GENETIC-BASIS OF SOME MORPHOLOGICAL DIFFERENCES BETWEEN TEMPERATE ANDEQUATORIAL POPULATIONS OF DROSOPHILA-MELANOGASTER

The genetic basis of three morphological traits (ovariole number, ster nopleural bristle number and wing length) of Drosophila melanogaster h as been investigated in natural populations that show great difference s in these traits, i.e. Bordeaux (France) and Loua (Congo). F1 and F2 crosses, and chromosome substitutions between these two populations, w ere analysed. Maternal and/or X chromosome effects were found for ster nopleural bristle number and wing length. For all traits, significant effects from each of the three chromosomes were found, but in general only one or two chromosomes had a major effect. Moreover, in all cases significant interactions between chromosomes were observed, suggestin g the existence of epistatic effects. Our results are discussed and co mpared to those obtained from the analysis of selected laboratory stra ins.