Consider a population of diploid organisms with genotypes A1

Consider a population of diploid organisms with genotypes A1A1, A1A2, and A2A2. A1A1 is lethal during embryonic development and A2A2 is fully viable but completely sterile.

What are the fitnesses of the 3 genotypes?

A1A1=    A1A2=    A2A2=

What is the equilibrium frequency of A1?    

What are the genotype frequencies found in the adults at equilibrium?

A1A1=    A1A2=    A2A2=

Solution

for two alleles A1 and A2: p+q=1
According to Hardy-Weinberg equation:
f(A1A1)=p²
f(A2A2)=q²
f(A1A2)=2pq

if the genotypes A1A1: A1A2: A2A2a have fitnesses 1-s : 1 : 1-t, then the equilibrium frequency of A1 is t/(s+t).
here , s=1 as A1A1 is lethal during embryonic development.
and , t=1 as A2A2 is viable but sterile.
hence fitness of A1A1=0
fitness of A1A2=1
fitness of A2A2=0
equilibrium frequency of A1=1/(1+1)=1/2=0.5=p
equilibrium frequency of A2=1-p=1=0.5=0.5=q

genotype frequencies found in the adults at equilibrium:
According to Hardy-Weinberg equation:
f(A1A1)=p2=(0.5)²=0.25
f(A2A2)=q2=(0.5)²=0.25
f(A1A2)=2pq= 2x0.5x0.5=0.5