Question

) Imagine that you are a grad student in Biological Anthropology, and you travel to the land of “Jenesaiquoivia” to study Jenesaiquoivian genetics. [Footnote 1]

You notice that 9 out of every 100 people in your study group have blue eyes. The rest of the population have brown eyes. You know that the brown eyes allele is dominant, and blue eyes is recessive. [2]

Construct the Hardy-Weinberg equation for that population. You know that q²=.09 (9%) so p² plus 2pq must equal .91 (because (p²) + (2pq) + (q²) =1).

So (p²) + (2pq) + (.09) =1

a) What is the value of q? (Mind your decimal points!)   ________

(This will be equal to the square root of 0.09. You may use a calculator. Double check your answer.)

b) What is the value of p (=1-q)? ________

c) What percentage of the population are homozygous dominant (P²)? ________

d) What percentage are heterozygotes? ________

After a long and productive career in grad school, you return to Jenesaiquoivia as a young Ph.D. You again observe the frequency of blue eyes in your study group and find that it is now only 4 out of every 100 (4%). The gene pool has evolved.

a) What is the value of q? (Mind your decimal points!)   ________

b) What is the value of p (=1-q)? ________

c) What percentage of the population are homozygous dominant? ________

d) What percentage are heterozygotes? ________

In your discussions with your Jenesequoivian friends, you learn that just after your first visit, there was a migration of people into the region from the neighboring land of Noloséa. [3]

On the basis of this knowledge, to which of the mechanisms of evolution (mutation, selection, gene flow or drift) can you attribute the observed evolution of your study population? (A few words are sufficient; you don’t need to write a full sentence.)

(Terminology Note: “Pleiotropy” is a word we use for a single gene that has an effect on more than one trait. For example, leg length and total height are pleiotropically linked – tall people usually have longer legs, and long-legged people are usually tall. Cats with white fur and blue eyes are usually also partially or completely deaf. Deafness and color are pleiotropically linked in cats. Back in the “olden days,” we used to think “one gene = one trait,” but now we know that a single gene can have many effects. We call the multiple effects of a single gene “pleiotropies.”)

4) Many years have passed since your groundbreaking study of Jenaisequoivian genetics. Recently, gold was discovered in the neighboring Ichweissnochnicht Mountains, and many Jenesaiquoivians have emigrated to the gold fields.[4] You wonder if the genes for eye color might be "pleiotropically" linked to the genes for adventure.

You know that there has been no further immigration and no traits exist in Jeneaiquoivia that were not already there, so there have been no substantial mutations. Blue and brown eyes are equally effective at seeing, so no selection has been involved and drift is the major cause of change.

Analysis of the Jenaisequoivians now shows that 25% of the population has blue eyes.

Solve the Hardy Weinberg equation for this new generation.

Percent Homozygous Dominant: ___________

Percent Heterozygous: ___________

Percent Homozygous recessive: .25 (or 25%)

5) You know that selection, mutation, and drift are not causes of the change in frequency of blue eyes in Jenesaiquoivia from questions 1, 2, and 3 to Question 4 But the population of Jenesaisquavia now has a lot more blue-eyed people than it did in Questions 1 and 2. That means that people with one eye color are leaving Jeneaisaisquoivia more than people with the other eye color. What is the pleiotropic link between eye color and risk-taking behavior? (Which eye color “left home” more frequently?) (Again, a couple of words is sufficient for the answer.)

Answer 1

Ans(1):-

When 9 out of every 100 people in your study group have blue eyes. q²=.09 (9%)

(a) Value of q = 0.3

(b) Value of p = 1 - 0.3 = 0.7

(c) Percentage of homozygous dominant (p²) population = 0.7 x 0.7 x 100 = 49%

(d) Percentage of heterozygotes = (1 - 0.09 - 0.49) x 100 = 42%

Ans (2): When the frequency of blue eyes in your study group is 4 out of every 100 (4%).

(a) Value of q = 0.2

(b) Value of p = 0.8

(c) Percentage of homozygous dominant (p²) population = 0.8 x 0.8 x 100 = 64%

(d) Percentage of heterozygous = (1 - 0.04 - 0.64) x 100 = 32%

Ans(3): Migration corresponds to gene flow.

Ans(4) Percentage homozygous dominant (p²) = 0.5 x 0.5 x 100 = 25%

Percentage heterozygous (pq) = (1 - 0.25 - 0.25) x 100 = 50%

Percentage homozygous recessive (q²) = 25% (Given)

So, Hardy weinberg equation is (p² + 2pq + q² = 1) = (0.5)² + 0.5 + (0.5)² = 1

Ans(5): Brown eye colour is linked to gene of adventure or risk taking behaviour. Brown eye colour left home more frequently.