a, Three-dimensional surface renderings of typical fly brains from wild type Canton S (a1) and FoxP³⁹⁵⁵ mutants (a2). PLOS ONE can only handle 3D PDF figures as part of the supplementary files. Hence, the 3D functionality for Figure 6 is available as Figure S3. Alternatively, a fully functional PDF will be hosted on BBs website.

b, Quantitative volumetric analysis of eleven major neuropils (M – medulla, L – lobula, LP – lobula plate, MB – mushroom bodies, AL – antennal lobes, FB – fan-shaped body, OT – optic tubercle, EB – ellipsoid body, OG – optic glomeruli (purple in a), PB – protocerebral bridge, N – noduli) revealed a significant reduction in the volume of the optic glomeruli in FoxP³⁹⁵⁵ flies (Mann-Whitney U-Test, U = 2.0, p<0.002). The volume of the remaining neuropils (denoted PL – protocerebral lobes) did not differ significantly. Asterisk – significant difference with a Bonferroni-corrected level of p<0.004. Black stripes – median, boxes – 25–75% percentiles, whiskers – total range. Grey boxes indicate FoxP³⁹⁵⁵, white boxes Canton S.

c, Principal Components Analysis of the volumetric data. Plotted are the factor loadings of the individual flies on the two first components. Colored bars indicate means and standard errors (PC). Factor loadings are significantly different between Canton S and Foxp³⁹⁵⁵ for PC1 (Mann-Whitney U-Test, U = 52.0, p<0.04), but fail to reach significance for PC2. Number of brains analyzed: 7 (Canton S) and 9 (Foxp³⁹⁵⁵).