Question

A person studies tweety birds that have a generation time of 1 year. He goes out and samples allelic variation at a gene that is on the Z chromosome (male birds are homogametic and have 2 copies of ZZ while females are heterogametic and have one copy of Z and one W). In his population, he notices that the frequency of a SNP in the gene he is studying is 75% in males and 25% in females.

How close to equilibrium frequency will males and females be at this locus by the time he graduates, 5 years later.

In a similar experiment, a woman sets up an experimental population with 500 individuals (flies) and plans to maintain the population at 500. She discovered a drug that prevents new mutations from arising. How long will it take for her population to reach half way to its equilibrium heterozygosity. How long will it take her to graduate? (note a fly generation time is 10 days)

mutation rate is not given

Answer 1

Ans. The allelic frquencies will remain same generation after generations according to hardy and weinberg prediction.Due to evolution number n will change as per generations i.e the genotypes frquencies will change with generations.SO assuming homozygotes and heterozygotes ZZ and ZW

gene frequency for ZZ = 75% = 0.75

gene frequency for ZW = 25%= 0.25

if we see the gametes Z,Z,W

probability that Z will cross Z( of female)=0.75*0.75=0.56

probability that Z will cross W(of female)=0.1875

The total genotype areZZ, ZW,ZW,ZZ

According to the equation p+q=1 and P² + Q² +2PQ=1

0.56+0.06+2pq=1

pq=0.30

This will remain same after 5 years.