Ablack dog is bred with a brown dog, and all the puppies have patches of black and brown. the color coat alleles for black and brown are an example of

Codominance

Explanation:

Codominance is a genetic situation in which the two alleles representing a particular gene exert equal effects on each other when in heterozygous condition. Both alleles are phenotypically expressed  in the heterozygous organism.

In this case, the black and brown coat color were expressed in the resulting offspring of the cross, a clear indication of codominance.

it is called the mitotic spindle