Behavioral Evidence for a Sex Pheromone in Female Roughskin Newts, Taricha Granulosa

Abstract

To determine if a chemical signal produced by female roughskin newts (Taricha granulosa) stimulates amplectic clasping in males, we recorded behavioral responses by males to scented plastic models of female newts. Female-scented models elicited robust amplectic clasping by male newts, whereas unscented models or models scented with male odors were rarely clasped by males. Models treated with female-scented water elicited clasping responses, but not as effectively as models that were scented by placing them in direct contact with females. Protease or heat treatment did not disrupt the clasp-eliciting activity in female-scented water. These findings provide evidence that a pheromone produced by female roughskin newts acts as a releasing stimulus that elicits a specific, stereotypical courtship response in males, and they suggest that the chemical signal is not proteinaceous.