Wing patterns and speciation in North American Colias butterflies

Understanding how a genome can produce phenotypes like patterns, morphologies and behaviors is one of the core goals of biology. The wing patterns of butterflies are an excellent system for studying how genotypes produce phenotypes: they are a developmentally tractable phenotype, produced by varying the distribution of a small number of types of scale cells, the specialized cells that cover butterfly and moth wings, across a two-dimensional surface, Also, with butterflies we can often determine the selective pressures and evolutionary context of phenotypes at both a macro- and microevolutionary scale. I will talk about North American Colias butterflies, which exhibit an interspecies polymorphism in ultraviolet colour, used for male-to-female signalling during courtship and mating and which has contributed to speciation. Genetic mapping, antibody stainings, and CRISPR knockouts collectively indicate that the gene bric a brac controls whether UV-iridescent nanostructures develop in each species, illustrating how a master switch gene modulates a male courtship signal.