Respuesta :
Perhaps the habitat has changed, for example, dried up, so not much green vegetation. The green beetles are thus more vulnerable, favouring the brown ones. With less green beetles to take part in mating, relatively more g alleles are present, to the point that they become the majority.
Answer:
Beetles with the brown allele immigrated into the population; the beetles mated and reproduced, incorporating the recessive allele into the gene pool.
We know nothing about the habitat; we only know about the alleles. It would make the most sense to infer that gene flow through immigration occurred to change the allelic frequency.