Random Genetic Drift in a Small Population

Genetic drift in a small population can easily drive certain alleles extinct, even though they had no negative effect on survival. In small populations, random genetic drift can also do the inverse. It can take an allele and make it the only version of that gene left in thePopulation genetics term for when anallele becomes present in the entire population is fixation. For a closed population, once a gene variant is fixed, they're stuck with it.