Final answer:
Populations with reduced genetic diversity, such as those affected by population bottlenecks, are more susceptible to extinction because they have limited adaptability to environmental changes and increased risk of inbreeding.
Step-by-step explanation:
Populations with reduced genetic diversity, such as those that have undergone the bottleneck effect, face heightened risks of extinction. This is because when a natural disaster or other event causes a population bottleneck, it significantly decreases genetic variation within that population. When genetic drift occurs after such an event, the smaller genetic pool means that certain alleles, even harmful ones, can become more common in the population by chance.
Because genetic diversity is essential for a population's adaptability to changing environmental conditions and resistance to diseases, having a diminished gene pool reduces a population's ability to cope with these challenges. Moreover, with decreased variability, there is an increased risk of inbreeding, which can lead to inbreeding depression where the manifestation of harmful recessive alleles can increase due to related individuals reproducing. This can result in a reduced survival and reproduction rate for the population, rendering them more vulnerable to extinction.