The following article is from the most recent National Geographic. We included i

Question

The following article is from the most recent National Geographic. We included it below for proof that genetics really does apply in the real world :)

As mentioned in the article, tribal legend in western Canada says that every tenth Black bear is actually white-colored. These white-colored bears are knows as "Spirit Bears" and are officially a sub-species of the American black bear species.

Researchers extracted DNA from hair samples, and found that out of 220 total bears, 22 are white. The white color is caused by a recessive gene.

Assuming Hardy-Weinberg equilibrium (random mating and a large enough population, and no mutation, migration, or drift), what is q = freq(white allele) for this population? (Enter in your answer as a decimal, rounded to the nearest hundredth place.)

What is p = freq(black allele)? (Again, enter your answer as a decimal, rounded to the nearest hundredth place.)

Out of these 220 American black bears sampled, how many would be expected to be black-colored, but carry a white allele? (Enter in your answer as a whole number.)

Let's say that 50 American black bears that are homozygous for the black color allele migrated from Alaska to western Canada and joined this population, increasing the total population from 220 to 270. This will change the allele frequencies in the population. After one generation of random mating, what proportion of bears in this new population would be expected to be black-colored, but carry a white allele? (Enter in your answer as a decimal, rounded to the nearest hundredth.)

Explanation / Answer

Ans) The frequency of white bear is q2 = 22 / 220 = 0.1

or q = 0.316 (Ans)

In Hardy Weinburg, we know "p+q =1 "

Therefore p = 1 - q

= 1 - 0.316 = 0.684 (Ans)

Expected to be black colour carrying white allele i.e. heterozygous = 2pq X 220

= 2 X 0.684 X 0.316 X 220 = 95.10 = 95 {Ans}

After the migration the expected number of heterozygous = 2 X 0.684 X 0.316 X 270 = 116.71 = 117 (approx.) {Ans}

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