When only a very few individuals give rise to a new population in a new area of favorable habitat, the new population might possess different genotype frequencies for a certain trait than the larger population from which it separated. This is called the effect.

Founder effect

Explanation:

The founder effect is the effect observed on the gene pool of a population when a non-random sample of a larger population gives rise to a new form of the population in a new habitat.

Since the new population is formed or founded by the non-random individuals of the larger population, therefore, the effect is called founder effect which is observed in terms of the gene pool.

Thus, the founder effect is the correct answer.

the animal that would be cutest if scaled down to the size of a cat? elephant