Imagine a mating between a non-ginger (n) queen and a ginger (g) tom.
The queen will always donate a non-ginger allele, and the tom will always donate a ginger allele, so the resulting female kittens will all have a genotype of ng and therefore be tortoiseshell. (And all the male kittens will be non-ginger, because their father has donated his Y chromosome and therefore they get their X chromosome from their mother, with her non-ginger allele).
Doing the maths, the only way to get a ginger female is by mating a tortoiseshell or ginger female with a ginger tom. In the former case 1/3 of the females will be ginger, and in the latter case all of them will.
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timeasmymeasure
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Date: 2010-12-15 10:08 am (UTC)Imagine a mating between a non-ginger (n) queen and a ginger (g) tom.
The queen will always donate a non-ginger allele, and the tom will always donate a ginger allele, so the resulting female kittens will all have a genotype of ng and therefore be tortoiseshell. (And all the male kittens will be non-ginger, because their father has donated his Y chromosome and therefore they get their X chromosome from their mother, with her non-ginger allele).
Doing the maths, the only way to get a ginger female is by mating a tortoiseshell or ginger female with a ginger tom. In the former case 1/3 of the females will be ginger, and in the latter case all of them will.
I think.