The Hardy-Weinberg equilibrium represents an idealized, evolution-free population in which the allele frequencies and genotype frequencies will not change over time. In order for this to happen, five conditions must be met: 1) there must be no mutation; 2) there must be no gene flow between populations; 3) the populations must be very large; 4) all mating must be random; and 5) there must be no natural selection. If one of these five conditions was violated, genetic change, and thus evolution, would occur in the populations of subsequent generations. Suppose that only condition 3 were violated—that the population was very small. In this situation, the evolution would probably be due to _________.