Final answer:
The characteristic that is NOT true for an ideal Hardy-Weinberg population is any evolutionary force like natural selection or genetic drift, as these factors cause changes in allele frequencies and lead to evolution.
Step-by-step explanation:
Characteristics of an Ideal Hardy-Weinberg Population
The Hardy-Weinberg law is based on the principle that allele and genotype frequencies remain constant in an ideal population if certain conditions are met. The conditions for a population to be in Hardy-Weinberg equilibrium include no mutation, no migration (gene flow), a very large population size, random mating, and no natural selection. If one of these factors is not present, the population may not be in equilibrium. Therefore, the characteristic that is NOT true for an ideal Hardy-Weinberg population would be any factor that introduces change in allele frequencies such as natural selection, as it directly influences the genetic makeup of the population, causing it to evolve.
In summary, the key conditions for Hardy-Weinberg equilibrium are no evolution forces acting on the population. Hence, any characteristic that describes an evolutionary force like natural selection or genetic drift will not be a characteristic of an ideal population based on the Hardy-Weinberg principle.