Courtship pheromones in mudpuppies and waterdogs (Necturus, Proteidae)

Mudpuppies and waterdogs (genus Necturus) are relatively big, paedomorphic salamanders that inhabit rivers and lakes of North America. Together with the olms (Proteus anguinus), their blind European relatives, they are the only extant representatives of the family Proteidae. Necturus species are characterised by longevity and a prolonged time for reaching sexual maturity. They reproduce by internal fertilisation, in which females pick up spermatophores deposited by the males in the environment. Because several internally fertilising salamander families are known to use pheromone communication to optimise their reproductive strategy, we studied the courtship behaviour of Necturus species to
identify behavioural patterns related to pheromone transfer. Our observations revealed that both sexes wag their tail in proximity of an individual of the opposite sex. This behaviour, in combination with the fact that these species possess cloacal glands that are homologous to pheromone glands of other salamander families, indicates that chemical communication plays an important role during courtship. We then combined transcriptomics of the pheromone glands, proteomics of courtship water and molecular phylogenetic analyses to
further identify candidate pheromones in this urodelan lineage. Our study fills an important gap of information on pheromone use in an approximately 150 million year old evolutionary lineage of salamanders.