Format: ORAL

Rowan J. Schley(1) Alex D. Twyford(2,3) Flavia Pezzini(3) Catherine Kidner (2,3) Rosalia Pieiro(4) Maria-Jose Endara(5) James Nicholls(6) Kyle G. Dexter(2) R. Toby Pennington(1,3)

(1) University of Exeter (2) University of Edinburgh (3) Royal Botanic Garden Edinburgh (4) University of A Coruña (5) Universidad de Las Americas, Quito (6) CSIRO, Canberra

Radiations that generate species-rich clades are fundamental in the evolution of diversity. Hybridisation can facilitate radiations through transfer of adaptive variation, catalysing rapid divergence. Much of the hyperdiverse neotropical tree flora was generated by radiations, but the influence of hybridisation on their evolution remains unexplored. Rainforest tree communities are subject to relentless insect herbivory, such that co-occurring tree species differ significantly in herbivore defence chemistry, with rare defences most effectively overcoming local herbivores. Chemical defences show evidence of divergent evolution between sister species of Inga, a chemically diverse genus of 300 rainforest trees that typifies rapid neotropical tree radiations. Thus, here we ask whether hybridisation catalysed the rapid radiation of Inga through passage of rare herbivore defence traits. We use phylogenomic approaches to first understand whether reticulation preceded rapid diversification in Inga, and hence whether hybridisation may underlie this radiation. Then, using whole-genome resequencing of 520 Inga accessions comprising 40 species, we ask whether hybridisation facilitates the transfer of linkage blocks containing rare chemical defence loci between species. Overall, we aim to assess whether ecological divergence facilitated by transfer of adaptive variation through hybridisation helped to generate the unmatched diversity of rainforest trees.