Roles of ecology, climate, and geography in the macroevolution of insect pheromone diversity

Chemical signalling is the dominant form of intraspecific communication in insects, and sex pheromones involved in long-range mate recognition are particularly widespread and diverse. Although efforts have been made to catalogue this intriguing diversity, remarkably little is known about evolutionary drivers and constraints of sex pheromone variation among species. We aimed to test multiple hypotheses about the evolution of this diversity in relation to geography, climate, host plant affiliation, and phylogeny. To do this, we filtered hundreds of published pheromone papers and assembled a dataset of female-produced sex pheromones and male-produced aggregation-sex pheromones for over 300 insect species. Our dataset includes two beetle groups (Cerambycidae and Curculionidae) and four moth families (Noctuidae, Tortricidae, Geometridae, and Pyralidae), with each family represented by at least 40 species. These six groups lack comprehensive phylogenies but are otherwise ideal for macroevolutionary analyses, as they are among the most intensively studied in the insect chemical ecology literature. Thus, we downloaded mitochondrial and nuclear sequence data from Genbank and reconstructed a phylogenetic tree for each family. We also obtained geographic, ecological, and climatic data for our target species by synthesizing geographic occurrence records from GBIF, climatic data from WorldClim, and host plant details from online databases. Finally, we used generalized linear models to test for effects of host plant affiliation, climate, geography, and phylogeny on pheromone diversity within each of our focal insect groups. Our talk will present the results of these family-specific analyses, along with their broader implications for our understanding of insect pheromone evolution.