Receptor for detection of a Type II sex pheromone in the winter moth Operophtera brumata

How signal diversity evolves under stabilizing selection in a pheromone-based mate recognitionsystem is a conundrum. Female moths produce two major types of sex pheromones, i.e., long-chainacetates, alcohols and aldehydes (Type I) and polyenic hydrocarbons and epoxides (Type II), alongdifferent biosynthetic pathways. Little is known on how male pheromone receptor (PR) genes evolvedto perceive the different pheromones. We report the identification of the first PR tuned to Type IIpheromones, namely ObruOR1 from the winter moth, Operophtera brumata (Geometridae). ObruOR1clusters together with previously ligand-unknown orthologues in the PR subfamily for the ancestralType I pheromones, suggesting that O. brumata did not evolve a new type of PR to match the novel TypeII signal but recruited receptors within an existing PR subfamily. AsegOR3, the ObruOR1 orthologuepreviously cloned from the noctuid Agrotis segetum that has Type I acetate pheromone components,responded significantly to another Type II hydrocarbon, suggesting that a common ancestor with TypeI pheromones had receptors for both types of pheromones, a preadaptation for detection of Type II sexpheromone