Final answer:
The bottleneck effect reduces genetic diversity in a population and can lead to the elimination of certain alleles due to events like natural disasters, which cause a drastic reduction in population size.
Step-by-step explanation:
The bottleneck effect is an extreme form of genetic drift that acts to reduce genetic diversity in a population. It can lead to elimination of one or more alleles. When a natural disaster, such as a wildfire or hurricane, randomly kills a large portion of the population, the few survivors' genetic makeup suddenly becomes the new genetic structure of the entire population. This reduced population is likely to have different allele frequencies compared to the original population before the disaster. As a result, the genetic diversity is greatly decreased, potentially leading to a loss in genetic variation which is essential for a population's ability to adapt to new environmental challenges.