Phylogenetic history shapes the composition of floral scents in a specialized pollination mutualism

Most studies of the chemical ecology of plant-pollinator interactions emphasize the role of pollinator-mediated selection in shaping floral scent composition. Nevertheless, phylogeny may constrain the metabolic pathways underlying these profiles, thereby influencing the evolutionary trajectory of the emitted signals. To investigate whether phylogenetic history constrains plant chemical communication, we used the obligate fig-fig wasp mutualism. We collected floral scents from receptive figs of 32 Ficus species, representing diverse lineages across tropical and subtropical regions, using dynamic headspace extraction. Chemical compositions were analyzed via gas chromatography-mass spectrometry and evaluated for the phylogenetic signal using multivariate analyses. Our results revealed a strong phylogenetic signal in the volatile organic compounds (VOCs) emitted by receptive figs. Conversely, using the same analysis, we found no relationship between the scent profile and the pollinator phylogeny. Our findings demonstrate, across diverse Ficus lineages, that phylogenetic constraints play a significant role in the diversification of VOC signals emitted by receptive flowers, suggesting constraints in the biosynthetic pathways of volatile compounds.