Phylogeny, ecology, and geography as drivers or constraints of pheromone macroevolution

Insects display outstanding pheromone diversity, but macroevolutionary patterns of chemical signal variation and their drivers have not been systematically studied in most groups. We aim to bridge this gap by synthesizing data on the composition of sex and aggregation-sex pheromones across more than 500 insect species in 8 families and three orders: Coleoptera, Lepidoptera, and Diptera. Within each of these families, we are reconstructing phylogenies from available molecular data and using phylogenetic comparative methods to identify the extent to which environment, geography, and evolutionary history drive or constrain pheromone diversification. Our preliminary results for Drosophila suggest, intriguingly, that these effects may be scale-dependent. While phylogenetic constraints shape lower-level compound variation, environmental constraints influence higher levels of chemical structural class diversity. Thus, different forms of selection on hierarchical levels of chemical structure may have contributed to the vast diversity of insect pheromones.