Phenotypic plasticity of wing size and shape in Drosophila melanogaster and D. simulans

Variation of 13 morphometric wing characters in relation to temperature of development was studied in two sibling species Drosophila melanogaster and D. simulans. Three principal components that accounted for 73% of variation of these characters were identified. The first component was interpreted as general wing size, while the second and third components described wing shape. Temperatures of maximal wing size and temperatures corresponding to the highest values of the third principal component (proximal-distal ratio) were different in the species studied. In each of the species, reaction norm curves of the three-principal components were different, indicating qualitative differences between reaction norms of characters belonging to the same organ. Variances of both general wing size and shape were different at different temperatures. Variance of general wing size was lower at intermediate temperatures and higher at high and low temperatures. Correlations between wing measurements were significantly different at different temperatures.