A storm washed five female and five male tiger beetles from the mainland to a small island that had no previous population of tiger beetles. In tiger beetles, having six spots is dominant to having four spots. All ten beetles had six spots, but one male and one female were heterozygous for the four-spot trait. If six of the beetles died randomly without reproducing, the ratio of the genotypes could be quite different in subsequent generations. This change in allele frequencies would result from which process?