Relationships between climate, chemical signal composition, and behavior

Abstract

Many signals used in animal communication are shaped by natural and sexual selection imposed by characteristics of the physical habitat and receiver sensory systems, and retain little trace of phylogenetic similarity. Specific compounds may contribute to chemical signals directly, be metabolic byproducts or have some combination of these and other functions. To explore the functions of specific compounds and the chemical classes they belong to we used a genus of lizards that exploit a diverse array of habitat types. We compared the composition of chemical signals from twelve species of Sceloporus lizards, using gas chromatography-mass spectrometry (GC-MS) to characterize secretions and modern phylogenetic comparative methods to infer the relative importance of phylogenetic history, temperature and precipitation in signal composition. We also asked whether composition reflects rates of chemosensory behavior. Fatty acids were the most abundant class of compounds. We found that habitat temperature was negatively correlated to the proportion of unsaturated fatty acids comprising species' chemical signals. Rates of chemosensory behavior were positively correlated to the proportion of saturated fatty acids. We discuss the link between compound abundance and species habitat, phylogenetic history, and chemical behavior.