COS 59-6 - Expansion and convergence: the evolution of chemical diversity across the order Cycadales

Abstract: Specialized metabolites play essential roles in the ecology and evolution of plants, mediating both species interactions and environmental challenges. Because these biotic and abiotic pressures vary across habitats and ecosystems, plants are likely to evolve "specialized metabolite strategies" to better adapt to their ecological context. For instance, in environmentally challenging environments species will likely invest more resources into metabolites that can protect them from abiotic stress. Contrastingly, taxa found in species-rich habitats might invest more in compounds that modulate species interactions. Our goal was to test such expectations across environmental gradients in a globally distributed plant species.





We characterized evolutionary strategies across the order Cycadales, an ancient clade of gymnosperms found in a wide diversity of habitats across the tropics. We sampled the chemistry of more than 100 species using GCMS and HPLC and analyzed the data with both targeted and non-targeted metabolomics.



Here we show that species display significant convergence in chemical composition in similar habitats, driven by both phylogeny and ecological context. Notably, targeted metabolomics analysis shows that even within a single metabolic pathway, specific metabolites are strongly associated with different ecological challenges.





In conclusion, the present work shows that, at large phylogenetic and environmental scales, plants tailor their chemical architecture to better fit their ecological context. These findings shed light on the evolutionary potential of a limited diversity of active metabolic pathways to mediate abiotic and biotic stressors in a rapidly changing global climate.