IRC-EB: The Evolution of a Pheromone Signaling System: From Molecules to Mating

Oregon State University, Corvallis OR

Investigators

Abstract

Lynne Houck - NSF 0110666 " IRC: The Evolution of a Pheromone Signaling System: From Molecules to Mating" LAY SUMMARY Terrestrial salamanders have a unique system of chemical communication. This system features non-volatile pheromones (chemical signals) that a male delivers to the female during courtship. The male courtship pheromone is produced by an enlarged gland under the male's chin, and the male taps this gland on the female's nose in order to deliver his pheromone. In their subsequent evolutionary history, plethodontids modified this pheromone delivery system in a variety of ways, including delivery methods in which the pheromone is "injected" into the female's circulatory system. This chemical communication system -unique among vertebrates- has been retained by diverse groups of plethodontids throughout their evolutionary radiation. Recently, it has been established that the plethodontid pheromone increases female sexual receptivity, as indicated by courtships that are completed more rapidly. It also has been determined that the pheromone is a protein. The amino acid sequence of this protein has been identified, as well as the nucleotide sequence of the gene that produces the pheromone protein. Furthermore, it has been established that the pheromone protein is in a cytokine family that includes interferons and interleukins. The phylogenetic setting for these discoveries offers an outstanding opportunity to investigate the evolution of the causal pathway from gene to protein to behavior. This project embraces a conceptual framework that is generally applicable to the study of evolutionary change in communication systems at multiple levels of organization.