Conspecific male chemical cues influence courtship behaviour in the male newt Lissotriton boscai

Chemical information can have a direct or indirect influence beyond dyadic interactions. How chemical cues can alter communicating interactions where the transmitters of chemical cues do not participate is poorly understood. Chemical information plays an important role in the sexual behaviour of urodeles. Previous studies of the newt Lissotriton boscai and other salamandrids showed that males modify their courtship in presence of competitors to avoid courtship interferences. The aim of this study was to test whether L. boscai males assess the level of competition through chemical cues and adjust their courtship accordingly. In a first experiment, male courtship displays were recorded in aquaria containing their own chemical stimuli, or from another male. The duration and/or the number of several courtship displays were scored, and found that males decreased their courtship effort when the water contained chemical stimuli from another male. This experiment showed that semiochemicals can be sufficient to modify courtship displays without visual contact with transmitters of the chemical information, suggesting that males may adjust their courtship display to reduce reproductive costs. An additional experiment resembling chemically mediated residence asymmetries was then performed to examine whether territoriality is compatible with results of experiment 1, and found no evidence.