Seasonal stability and species specificity of environmentally acquired chemical mating signals in orchid bees

Traits that mediate reproductive isolation between species, such as those involved in mate choice and/or recognition, are predicted to experience stabilizing selection towards the species mean. Male orchid bees collect chemical compounds from many sources, such as plants and fungi, which they use as a perfume signal (pheromone) during courtship display. Environmentally acquired signals are more prone to variation as source availability can vary through space and time. Here, we investigate the seasonality and species-specificity of male perfumes across an entire year in three sympatric species of Euglossa orchid bees. Our analysis revealed considerable within-species variation in perfumes. However, species-specificity was maintained consistently throughout the year, suggesting that these perfumes could play an important role in reproductive isolation. Our analysis also identified strong correlations in the abundance of some compounds, possibly due to shared collection sources between species. Our study suggests that orchid bee perfumes are robust in the face of environmental changes in resource availability.