What is the likely nature of the allele responsible for the Manx cat phenotype?

The allele responsible for the Manx cat phenotype is likely to be classified as lethal. The Manx breed is characterized by a mutation that affects the spine of the cat, leading to a shortened or absent tail. This trait is associated with a dominant allele, but there is a critical aspect of its inheritance that designates it as lethal.

In Manx cats, the presence of two copies of the Manx allele results in embryonic lethality; kittens that inherit this allele from both parents typically do not survive. This means that while the trait can be manifested as a dominant phenotype in individuals that have one copy of the allele, the allele also has a lethal consequence when present in the homozygous form. Hence, this dual nature creates a specific pattern of inheritance that is not only dominant but significantly impacted by the lethal aspect when considering population dynamics and breeding.

In contrast, while recessive alleles can go undetected unless both copies are inherited, and multiple alleles introduce variation within a trait, they do not inherently encapsulate the lethal nature of the Manx allele. Therefore, labeling the Manx allele as lethal accurately reflects its impact on the phenotype and survival of the offspring.