Problem 2 Danny Smokestack is a first year Ph.D. student in the Biology Departme

Question

Problem 2 Danny Smokestack is a first year Ph.D. student in the Biology Department at UVA. The Biology Department is very stringent and forces its students to graduate in exactly 5 years. His lab studies tweety birds that have a generation time of exactly 1 year. He goes out and samples allelic variation at a gene that is on the Z chromosome (note, in birds, males are the homogametic sex and have two copies of the Z chromosome [ZZ] and females are the heterogametic sex and have one copy of the Z and one copy of the W chromosome; this is the opposite of what happens in us, where males are XY and females are XX). In his population of tweety birds, he notices that the frequency of a SNP in the gene he is studying is at 75% in males and 25% in females. (10 pts) How close to equilibrium frequency will males and females be at this locus by the time Danny Smokestack graduates, 5 years later. Show your work

Explanation / Answer

2) According to population genettics:

For Males:

P2 = 75% = 0.86; but q=1-p = 0.14

P2 + 2pq + q2= 1 ; 2pq= 0.24

After 5 generations : p= 0.86 + (0.24/2)= 0.98; and q = 1-p = 0.02

Similarly for females : After 5 generations : p= 0.75 and q = 0.25

In Danielle's case for fruit flies:

Time required to go half way to equilibrium = T= 0.69314/ ; where = 10-5 = 69,300 generations

Generation time G= time per generation (t)/ no of generations (n) =

Given in question , a fly generation time = 10 days, sample size = 500

It will take her approximately 69,300 generations of flies to reach halfway equilibrium. That is aboubt 13 years.

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