Final answer:
Genetic diversity can be lost in a small population through the bottleneck effect caused by chance events or catastrophes, as well as through the founder effect when a portion of the population starts a new population or a physical barrier divides a population.
Step-by-step explanation:
Genetic diversity can be lost in a small population in several ways. One such way is through chance events or catastrophes, such as natural disasters, that reduce the genetic variability within the population.
This is known as the bottleneck effect. Another way is through the founder effect, which occurs when a portion of the population leaves to start a new population or when a physical barrier divides a population, resulting in a change in the genetic structure of the new population.