3/14/2024 0 Comments Cat tortoiseshell vs calicoSince each cell can only activate one X at a time, this is what produces a random pattern of oranges and blacks across the cat’s fur. Goofy photo of my tortoiseshell calico (Zoey) and her many toes. If the kitten gets a gray X, they will have a gray base coat. If one of her kittens gets a black X, then they will have a black base coat. The gray X represents a black gene that is being influenced by another gene. For simplicity in the illustrated diagram below, mom has both a black X and a gray X. If you start with black paint (black gene) and mix in a little white (such as the white piebald gene), you will get gray. You can think about how these other genes influence coat color much like mixing paints. In the case of mama kitty and her gray son, they inherited a black X and a shade-influencing gene on another chromosome. Since this gene is not located on the sex chromosomes, all sexes can have white fur! It causes the fur to lose its pigment or color. This gene causes a condition called “ piebalding” which is similar to albinism. For example, the gene that controls white coloring, or rather the lack of color, is not located on the X chromosome. You may be asking, if mom only had black color genes on her Xs, why is she and one of her male offspring gray? Shouldn’t they all be black? While the genes for orange and black coat color lie on the X chromosome, there are “influencer” genes on other chromosomes that can modify the shade of coat color. Zoey and her sister on the other hand, inherited both a black X from mom and an orange X from dad. The boys inherited one X chromosome from mom and one Y chromosome from dad therefore, they were only given one gene for coat color, which was black. Illustration of the X chromosome containing a single gene for coat color encoded by DNA. When her mom gave birth, she had one solid gray boy, one solid black boy, and two tortoiseshell girls (see illustrated diagram of their family tree). She received one X chromosome from each parent – one X from gray mom and one X from orange dad. Zoey’s mom was solid gray and her dad was an orange tabby. My cat Zoey is actually a good example of how the genetics of calicos/torties work. Since all females are XX and males are XY, that leaves females with twice the number of coat color genes compared to males. This gene for coat color is located on the X chromosome. In cats, the gene (portion of DNA) that determines coat color comes in two forms (called alleles): orange or black. Males are born with one X chromosome and one Y chromosome (XY), while females are born with two X chromosomes (XX). Chromosomes are thread-like structures of DNA located within the cells that make up our bodies. Genetics also determine our biological or assigned-at-birth sex, specifically our X and Y chromosomes (in mammals). DNA determines why we are born with black hair or blonde hair, or with brown eyes or green eyes. DNA is the blueprint for all living things, including you, me, and our furry whiskered companions. The answer lies in their genetics or DNA. The reason why all calico cats are female is the same for tortoiseshell cats. Photo of my tortoiseshell calico cat, Zoey. My cat, Zoey, is considered a “dilute tortoiseshell” because the black, white, and orange in her fur are less vibrant, giving a coat that is more gray overall. Calicos and torties (as tortoiseshells are often called) can also come in a variety of shades. Similar to how all squares are rectangles (have four sides), but not all rectangles are squares (all sides of the same length). While all calico cats are tortoiseshell, not all tortoiseshell cats are calicos. Tortoiseshells often also have smaller speckles of color rather than the large quilt-like patches on calicos. Tortoiseshell cats are similar to calicos, but can have two (orange and black) or three colors (orange, black, and white) in their coat (see above illustration). All calicos have at least three colors of fur. While the pattern and shade of these classic Neapolitan kitties can vary widely, there is something they all share in common: all calico cats are female!Ĭalico is not a breed of cat, but rather a name for a particular tri-color coat pattern. Coat differences between calico (large splotches of 3 colors) and tortoiseshell (smaller splotches of 2-3 colors). Image is author’s own work.Ĭalico cats have a secret hidden under all those cute black, white, and orange spots.
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