Final answer:
Genetic drift is the process that results in unpredictable changes in allele frequency due to random events and is most significant in small populations. It includes events such as the founder effect.
Step-by-step explanation:
The process where unpredictable changes in allele frequency occur in all finite-sized populations is known as genetic drift. This random fluctuation in allele frequencies is due to chance events, such as the mortality of individuals before they reproduce or the random selection of gametes during fertilization. Genetic drift is particularly influential in small populations, where the random loss or increase of alleles can have a substantial impact on the population's gene pool. A specific example of genetic drift is the founder effect, which describes how a new population started by a small number of individuals may have allele frequencies that differ from the original population due to chance alone.