Final answer:
Genetic drift is a process where allele frequencies in a population change due to random chance events. It can have a major impact in small populations and differs from natural selection. The founder effect is a specific type of genetic drift.
Step-by-step explanation:
The evolutionary process being described is genetic drift, which is a change in the relative frequency of alleles in a population due to random or chance events. Genetic drift can cause significant changes in a population's genome, especially in small populations, because alleles may not be passed to the next generation simply due to chance events such as mortality, mating failures, or the random combination of gametes.
In contrast to genetic drift, natural selection leads to allele frequency changes based on the advantage certain traits provide for survival and reproduction. The founder effect is a kind of genetic drift that occurs when a new colony is started by a few members of the original population, leading to a significant shift in the allele frequencies that may not represent the original population.