GENETIC VARIABILITIES IN SECOND AND THIRD CHROMOSOMES FROM KOREAN POPULATIONS OF <i>DROSOPHILA MELANOGASTER</i>

Abstract

1. Three samples of Korean Drosophila melanogaster from two localities were analyzed for viability factors and specific visible mutations in 474 second and 539 third chromosomes by the use of Cy and TM3, Ser balancer stocks, respectively. Lethals were tested for their allelism in both autosomes.2. The combined frequencies of lethals and semilethals ranged 13.0 to 16.1% among second and 16.3 to 20.0% among third chromosomes, but with no significant differences between collections for each autosome.3. The two autosomes differed significantly in three viability categories (incidence in lethals, subvitals supervitals) of the five, considered when chromosomes II and III data are combined. The meaning of the higher incidence of lethals in the third chromosome is not clear.4. Lethal allelism rates were similar among both autosomes in both intra- and inter-population tests. There was a similar allelism rate for the totals of chromosome II vs. III, although the rate differed significantly from population to population. The intra population allelism rates for ohromosomes II+III ranged from 0.6 to 2.6%.5. In S62, lethal concentration was preserved at fairly constant level around 16% during a season, while both it's breeding size and it's allelism underwent fluctuations.6. The estimated effective number of breeding individuals are about 2400 in S62g, 17500 in S62j and 3400 in K62i. These figures apparently indicate that the present populations are much larger than that studied in 1957-1958 in the southern part of Korea, but are much smaller than those in the American and Mediterranian populations.7. The recessive visibles, bw or or and p, are found to be common in the present populations. The distribution of these visibles in the three populations was random.8. Two “Cy-lethals” were also detected in S62j.