Shared and divergent expression domains on mimetic Heliconius wings

Heliconius butterfly wing patterns show repeated convergence between species and have adaptive value in mimicry and mate choice, offering an opportunity to connect adaptive changes in phenotype with their underlying genotypes. Here we study forewing ommochrome pigmentation in Heliconius melpomene. We clone two new ommochrome pathway genes for the Lepidoptera, karmoisin and kynurenine formamidase (kf), and analyze the expression patterns of all known ommochrome genes across pupal wing development. In combination with published work, this generates the first comparative gene expression data for the co-mimics Heliconius erato and H. melpomene. In both species cinnabar expression correlates with the forewing band, but the expression pattern of vermillion differs significantly between the mimics. This demonstrates that both shared and divergent expression patterns are associated with mimetic phenotypes between Heliconius species. Two genes not studied in H. erato, scarlet and possibly kf, also show enhanced expression in the forewing band of H. melpomene, implying co-ordinated upregulation of several members of this biosynthetic pathway during pattern formation.