DIFFERENCES IN GENE ACTIVITY IN A DROSOPHILA SPECIES CLUSTER BELONGING TO THE OBSCURA GROUP

The polytene chromosome puffing pattern of Drosophila madeirensis was established and compared with those of the related species D. subobscu ra and D. guanche. A total of 145 loci, active in some of the 12 devel opmental stages analysed, were described, 38 of which were found to fo rm the puffing pattern characteristic to this species. Taking into acc ount the number of puffs as well as the mean puff expression, D. madei rensis shows a similar activity level to 1). guanche, both species bei ng less active than D. subobscura. The low gene activity of D. madeire nsis and D. guanche was explained as a consequence of their ecological characteristics.