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Abstract

We present the first comprehensive morphospace of the shapes of lepidopteran wing scales, and we connect morphological diversity in scale shapes to phyloge- netic relationships within the Lepidoptera. The architectural complexity of wing scale shapes and colors arises from variation in the developmental program of just a single cell type. Significant advances have been made in understanding the developmental mechanisms that generate lepidopteran wing pattern diversity, but very little is understood about the causes or correlates of the diversity of scale shapes. The morphospace represents the shapes of 5250 wing scales from 132 species in 39 families that range across the Lepidoptera. It was prepared through Elliptic Fourier analysis on closed outlines. Using a Bayesian phylogeny, we find that, in certain clades, both the morphospace position and volume of convex hulls correlate with the phylogeny. We also assess differences in the amount of morphospace that each species occupies, and identify instances of evolutionary convergence and the appearance of novel shapes. Our morphospace reveals con- straints of variation in the shapes of wing scales, and we find that only a few lepi- dopteran groups have substantially expanded the realized shape space into new territory. Lastly, we connect certain scale shape features (e.g. scale width, scale length, and number of finger-like projections) to processes occurring during scale cell development.