The sensory environments individuals experience may influence the communication system of a species as a whole. Signal design, signalling activity, and the characteristics of sensory organs may change to ensure the tuning to local conditions. In this project, we focused on the effects of the environment on sexual communication in amphibians, using Lissotriton genus as a model. Optical (turbidity) and chemical characteristics (nitrate) do alter the expression of sexual signals and signalling effort. We also investigated the influence of the sensory environment on reproductive isolation between two newt species with a special emphasis on sexual UV communication. Interspecific hybridization requires incomplete reproductive barriers. At the behavioural level, hybrids may result from faulty species recognition, i.e. the inability of individuals to discriminate between potential conspecific from heterospecific partners. Sensory ecology theory postulates that the efficiency of recognition tasks varies with the sensory environment. Hence, under poor conditions of signal transmission, individuals may fail to perform accurate species discrimination. Therefore, habitat may strongly influence the hybridization rate and the spatial distribution of hybrids. Eventually, hybridization costs may induce character displacement on the whole communication system or habitat selection itself. The link between habitat, species recognition and hybridization is investigated in the Palmate newt Lissotriton helveticus and the Smooth newt L. vulgaris. These two newts hybridize in spite large a differentiation of their male sexual ornaments, a broad sympatric zone and a relatively long divergence time. The project aims at determining the effect of hybridization on the evolution of the visual communication system (signals, photoreceptors, sexual preferences) and habitat selection.