In the given scenario, the allele B for a black coat is dominant, and the allele b for a spotted coat is recessive.
A dog will have a spotted phenotype if it has the genotype that includes two recessive alleles. This means that only the bb genotype will result in a spotted coat.
The other genotypes would produce different phenotypes:
- BB would result in a black coat.
- Bb would also result in a black coat because the dominant allele B will express itself.
Therefore, the genotype that leads to a spotted phenotype in this dog breed is bb.