Question

in a large, randomly mating population, the frequency of an autosomal recessive lethal allele is 0.20. what will the frequency of this allele be in the next generation if all homozygotes die before reproducing?

Answer 1

The frequency of a recessive lethal allele in a large, randomly mating population where homozygotes die before reproducing will remain the same in the next generation. The surviving offspring's genotypes are either AA or Aa since aa individuals die, so the allele frequency stays at 0.20.

Step-by-step explanation:

In a large, randomly mating population with a frequency of an autosomal recessive lethal allele of 0.20, and assuming that all homozygotes die before reproducing, we can predict the frequency of this allele in the next generation. In this scenario, only the wild-type homozygotes (AA) and heterozygotes (Aa) will survive to reproduce. When two heterozygous individuals (Aa) mate, the expected genotypic ratio in their offspring would be 1:2:1 under normal Mendelian inheritance for a single-gene trait with two alleles. However, because aa individuals die before reproducing, the actual observed ratio is 1:2:0.

This pattern of inheritance is referred to as recessive lethal. The recessive allele is lethal in the homozygous form (aa), leading to only three possible genotypes among the surviving offspring: AA and Aa. As a result, half of the surviving offspring will be heterozygous carriers of the allele. The allele frequency remains the same because carriers (Aa) still possess the lethal allele, and it can be passed on to the next generation with the same probability as before. Hence, the frequency of the recessive lethal allele in the next generation will remain at 0.20, assuming there is no other evolutionary force acting on the allele frequency like mutation, migration, or selection for or against heterozygotes.

Answer 2

In a large, randomly mating population, the frequency of an autosomal recessive lethal allele will be 0.80 in the next generation if all homozygotes die before reproducing.

Step-by-step explanation:

In a large, randomly mating population, the frequency of an autosomal recessive lethal allele is 0.20. If all homozygotes die before reproducing, the frequency of this allele in the next generation will be reduced. To calculate the new frequency, we need to consider the Hardy-Weinberg equation, which states that p² + 2pq + q² = 1, where p is the frequency of the dominant allele and q is the frequency of the recessive allele. In this case, the frequency of the recessive allele (q) is given as 0.20, so we can solve for p. Rearranging the equation gives us p = 1 - q, so p = 1 - 0.20 = 0.80. Therefore, the frequency of the dominant allele will be 0.80 in the next generation.