Question

In a particular species of frogs, black spots are a dominant trait and their absence is a recessive trait. In a population of frogs, 50 are homozygous for the dominant trait, 34 are heterozygous dominant, and 16 show the recessive trait. Which expression is the correct way to calculate the frequency of the dominant allele?

Answer 1

The allelic frequency is the frequency with which the allele of a variant in a population is found (expressed as percentage or portion). The sum of the allelic frequencies of all the alleles of a gene in a population is therefore by definition equal to 1. In population genetics, allelic frequencies represent the genetic diversity at the level of the population, or species.

To calculate it, it is considered that each frog has two alleles in its genome coding for black spots.

Allelic frequency = number of allele considered / total number of alleles = number of allele considered / total number of frogs * 2

Homozygous domianant means that it has two alleles for black spots, and heterozygous means that it has only one allele for black spot.

Allelic frequency of dominant allele = $\frac{50 * 2 + 37 * 1 }{(50 + 34 + 16) * 2}$ = 134/200 = 0.67.

Answer 2

The answer is C: 134/200