Appendix A. Perfume differentiation in orchid bees. Fig. A1 shows a rotating, three-dimensional fragrance space of Euglossa spp. on Barro Colorado Island, Panama, in which the multidimensional scaling plot is based on the same data and analysis as the two-dimensional representation in Fig. 2a, but allows one additional dimension and thus accommodates more of the variation in the underlying similarity matrix (stress = 0.15). Fig. A2 is a full version of Fig. 4.