Genetic Diversity of Sodefrin-Variant Pheromones and Pheromone Responsiveness in Subspecies of the Japanese Sword-Tail Newt .

Experiments were conducted to examine whether the abdominal glands of subspecies ( and express different mRNAs for sodefrin-like female-attracting pheromone precursors. A precursor mRNA encoding a novel sex pheromone candidate, [Gln]sodefrin, was widely detected in the abdominal glands of both of subspecies. Female partners exhibited a considerable preference for synthetic [Gln]sodefrin. Thus, [Gln]sodefrin was designated caudarin. In , the abdominal glands of males expressed sodefrin precursor mRNA as well, and sodefrin was also effective in attracting female partners. In addition to caudarin precursor mRNA, the abdominal glands of males expressed silefrin ([Leu, Gln]sodefrin) precursor mRNA, as reported previously. Moreover, imorin, a male-attracting pheromone previously identified in females, was effective in attracting males but not males of . Molecular phylogenetic analysis indicated that trans-specific possession of sodefrin genes was likely because of gene occurrence preceding speciation of and , and that the additional occurrence of silefrin in possibly resulted from duplication of the caudarin gene. Differences in pheromone components among species and subspecies reflect the speciation route estimated by previous molecular genetic analyses.