Unraveling the genetic tapestry of parallel red-green color vision evolution in butterflies

Red-green color vision is found in a variety of animals including primates and insects. Vision involves interactions between pigments and opsins, which are proteins that allow animal eyes to detect light. Yet not all vision systems work the same. The research will advance scientific knowledge of how animals can tell green, yellow, orange, and red apart. It will study how pigment-binding proteins partner with pigments and opsins to filter light in a way that works differently from the system in humans. It will further investigate whether the presence or absence of red-green color vision in insect pollinators is related to the color of flowers that they visit. This study will benefit society by providing new knowledge of how pollinators see and the plants they feed on. This knowledge can be used in the biologically guided design of parks and community gardens to enhance plant reproduction and pollinator and human health. Furthermore, certain pigments and the proteins that bind them have uses in the applied sciences, including manufacture of electronic color-changing devices and design of antioxidant and anticancer molecules. Understanding how new traits evolve is a central goal of evolutionary biology, as these innovations can fundamentally change the ecological interactions that drive biological richness, including interspecific interactions, niche shifts, and mating patterns. This research will investigate the evolutionary processes that drive the gain and loss of red-green color vision across Nymphalid butterflies. Building on previous work that identified a novel gene and molecular pathway underlying this trait, the researchers will examine evidence for parallel molecular evolution, characterize changes in gene regulation, and explore how repeated gain or loss of red-green color vision correlates with ecological variables. The research will combine genetics and gene expression with light microscopy, electrophysiology, immunohistochemistry, and behavioral assays in a phylogenetic framework to address four major questions. (1) Are the same mutations associated with parallel red- or blue-shifts in long wavelength opsin spectral sensitivity? (2) Is long wavelength opsin spectral tuning shaped by filter-pigment expression? (3) Are genetic processes underlying red-green color vision acquisition or loss different between species that have sexually dimorphic vs. monomorphic eyes? (4) Is the loss of red-green color vision associated with shifts in adult food sources, signals, or habitat? This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.