Question

In a population of tree frogs, the allele that causes yellow eyes (Y) is dominant over the allele that causes orange eyes (y). If 85% of frogs have yellow eyes, what is the frequency of the dominant allele?

Answer 1

Hardy-Weinberg Principle

Genotype frequency equation

 $p^{2} +2pq + q^{2} = 1$

Where p² is the freq of homo dominant genotype, 2pq is the freq of heterozygous genotype and q² is the freq of homo recessive genotype.

Allele frequency equation

p + q = 1

Where p is the frequency of dominant alleles and q is the frequency of recessive alleles.

Yellow eyes in the frog offspring is a phenotype (physical trait) that would be a expressed by a geneotype (YY or Yy). This frequency, 0.85 includes: p² + 2pq

0.85 + q² = 1

q² = 0.15

p = $\sqrt{0.15}$ 

Then p + $\sqrt{0.15}$  = 1

1 - $\sqrt{0.15}$ = p

p = 0.613

61%