Practice question

Genetic drift describes random fluctuation of allele frequencies due to sampling error of gametes each generation producing finite zygotes. Its magnitude scales inversely with effective population size Ne, variance approximating pq divided by two Ne. In large populations sampling error becomes negligible, frequencies remain stable, whereas small isolated populations experience pronounced drift leading to loss or fixation of alleles by chance alone. Bottlenecks and founder events intensify drift, eroding heterozygosity. Consequently small populations deviate rapidly from Hardy-Weinberg expectations and lose genetic variation over time.