Question

Which one of these is associated with multiple phenotypes?

• A. Mutation
• B. Pleiotropy
• C. Epistasis
• D. Polygenic inheritance

Answer 1

Answer: (D)

The phenotype of an individual depended on its genotype at all the relevant loci, with each allele adding a small amount. Traits that have this feature are called polygenic, ie, the genes, which are non-allelic and affect the phenotype of a single quantitative trait are called polygenes and their inheritance is called polygenic inheritance. This is proved by Nileson-Ehle in 1908 for kernel colour in wheat.
The term pleiotropy refers to the situation in which a gene influences more than one trait. The $H{b}_B^S$ allelic provides a classic example of pleiotropy.
In epistasis an allele of one gene obliterates the phenotypic expression of all allelic alternatives of another gene.