Fig. 3: Morphological features of the projection neurons innervating a given glomerulus in different Drosophila species.

a Schematic depicting the technique used to photo-label the projection neurons innervating a given glomerulus: a glomerulus is used as a landmark for photo-labeling (blue dashed outline), and the projection neurons connected to the targeted glomerulus are photo-labeled after successive rounds of photo-labeling. b The projection neurons innervating the DL2d (upper panels), DC3 (middle panels) and VM5v (lower panels) glomeruli were photo-labeled in D. melanogaster (left column of each panel), D. simulans (middle column of each panel) and D. sechellia (right column of each panel); the cell bodies of these neurons (left panels) and the axonal termini that these neurons extend in the mushroom body (right panels) were imaged. Scale bar is 50 µm. c, d The number of photo-labeled neurons (c) and the volume of the presynaptic boutons these neurons form in the mushroom body (d) were quantified and compared across species (red: D. melanogaster; blue: D. simulans; green: D. sechellia). The statistical significance, or p-value, was measured using the Mann–Whitney U test (*p-value < 0.5, **p-value < 0.01, ***p-value < 0.001; n = 5, standard deviation from mean is shown). See Table 1 for quantifications. All source data used in this figure are provided in the Source Data file.