Genetic and plastic effects for body melanisation in cold adapted - D. takahashii. Shama Singh. ZOOLOGY, UNIVERSITY OF DELHI, DELHI, India.

   Drosophila takahashii - exhibits broad variation for segmentwise melanisation resulting from genetic polymorphism and/or phenotypic plasticity. We analyzed segmentwise reaction norms for melanisation in D. takahashii. Wild individuals of D. takahashii were investigated for variation in frequency of body melanisation collected from highland localities of Indian subcontinent. Changes in melanisation of all segments showed higher effect of growth temperatures. Significant differences were observed between reaction norms (slope values) of melanisation in three anterior vs. posterior abdominal segments in this species. In the present study, first three abdominal segments showed continuous variation leading to plastic effects whereas, genetic polymorphism (heterozygote plastic effects) was observed for posterior abdominal segments (5th, 6th and 7th) due to variable dominance in 5th and 6th; and complete dominance in 7th segment. The present study has shown genetic variability as well plastic response for body melanisation in cold adapted- D. takahashii.