Imagine that one of the original four mice that escape from a research lab is blind due to a genetic defect. If the mice breed and most of the mice born in subsequent generations are blind from birth, this is most likely a case of:

The correct answer is founder effect.

Explanation:

A decline in the genetic variation, which arises when a small part of a large population gives rise to a novel colony is termed as the founder effect. This new population seems to be distinct from its original population, as it may possess different phenotypes and genotypes. However, in certain situations, the founder effect plays an essential role in the creation of novel species.  

Thus, the given case is a clear illustration of the founder effect, as the mouse that was blind from birth has resulted in the creation of separate generations of mice, which are blind from birth resulting due to a genetic defect. Therefore, a founder effect can at certain times influence a population in such a manner that they may prevail more of a specific kind of gene or less of a specific kind of gene.