In unicorns, three alleles at a gene determine the condition of the horn. The allele for a twisted horn, HT, and the allele for a long horn, HL, are codominant; both are completely dominant to the hornless allele, h. The frequency of hornless individuals in the population is 16%, and the frequency of the allele for twisted horns is 0.1. What is the frequency of the long horn allele?

According to the given information, the frequency of the hornless genotype in the population is = 16% = 0.16. This means that the frequency of the hornless allele in the population is = square root of 0.16 = 0.4.

The gene for the horns in unicorn has three alleles. If the frequency of the allele for twisted horns is represented by "p" and that of the hornless allele is represented as "q", then the frequency of the allele for the longhorn would be (r) = 1- (p+q).

This is due to the fact that the sum total of frequencies of all the possible alleles of a particular gene in a population in the Hardy Weinberg Equilibrium is always 1 (p+q+r =1). Now, putting the values of p and q in the formula to calculate the frequency of allele for the longhorn (r) = 1- (0.1 + 0.4) = 1-0.5 = 0.5