Final answer:
The population undergoing natural selection is not an assumption of populations exhibiting Hardy-Weinberg equilibrium for a given trait. The Hardy-Weinberg principle requires no natural selection, along with no mutations, random mating, no gene flow, and a very large population size to predict that allele frequencies will remain constant.
Step-by-step explanation:
The assumption of the Hardy-Weinberg equilibrium that is not a condition for populations exhibiting equilibrium for a given trait is 'e) The population is undergoing natural selection'. The Hardy-Weinberg principle states that in the absence of evolutionary forces such as mutation, gene flow (migration), genetic drift, and natural selection, the allelic and genotypic frequencies in a population will remain constant. Therefore, natural selection is indeed one of the mechanisms that can cause a population to deviate from Hardy-Weinberg equilibrium.
For a population to be in Hardy-Weinberg equilibrium, it must satisfy five conditions:
- No new mutations are occurring, so allele frequencies stay the same.
- There is no gene flow or migration into or out of the population.
- The population size is very large to minimize the effects of genetic drift.
- The population engages in random mating without mate choices based on genotype.
- There is no natural selection, so all individuals have an equal chance of survival and reproduction.
If any of these conditions are not met, the population is considered to be evolving, and the Hardy-Weinberg equations would no longer accurately predict allelic or genotypic frequencies in that population.