From antagonism to mutualism: inferring the origins and consequences of the multiple emergence of brood-site pollination on weevil super-diversification – POLLIDIV

Weevils are the most diverse phytophagous insects on Earth, and a typical example of evolutionary radiation (~62,000 described species). While they are commonly seen as detrimental herbivores, recent works have demonstrated their unexpected and unique ability to engage in new brood-site pollination mutualism with plants over evolutionary times. In such interaction, the weevil larvae grow in plant tissues while the adults ensure the pollination of the host plant. With at least ten convergent emergences of brood-site pollination along their evolution, this group provides for the first time “evolutionary replicas” to explore a significant aspect of the evolution of plant-insect interactions: the transition from antagonism to mutualism. The project POLLIDIV will combine the expertise of phylogeneticists, weevil specialists, and macroevolutionary biologists to investigate the origin and evolutionary consequences of the emergence of mutualism between plants and weevils. Our hypothesis is that the unexpected diversity of pollinating weevils can be explained by their colonization of a large number of plants in the past, followed by co-diversification with plants. To test this hypothesis, we will first develop a new set of genetic probes based on newly generated high-quality whole genomes to provide a robust phylogenetic framework for the emergence of brood-site pollination in weevils, which is still not resolved to date. In a second time, we will focus on three well-sampled tribes of weevils containing genera with contrasted ecologies (mutualists and antagonists) to infer the differential diversification rates and abilities to shift between plant lineages between them. The resulting patterns will provide significant insights on the deeply intertwined macroevolutionary success of plants and phytophagous insects.