Twelve Indian natural populations of Z. indianus, collected along 22。 latitudinal range, were analysed electrophoretically for allozymic variation of seven gene-enzyme systems. Interestingly all the seven Est loci were found to be highly polymorphic in all the populations of Z. indianus. Except Mdh-2 all the fourteen loci revealed extensive polymorphism. The Indian continental populations of z. indianus revealed higher genetic similarities on the basis of Nei's genetic indices. The genetic structure of Z. indianus populations were characterised by significantly higher values of genetic indices as compared with other sympatric colonising Drosophila species from India; extensive inter-populational genotypic as well as allelic frequentcy heterogeneity; and higher genic differentiation at all the loci. All the polymorphic loci in geographical populations of Z. indiaus revealed latitudinal clines and changes in allelic frequencies were found to correlate with latitude. The patterns of genic differentiation in Z. indianus population were comparable to those of D. melanogaster populations from India and other continents. The occurrence of higher genetic variability in Z. indianus populations were in agreement with its habitat generalist or broad niche-width characteristics i.e. the species populations utilised diverse food resources and displayed adaptation to variable climatic conditions. Thus, the observed genic divergence patterns in colonising populations of Z. indianus could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian sub-continent.