Evidence for partial overlap of male olfactory cues in lampreys.

Animals rely on a mosaic of complex information to find and evaluate mates. Pheromones, often consisting of multiple components, are considered to be particularly important for species-recognition in many species. Although the evolution of species-specific pheromone blends is well described in many insects, very few vertebrate pheromones have been studied in a macro-evolutionary context. Here, we report a phylogenetic comparison of multi-component male odours that guide reproduction in lampreys. Chemical profiling of sexually mature males from eleven species of lamprey, representing six of ten genera and two of three families, indicated that the chemical profiles of sexually mature male odours are partially shared among species. Behavioural assays conducted with four species sympatric in the Laurentian Great Lakes indicated asymmetric female responses to heterospecific odours, where Petromyzon marinus were attracted to male odour collected from all species tested, but other species generally preferred only the odour of conspecifics. Electro-olfactogram recordings from P. marinus indicated that although P. marinus exhibited behavioural responses to odours from males of all species, at least some of the compounds that elicited olfactory responses were different in conspecific male odours compared with heterospecific male odours. We conclude that some of the compounds released by sexually mature males are shared among species and elicit olfactory and behavioural responses in P. marinus, and suggest that our results provide evidence for partial overlap of male olfactory cues among lampreys. Further characterization of the chemical identities of odour components is needed to confirm shared pheromones among species.