Final answer:
Small populations are more susceptible to genetic drift and can experience a loss of genetic diversity if individuals die before reproducing. Large populations are less impacted by chance events due to a larger gene pool.
Step-by-step explanation:
Small populations are more susceptible to the forces of genetic drift. Genetic drift occurs because the alleles in an offspring generation are a random sample of the alleles in the parent generation. If one individual in a small population dies before it leaves any offspring, all of its genes will be suddenly lost, resulting in a loss of genetic diversity. In contrast, large populations are buffered against the effects of chance as the loss or addition of individuals has little impact on the total gene pool.