Multiple Alleles

What are Multiple Alleles? – Definition

In the case of multiple alleles, certain traits have more than two alleles that are found in a population. But each individual only has two alleles (if diploid), or only one (if haploid). There can be large number of possible allelic forms in that same population. This situation is called as multiple allelism.

The set of alleles is referred as multiple allelic series.

Features of Multiple Alleles

  • Multiple alleles always occupy the same locus on the chromosome.
  • Always influence the same character.
  • No crossing over among the member alleles of the same multiple allelic series.
  • Generally, wild type allele is dominant, mutant alleles may have dominant or intermediate effect.

Examples of Multiple Alleles

  • Coat color in mice.
  • Coat color in rabbit.
  • Eye color in Drosophila.
  • Blood group (ABO) in human.
  • Rh factor

Coat color in Mice

The coat or hair color in mice is determined by a single gene with a series of alleles. There are alleles for black, brown, agouti, gray, albino, and other colors of hair. These alleles follow order of dominance like agouti > black > albino. This means that agouti is dominant to black and albino; black is dominant to albino.