Abstract
The present study describes some polymorphic aberrations found in the salivary gland chromosomes of Drosophila immigrans which was based on three natural populations in Hokkaido.
The standard salivary gland chromosomes of D. immigransof Hokkaido are generally similar to those in Brazilian population according to the report of Freire-Maia et al. (1953).
In 384 larvae examined in this study, eight different types of chromosome aberrations (0.05 per larva) were observed in the second and the third chromosomes. The subterminal inversion in the right limb of the second chromosome was most frequent in occurrence (60.8per cent). There were two aberrations which were morphologically identical with those reported in Chiliean population by Brncic (1955).
In order to examine the frequency in occurrence of heterozygous inversions in the laboratory culture, brother-sister matings were carried out with a pair of flies with a subterminal inversion. The results showed that, during 10 mating generations, the ratio of the standard gene-arrangement to the heterozygous inversion was 1:1.
