Figure 1

Detection of sexual dimorphism in the abdominal musculature of D. melanogaster and some species of the montium group. Representative images (a1–a3,b1,b2,c1,c2,d1,d2) of abdominal muscles and the Gaussian fit to the F_A/F_B distribution of the largest muscle (a4,b3,c3,d3) in the reference species D. melanogaster (a) and 3 species of the montium groups, i.e., leontia (b), lactericornis (c) and cauverii (d). Images are typical examples of male abdominal musculatures with the exception of those for D. melanogaster, which are images of a wild-type male (a1), wild-type female (a2) and fru mutant male (a3). The MOL and its analogs are indicated with arrowheads, and the regions shown in Fig. 4 to visualize nuclei are boxed. D. cauverii is a species that did not show the neuromuscular sexual dimorphism in the A5 segment whereas 3 other species displayed the sexual dimorphism. Scale bar: 100 µm. The curves in a4, b3, c3 and d3 compare F_A/F_B distributions for the male A5 (red lines), the female (black lines) and male A4 (blue lines), and, only in a4, the male fru mutant A5 (magenta lines). The statistical differences were evaluated by the Brown-Forsythe and Welch ANOVA or Kruskal–Wallis test; ***P < 0.001.