Characterizing the Molecular Basis of Supergene Mimicry in Butterflies - Characterizing the Molecular Basis of Supergene Mimicry in Butterflies Project Summary Why is life on Earth so diverse? How do these diverse forms arise, both over evolutionary time and during development? What are the functional molecular and genetic changes that underlie the fantastic organismal diversity we see in the natural world? My research focuses on these big questions related to the origin of biodiversity, but I do so through the lens of mechanism. Butterflies, and butterfly wing patterns in particular, offer an excellent system to unlock the functional molecular and genetic mechanisms responsible for organismal evolution because of their natural diversity, a long history of research that puts this diversity in a much-needed ecological context, and our success at establishing genomic and genome editing tools for butterflies. My research team and I study diversity using multiple approaches, including molecular and population genetics, genomics, developmental biology techniques, functional genomics, genome editing, neurobiology, behavioral experiments, and computation. The ultimate goal of this work is very fundamental: I strive to characterize the functional mechanisms responsible for historical evolutionary processes while also uncovering basic principles of biological patterning, development, and behavior. Much of our research is focused on the phenomenon of sex-limited polymorphism, which is widespread in animals but is not well understood in any organism. “Supergene” mimicry in the swallowtail butterfly Papilio polytes stands out as a particularly striking example of sex-limited polymorphism and one that is amenable to functional characterization. While much theoretical work has explored the evolutionary dynamics of supergene mimicry, we are just beginning to unpack its molecular and developmental basis. Previously we determined that the gene doublesex controls the mimicry switch in P. polytes and we have studied the origin and evolution of mimicry, behavioral aspects of mimicry, natural selection in nature, and we have developed tools and methods for CRISPR and multiple functional genomics assays. Using these tools, we have begun to characterize the cis-regulatory architecture of doublesex, as well as the gene regulatory networks that are modified by doublesex to produce novel mimetic wing patterns. Over the next five years, we will investigate the functional basis of supergene mimicry in P. polytes by integrating genomics, functional genetics, molecular and developmental biology, providing the single most comprehensive investigation of its kind. Furthermore, we will greatly expand the scope of our analyses by branching out on the butterfly phylogeny to functionally characterize parallel evolution of supergene mimicry in other butterflies. Our work will greatly expand the known role of the sexual differentiation pathway and generate general insights into fundamental evolutionary genetic processes of convergence, cis-regulatory evolution, and gene co-option.
