In some traits, different phenotypes result from genes whose alleles each contribute a specific increment to the whole. The phenotypes then have a discontinuous phenotypic distribution. Group of answer choices: True False
The correct answer and explanation is:
The correct answer is False.
In genetics, when traits exhibit a discontinuous phenotypic distribution, this usually indicates that the trait is influenced by a small number of alleles, and each allele has a large, distinct effect. This is typically seen in traits governed by simple Mendelian inheritance, where the phenotypes fall into clearly defined categories (e.g., dominant and recessive traits). For example, eye color in humans, where a few specific alleles determine whether someone has blue or brown eyes, often shows a discontinuous distribution.
On the other hand, traits that show continuous variation (such as height or skin color) are typically influenced by multiple genes, each contributing a small, additive effect. These traits result in a continuous phenotypic distribution, where the range of possible phenotypes forms a spectrum. In this case, different alleles at various loci contribute small increments to the overall phenotype, and the trait does not exhibit distinct categories but rather a gradual range of variation.
For example, in human height, a large number of genes influence how tall a person becomes. Each gene contributes a small amount to the overall height, and there is no sharp boundary between “tall” and “short” individuals. Instead, the height distribution is continuous, with a range of heights observed in the population. Thus, traits with genes contributing increments to the phenotype are typically associated with continuous distributions, not discontinuous ones.