PHENOTYPIC PLASTICITY OF WINGS IN SELECTION LINES OF DROSOPHILA-MELANOGASTER

Plasticity in wing characters was investigated in lines selected for l ong and short wing length and for long and short thorax length in Dros ophila melanogaster. Selection lines were reared at 20 degrees C and a t 25 degrees C. All lines were raised across a temperature range from 17.5 degrees C to 27.5 degrees C after several generations of directio nal selection. We tested whether correlated responses in wing cell siz e and cell number and in plasticity occurred as a result of selection on wing size or thorax size. A difference in plasticity in the lines w as observed at different selection temperatures. Selection at 25 degre es C resulted only in a change in mean values, whereas selection at 20 degrees C led to some correlated responses in plasticity. Different r esults might have been obtained if more replicates of the selection li nes had been started from the same population. The results show that m ean size at a temperature and plasticity across temperatures are at le ast partly determined by different genes.