Question

A population of 100,000 Arabidopsis thaliana plants is initially at Hardy-Weinberg equilibrium for the A gene, where two alleles, A1 and A2, are present at equal frequencies. The population undergoes 2 generations of 100% self-fertilization. a) After 2 generations of selfing, what are the expected values for: 1) genotype frequencies, 2) allele frequencies, and 3) the population inbreeding coefficient. (The math is easiest using fractions.)

Answer 1

The population is at Hardy-Weinberg equilibrium for A gene.Where two alleles A1(p) and A2(q) are present at equal frequencies.

Hence p+q = 1
where, p= 0.5 and q= 0.5

Now Hardy-Weinberg principle states that the genetic variation will remain unaltered in absence of disturbing factors (mutation, migration, selection).

So,
2) Allele frequencies after 2 generation of selfing will be

p= 0.5
q= 0.5

1) The frequency of heterozygotes would be halved every generation.

Generation 1:
pp = 1/4
2pq= 1/2
qq = 1/4

Generation 2:

pp = 3/8
2pq= 1/2*1/2 =1/4
qq = 3/8

3) inbreeding coefficient:

Observed heterozygosity not known.