The scent of sun worship: basking experience alters scent mark composition in male lizards
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Signals used in female choice should honestly advertise the benefits that males can provide, with direct benefits often argued as being more important than indirect benefits. However, the nature of direct benefits in species without paternal care or nuptial gifts is poorly understood. Previous studies on lizards suggest that females decide where to settle and assumedly who to mate with based on information contained in scent marks from territorial males. Access to high-quality thermal resources is crucial for female reproductive success. Females may therefore be able to detect and exploit thermal-induced variation in the chemical composition of male scent marks when assessing the quality of his territory. We show that the amount of time male wall lizards (Podarcis muralis) are allowed to bask significantly alters the chemical composition of their femoral secretions used in scent marking. The direction of the change is consistent with adaptive plasticity to maintain signalling efficacy under warm conditions that increase evaporation of femoral secretions. The compounds affected by basking experience included those previously associated with male quality or shown to mediate male–male competition in lizards. However, whilst female lizards could discriminate between scent marks of males that had experienced different basking conditions, they did not preferentially associate with the scent from males from high-quality thermal conditions. These results highlight the potential importance of a previously neglected environmental effect on chemical signalling. We suggest thermal effects may have significant consequences for scent-mark composition in variable environments, with potential repercussions on olfactory communication in lizards.
KeywordsChemical signalling Thermal plasticity Podarcis muralis Scent mark Female choice
We would like to thank Selina Helenius for the help in collecting data and Chloé Leroy for the help with the chemical analyses. We are grateful to an anonymous reviewer for helpful comments on a previous manuscript. We would also like to thank Ben Daly, Pau Carazo, Dan Noble, Alex Pigot and Tristram Wyatt for helpful discussions and James Stroud and Fiona Moultrie for their help in catching lizards. This work was supported by a BBSRC studentship and Pembroke College Research Grant (both to RJPH), a FP7 Marie Curie Fellowship (to GMW), and the British Ecological Society, the National Geographic Society, the Royal Society of London and the Knut and Alice Wallenberg Foundations (all to TU).
The authors declare that all work described in this manuscript complies with the laws of the UK. All work was approved by the University of Oxford’s Local Ethical Review Process.
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