Use this information to answer the following question. A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait (aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants. What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait (aa) has not changed over time?

Answer: no mutation, no selection, no migration, a large random mating population.

Explanation:According to hardy-weinberg In a large random mating population in the absence of migration, mutation and selection gene and genotype frequency is at equilibrium.

For the reccesive gene frequency to remain contact some factors have played a major role in maintaining the equilibrium this include;

1. A large random mating population - Mating is random (individual is having equal chance of being mated too) among this population and the population been large prevent genetic drift of some genes that are few which is common in a small population. Genetic drift lead to loss of some genes.

2. No mutation - Mutation is a sudden heritable change that affects equilibrium. Its absence will prevent change in gene frequency.

3. No migration - Is the movement in and out of a population that could alter or change gene frequency.

4. Selection alters gene frequency and its said to be the greatest force.

If all these factors are in place in right proportion alterations of he frequency will not be possible.