Final answer:
Small populations are significantly more susceptible to genetic drift, as each individual's genes constitute a larger proportion of the gene pool, leading to greater impact on the population's genetic diversity and increasing the risk of extinction.
Step-by-step explanation:
Genetic Drift and Population Size
Small populations are more vulnerable to genetic drift when compared to large populations. Genetic drift has a more pronounced effect on small populations because each individual represents a larger fraction of the total gene pool. For instance, if one individual in a population of ten fails to reproduce, 10% of the genetic diversity is lost. In contrast, losing one individual in a population of one hundred only affects 1% of the gene pool. This demonstrates that in small populations, random events can cause significant shifts in allele frequencies, potentially leading to reduced genetic diversity and increased chance of extinction.
Factors such as the founder effect and the bottleneck effect further underscore the impact of genetic drift on small populations. The founder effect occurs when a new colony is started by a few members of the original population, and the bottleneck effect takes place when a disaster drastically reduces a population's size, resulting in a loss of genetic variability. Both effects can lead to a population that carries a genetic structure vastly different from the original population, heightening the risks associated with genetic drift.