Integration of the Gene Pool as Demonstrated by Resistance to DDT

Crosses between resistant lines of D. melanogaster, developed independently by the same method of selection over some twenty generations, give an F1 population of the same resistance as the parent lines and an F2 with significantly lower resistance and a mortality distribution of greater variance. These phenomena indicate that the two lines have achieved resistance by consolidating different combinations of factors for resistance. The significance of this finding is discussed in the light of other recent evidence that the gene pool of a population is an integrated whole.