Final answer:
Genetic drift is the random loss of alleles in a population, often having a substantial impact on small populations through chance events—such as natural disasters—that affect which alleles are passed to the next generation.
Step-by-step explanation:
The random loss of alleles in a population is known as genetic drift. This process occurs usually in small populations where allele frequencies can change dramatically due to random, chance events rather than by natural selection or mutation. These changes can occur because alleles in the offspring generation are a random sample of those in the parent generation, and not all may be passed on. An example of such an event that can result in genetic drift is a natural disaster, which may disproportionately affect certain alleles in a population.
Genetic drift can have a significant effect on a population's genome, especially in conjunction with other evolutionary forces such as mutation, gene flow, and natural selection. It's noteworthy that natural selection and genetic drift can occur simultaneously, and it's often difficult to pinpoint the precise cause of changes in allele frequencies. Moreover, specific instances like the founder effect can initiate an unexpected shift in allele frequencies within a particular segment of a population.