Question

In a population of anteaters in South Africa, T₁ and T₂ are autosomal, incompletely dominant alleles that control tongue length. The alleles are polymorphic in this population, with f(T₁) = 0.95 and f(T₂) = 0.05. Anteaters that have long tongues are T₁T₁, T₁T₂ individuals have medium-length tongues, and T₂T₂ individuals have short tongues. A disease that wipes out the ants with deep nests occurs in this ecosystem, exerting strong natural selection on the long-tongued anteaters (they are ineffective at eating ants from shallow nests). As a result, 100% of the short-tongued anteaters survive this change in food supply, 40% of the medium-tongued anteaters survive, and 10% of the long-tongued anteaters survive.

A) Assuming the population begins in Hardy-Weinberg equilibrium and consists of 1,000 individuals, how many long-, medium-, and short-tongued individuals would you expect to be present in the original population (before selection)?

B) Assuming the population begins in Hardy-Weinberg equilibrium, what are the allele frequencies after one round (the initial round) of natural selection?

C) Assuming random mating takes places among the survivors of this first round of selection, what are the genotype frequencies of their offspring (the second generation)?

D) The deep-nesting ants have gone extinct and tongue length remains a trait under selection in the second generation of anteaters as in the initial population (i.e., same proportion of survivors). What are the allele frequencies in the surviving population of the second generation of anteaters when they begin to mate?

Answer 1