Strains May Differ in Allele Kinds.

Consider a trait such as chin whisker hairs in the fictional organism the New Jersey Rumbunny.    As previously, discussed, Pine Barrens and Carteret Rumbunnies have at least 20 chin whiskers (due to genes which are not segregating in these strains). The number of additional whiskers is controlled by genotype according to the following rules.

A₁ allele adds 4 chin whiskers; A₂ allele adds 0 chin whiskers

B₁ allele add adds 2 chin whiskers; B₂ allele adds 0 chin whiskers.

Further investigation demonstrated that the two strains of rumbunnies approximated Hardy-Weinberg equilibrium for chin whiskers.

Scientist study the Delaware Water Gap rumbunnies and discover that they possess a third allele of the chin whisker gene A₃.  This allele also acts additively and adds 3 chin whiskers.  The mean number of chin whiskers of 2100 rumbunnies from the Delaware Water Gap Population is 28

The gene frequencies in the three populations were as follows:

Thus the expected distribution of chin whiskers by genotype in the three populations is:

 The water Gap populations from the other two populations not only in the gene frequencies of the A₁ and A₂ alleles but also because it has an additional allele A₃.  Finding the number and nature of the genes between Pine Barrens and Carteret Rumbunnies only partially explained the phenotypes seen in the Water Gap Rumbunnies. 

See Strains may differ in the genes segregating.