Crossing true breeding dark-coated sheep with true breeding light-coated sheep always results in 100% dark-coated offspring. You are screening a population of Soay sheep for coat color, and you count 368 dark sheep and 132 light sheep. Assuming that this population is in Hardy-Weinberg equilibrium, what is the genotype frequency (not allele frequency) of the homozygous recessive sheep for TYRP1 gene

The correct answer is : 0.264

Explanation:

The total population of the Soay sheep is : 368 dark sheep + 132 light sheep

          = 500 sheep.

Total dark coat sheep ( dark allele represented by D as it is dominant) = 368

Total light coat sheep ( light allele represented by d as it is recessive) = 132

As we know crossing is took place in between true breeding:

           DD × dd

F1,           Dd        ( all are dark coat)

So, the genotype frequency of the homozygous recessive allele is

       = 132/500               (by Hardy - Weinberg equation)

       = 0.264

Thus, the correct answer is 0.264.