Answer and Explanation:
In the case described, where genotype frequencies change from generation 1 to generation 2 but return to the original frequencies in generation 3, the genotype frequencies are in a stable equilibrium.
Hardy-Weinberg equilibrium is a principle in population genetics that describes the relationship between allele and genotype frequencies in a population when certain conditions are met. In a stable equilibrium, the genotype frequencies remain constant over generations as long as the conditions for Hardy-Weinberg equilibrium are maintained.
The conditions for Hardy-Weinberg equilibrium include a large population size, random mating, no migration, no mutation, and no natural selection. When these conditions are met, the allele and genotype frequencies in a population will remain stable over time.
In the scenario described, the genotype frequencies initially change from generation 1 to generation 2, but they eventually return to the original frequencies in generation 3. This suggests that the population is experiencing temporary deviations from Hardy-Weinberg equilibrium, possibly due to random chance or other factors. However, since the genotype frequencies return to the original frequencies, it indicates that the population is still in a stable equilibrium.
Overall, when genotype frequencies remain stable over multiple generations, even if there are temporary deviations, it indicates a stable equilibrium in accordance with the Hardy-Weinberg principle.