiger who’s trying to rip everyone’s eyes out (no, seriously). Whether or not it’s because she’s a female, or owing to the genetic link between friendliness and coat color, she’ll turn into a biting, scratching, screaming, vicious land shark when your veterinarian takes her into the back room. Most vet techs and vets have a healthy respect for these frenzied females. We’re talking drugs (chemical restraint), nets, leather gloves, muzzles, towels, fur flying, chasing, and so on. In fact, if you have a cat this color and know that she’s bad when you bring her to the vet, do us all a favor. Arrange to pick up oral sedatives first – it will make everyone’s life easier!
Color favoritism aside, veterinarians know that most orange and white tabbies are male, while most calicos and “torties” are female. Coat coloration is very complex as it is influenced by many genes and their genetic status as dominant or recessive (which is the strength in ability to be expressed). There are several alleles for each color (described as O for the orange allele (which is the dominant color gene, resulting in the orange color), or o for the black allele (which is the recessive color gene, resulting in non-orange fur). These colors are considered sex linked, as they are associated with the female X chromosome: the O gene is located on the X chromosome, and if you recall your tenth-grade science lessons about Mendel’s peas, you’ll recall the males are XY while females are XX. In other words, since males only carry one X chromosome, they are more likely to have orange fur since it’s also a dominant gene. Since o is recessive, it requires two oo to result in a non-orange color, while Oo yields the tortoiseshell color. To achieve the calico color, O and o both need to be expressed on the female X chromosome, and being that males only have one X chromosome, the majority of calicos are female (more than 90 percent). Voila! So, go ahead and skip eight years of veterinary schooling and sex your new kitten based on its colorings. If you just adopted a kitten, hedge your bets and pick out your favorite boy name for orange tabbies, and girl names for calico or tortie cats. If you ever see a male calico or tortoiseshell, you are (a) lucky or (b) the proud owner of a possible XXY animal, which you can name “Hermie.” (Congratulations, owning a hermaphrodite is quite rare!) While color coat expression is very complicated, know that orange tabbies are almost always male, while calico and torties are almost always female.
Photo from pasma on Flicker
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