The Kronforst Lab recently posted a new preprint describing the cis-regulatory elements in doublesex that control swallowtail butterfly mimicry. Contributors include Dr. Kronforst and lab members Nicholas VanKuren, Sofia Sheikh, Darli Massardo, and Wei Lu.
Abstract
The development of complex phenotypes requires the coordinated action of many genes across space and time, yet many species have evolved the ability to develop multiple discrete, alternate phenotypes1–3. Such polymorphisms are often controlled by supergenes, sets of tightly-linked mutations in one or more loci that function together to produce a complex phenotype4. Although theories of supergene evolution are well-established, the mutations that cause functional differences between supergene alleles remain essentially unknown. doublesex is the master regulator of insect sexual differentiation but functions as a supergene in multiple Papilio swallowtail butterflies, where divergent dsx alleles control development of discrete non-mimetic or mimetic female wing color patterns5–7. Here we demonstrate that the functional elements of the mimetic allele in Papilio alphenor are six new cis-regulatory elements (CREs) spread across 150 kb that are bound by DSX itself. Our findings provide experimental support to classic supergene theory and suggest that the evolution of auto-regulation may provide a simple route to supergene origination and to the co-option of pleiotropic genes into new developmental roles.