Format: ORAL

Guillaume Chomicki

Department of Biosciences, Durham University, Durham, United Kingdom.

Widespread in nature, mutualistic associations cooperative interactions between unrelated species are pivotal for the generation and maintenance of biodiversity. These partnerships vary from loose, facultative interactions between large guilds to tight, obligate interactions on which species depend for reproduction or survival. The Hydnophytinae is a clade of 105 species of epiphytic Rubiaceae, most of which form symbiotic mutualisms with ants. Despite its size, the Hydnophytinae have a higher rate of evolutionary transitions in mutualistic dependence magnitudes than mycorrhizal, pollination and seed dispersal mutualisms, making them an ideal model clade to study the evolution of mutualisms. I will synthesize a decade of work and show how integrative, phylogenetically-informed studies of Hydnophytinae ant/plant symbioses have shed major insights on our understanding of mutualisms as a whole. Using phylogenetic comparative methods, field experiments, comparative genomics and transcriptomics, 3D imaging, microbiology and modelling, I will show how mutualistic dependence is critical for determining the evolutionary stability of the partnership, its efficiency in trading resources, and show how it mediates trait evolution within and beyond those involved in the interaction. I will also show how the Hydnophytinae can help us resolve the paradox of multi-species mutualisms, and share new insights on mechanisms promoting obligate dependence between macro partners.