Signal architecture: Temporal variability and individual consistency of multiple sexually selected signals

Abstract

Multiple signals should be favoured when the benefit of additional signals outweigh their costs. Despite increased attention on multiple-signalling systems, few studies have focused on signal architecture to understand the potential information content of multiple signals. To understand the patterns of signal plasticity and consistency over the lifetime of individuals we conducted a longitudinal study of multiple signals known to be under sexual selection in male lark buntings, Calamospiza melanocorys. Within years, we found extensive among-individual variation in all four plumage ornaments we measured. Surprisingly, there were few correlations among these signals, suggesting that individuals contain a mosaic of signals. Signals were only moderately repeatable across years, which indicates some signal plasticity or age related change. In some years, the direction of change in particular signals relative to the previous year was consistent for most individuals in the population, suggesting that broad scale ecological factors affected the ornament phenotype. Different ornaments were affected by different ecological or social factors because the population-wide shift in a given signal was independent of change in other signals. Our combined results suggest that different signals-including different components of the same color patch in some cases-provide diverse and independent information about the individual to signal receivers in the context of sexual selection.