One population of a species has 25 individuals, all with genotype AA; a second population of this species has 40 individuals, all with genotype aa. Assume that these populations live far apart but in similar environmental conditions. Based on this information, the observed genetic variation most likely resulted from ________.
A) genetic drift
B) gene flow
C) nonrandom mating
D) directional selection

Question

Quizplus · Accepted Answer

Genetic drift is a mechanism of evolution that leads to a change in the gene frequencies of a population due to random sampling of organisms. The scenario described, where two populations of the same species have fixed but different genotypes (AA and aa) despite living in similar environmental conditions, suggests that chance events have led to the fixation of these alleles rather than selection, mating patterns, or gene flow influencing these outcomes. Gene flow, nonrandom mating, and directional selection would not typically result in such distinct genetic uniformity within separate populations without the influence of other factors.

One Population of a Species Has 25 Individuals, All with Genotype