Format: ORAL

Edeline Gagnon1,2,3*Ludwig Baldaszti2,4Peter Moonlight5Sandra Knapp6Caroline E. R. Lehmann2,4Tiina Srkinen2

1Department of Integrative Biology, University of Guelph, Guelph, ON, Canada 2Tropical Diversity Section, Royal Botanic Garden Edinburgh, Edinburgh, United Kingdom 3Chair of Phytopathology, TUM School of Life Sciences, Technical University of Munich, Freising, Germany 4School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom 5Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland 6Natural History Museum, London, United Kingdom

The evolution of geophytes in response to different environmental stressors is poorly understood largely due to the great morphological variation in underground plant organs, which includes species with rhizomatous structures or underground storage organs (USOs). Here we compare the evolution and ecological niche patterns of different geophytic organs inSolanumL., classified based on a functional definition and using a clade-based approach with an expert-verified specimen occurrence dataset. Results from PERMANOVA and Phylogenetic ANOVAs indicate that geophytic species occupy drier areas, with rhizomatous species found in the hottest areas whereas species with USOs are restricted to cooler areas in the montane tropics. In addition, rhizomatous species appear to be adapted to fire-driven disturbance, in contrast to species with USOs that appear to be adapted to prolonged climatic disturbance such as unfavorable growing conditions due to drought and cold. We also show that the evolution of rhizome-like structures leads to changes in the relationship between range size and niche breadth. Ancestral state reconstruction shows that inSolanumrhizomatous species are evolutionarily more labile compared to species with USOs. Our results suggest that underground organs enable plants to shift their niches towards distinct extreme environmental conditions and have different evolutionary constraints.