Question

Your family has recently acquired a 1000 cow herd comprised of Angus genetics. Unfortunately, the previous owners haven't kept very good records with regards to genetics, furthermore they haven't practiced any sort of artificial selection or culling for the past several years. Based on your knowledge of animal breeding you assume the population is in Hardy-Weinberg equilibrium. Upon seeing the herd for the first time your father is furious to see that there are 200 red cows in the population. You explain to him that coat color in Angus cattle is a completely dominant trait with black dominant to red. Based on this information, How many animals will display the BB, Bb, and bb genotypes? BB= 200; Bb = 500; bb = 300 BB= 200; Bb = 494; bb= 306 BB= 494; Bb = 306; bb= 200 BB= 306; Bb = 494; bb= 200

Answer 1

If 200 are red,

Frequency of Red genotype = bb cows is 200/1000 = 0.2 = bb = b².

Frequency of b allele = under root of b² = under root of 0.2 = 0.4472.

Now based on hardy weinberg equillibrium, B + b = 1.

so frequency of B allele = 1-b = 1-0.4472 = 0.5527.

The frequency of BB genotype = 0.5527² = 0.305,

So the number of BB or homozygous black cows = 305.

The rese are Bb = 495 cows.

So the correct answer should be:

Option D) BB = 306, Bb = 494, bb = 200

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