LATITUDINAL ADH ALLOZYMIC VARIATION AND ETHANOL TOLERANCE IN INDIAN POPULATIONS OF DROSOPHILA-MELANOGASTER

Ten Indian geographical populations of D. melanogaster were assayed el ectrophoretically for Adh genic variation. The Indian geographical pop ulations of D. melanogaster revealed significant clinal variation (3 % for 1 degrees latitude) at Adh locus and Adh(F) allelic frequency cor related significantly with increase in latitude. It was suggested that the abundance of secondary alcohols in the southern Indian tropical a nd humid environment might exert selective pressure favouring higher f requency of Adh(S) allele. Patterns of ethanol utilization as well as ethanol tolerance were analyzed in larval and adult individuals of six geographical populations of D. melanogaster. Latitudinal variation in ethanol tolerance was observed in D. melanogaster populations from In dia. The parallel occurrence of latitudinal variation of Adh locus as well as ethanol tolerance in Indian geographical populations of D. mel anogaster could be maintained by balancing natural selection varying s patially along the north-south axis of the Indian sub-content.