Effects of global warming on sensory ecology of rock lizards: increased temperatures alter the efficacy of sexual chemical signals

1. An almost neglected aspect of climate change is its effects on sensory ecology and sexual signals of animals. Signals used in intraspecific communication are expected to evolve to maximize efficacy under a given climatic condition, but it is unlikely that quick changes in environmental conditions could be compensated by similarly quick evolutionary changes in the design of signals. We predict that global warming will lead to a loss of efficacy of some sexual signals, with important consequences for sexual selection. 2. We examined experimentally the effects of global warming on the efficacy of chemical signals of a mountain lizard (Iberolacerta cyreni). 3. We first showed how environmental temperatures in the study area during the mating season of lizards have actually increased in the last years. Then, we tested whether female lizards were able to detect by chemosensory cues the males' scent marks (i.e. femoral secretions) that were experimentally maintained under current and predicted future temperature conditions. 4. Results showed that the efficacy (i.e. detectability and persistence) of scent marks is lower at high temperature. Moreover, we showed that scent-marked substrates maintained under high temperatures were not selected by females, in contrast to the selection of areas scent marked by males, when these substrates were maintained under normal temperatures. 5. Our study suggests that climate warming could lead to negative changes in the efficacy of sexual signals with potential consequences for the sexual selection and conservation of threatened lizard species.