Orange color in non-pedigreed cats is controlled by the O locus. The non-orange phenotype, if not diluted,
appears as black coat color. Perform the following reciprocal crosses:
Orange blotched female X black blotched male
Black blotched female X orange blotched male
What conclusions can be drawn regarding the inheritance mechanism of the O locus?
To understand the inheritance mechanism of the O locus in non-pedigreed cats, we need to analyze the results of the reciprocal crosses.
Reciprocal crosses involve swapping the gender of the parents in a breeding experiment. In this case, we have two crosses:
1. Orange blotched female X black blotched male
2. Black blotched female X orange blotched male
Let's examine the outcomes of each cross:
1. Orange blotched female X black blotched male
In this cross, the orange blotched female is homozygous (OO) for the O locus, and the black blotched male is homozygous (oo) for the non-orange phenotype. The female contributes one O allele, and the male contributes one o allele to the offspring. All the offspring will be heterozygous (Oo) for the O locus. Therefore, all the offspring should be orange blotched.
2. Black blotched female X orange blotched male
In this cross, the black blotched female is homozygous (oo) for the non-orange phenotype, and the orange blotched male is heterozygous (Oo) for the O locus. The female contributes one o allele, and the male can contribute either an O or o allele to the offspring. The possible genotypes of the offspring could be Oo or oo. Therefore, half of the offspring should be orange blotched, and the other half should be black blotched.
From the results of these reciprocal crosses, we can conclude that the inheritance of the O locus in non-pedigreed cats follows a simple dominant-recessive pattern. The presence of at least one O allele (heterozygous or homozygous) will result in the orange blotched phenotype, while the absence of O alleles (homozygous for o) results in the black blotched phenotype.