When selective forces are absent or relatively weak, allele frequencies are equally likely to drift upward or downward at each successive generation because the alleles are subject to sampling error.
Rikala gaya selektif nénten wénten utawi ngendukang, frekuensi alel sareng-sareng pacang makeber ngaduurang utawi ngabeténang rikala soang-soang generasi sané ngantun santukan alel manut ring kaiwangan sikala ngambil sampel.