Is it known that three-haired cats are always females, the genes for black and red hair color are allelic? - briefly
Yes, it is known that three-haired cats are typically females due to X chromosome inactivation. Additionally, the genes for black and red hair colors in cats are indeed allelic, meaning they reside on the same locus.
Is it known that three-haired cats are always females, the genes for black and red hair color are allelic? - in detail
The assertion that all three-haired cats are female is not universally accurate. While it is true that male cats with a recessive X-linked genetic trait can exhibit this characteristic, it is more commonly observed in females due to their having two X chromosomes. This condition, known as X-linked hypotrichosis, results from a mutation on the X chromosome that affects hair growth. Since males have only one X chromosome, they are less likely to inherit this trait unless it is passed down from their mother. Therefore, while the majority of three-haired cats may be female, it is not an absolute rule.
Regarding the allelic relationship between the genes for black and red hair color in cats, it is important to note that these colors are determined by different genetic loci. The gene responsible for black fur is located on chromosome B (B for brown/black), while the gene governing red or orange fur is found on chromosome O (O for orange). These genes do not exhibit allelic relationships because they operate independently of each other in determining coat color. Therefore, the presence of one does not preclude the expression of the other; a cat can have a combination of black and red fur depending on its genetic makeup at these two distinct loci.