In a population of 400 salamanders, some individuals have long toes and others have short toes. This phenotypic difference is due to a single gene with dominant and recessive alleles, T and t, where T confers long toes. If the toe length gene is in Hardy Weinberg equilibrium, and 256 individuals have short toes, how many individuals are heterozygous at the toe length locus?

Solution :

Total number of salamanders or population of salamanders is given = 400

Out of theses salamanders, some have long toes while others have a short toes.

Number of individuals of salamanders having short toes = 256

The short toe individuals

Therefore,

                    = 0.8

p + q = 1

∴ p = 1 - q

     = 1 - 0.8

     = 0.2

The number of the heterozygous individuals = (2pq x 400)

                                                                          =  ( 2 x 0.2 x 0.8 ) x 400

                                                                          = 0.32 x 400

                                                                          = 128