Clade: Phylogenetic clade to which each indivdual belonged (Oleriina, Napeogenes, Hypothyris), as used in our analyses Genus: The genus to which each individual belonged Species: The species to which each individual belonged Mimicry: The colour pattern of each species, categorised as either 'Colour' or 'Transparent' as used in our analyses Flight height: the mean flight height of each species, obtained from Elias et al. (2008) Sex: The biological sex of each individual (male/female) Year: The year in which each sample was collected ID: The unique numerical ID of each species Me_raw: The raw volume of the medulla, obtained using the 'measure statistics' module in Amira Lop_raw: The raw volume of the lobula plate, obtained using the 'measure statistics' module in Amira Lob_raw: The raw volume of the lobula, obtained using the 'measure statistics' module in Amira Al_raw: The raw volume of the antennal lobe, obtained using the 'measure statistics' module in Amira AOTu_raw: The raw volume of the anterior optic tubercle, obtained using the 'measure statistics' module in Amira aMe_raw: The raw volume of the accessory medulla, obtained using the 'measure statistics' module in Amira vLobl_raw: The raw volume of the ventral lobula, obtained using the 'measure statistics' module in Amira OL_raw: The raw volume of the optic lobe, obtained by summing the raw volumes of the medulla, lobula plate, lobula, accessory medulla and ventral lobula Central_brain_raw: The raw volume of the central brain, obtained using the 'measure statistics' module in Amira rCBR_raw: The raw volume of the 'rest of central brain', obtained by subtracting the raw antennal lobe and anterior optic tubercle volume from the raw volume of the central brain. rCBR: The log-10 transformed volume for the rest of central brain ME: the log-10 transformed volume for the medulla LOP: the log-10 transformed volume for the lobula plate LOB: the log-10 transformed volume for the lobula AL: the log-10 transformed volume for the antennal lobe AOTU: the log-10 transformed volume for the anterior optic tubercle aME: the log-10 transformed volume for the accessory medulla vLOB: the log-10 transformed volume for the ventral lobula OL: the log-10 transformed volume for the optic lobe References: Elias, M., Gompert, Z., Jiggins, C. & Willmott, K. (2008). Mutualistic interactions drive ecological niche convergence in a diverse butterfly community, Plos Biology, 6, 2642-2649.