The shape of adaptation: Evolution of venation patterns in plants

Leaf venation patterns display remarkable diversity across both living and fossil plant lineages, yet key questions remain about when and how these architectural differences emerged and what functional roles they serve. In their recent review, Mantos et al. explored the evolutionary history of venation traits and vein sizes across vascular plants using a dataset of 1,000 species, including both extant and extinct taxa. This comprehensive approach enabled them to reconstruct nearly 400 million years of venation network evolution. Their analysis focused on four venation traits across small, medium, and large vein size classes. Results revealed an evolutionary shift from simpler networks, characterized by fewer veins and more, corrugated loops, to more complex structures with more veins and smoother, less frequent loops. To assess how venation diversity changed over time, the authors performed a disparity-through-time (DTT) analysis. They identified two peaks in architectural diversification: one in the Paleozoic, followed by a decline during the Cretaceous, and a second, ongoing wave in the Cenozoic, largely driven by modern angiosperms. Environmental drivers were also examined. While no strong correlation was found between venation traits and climate variables such as CO₂ or temperature, a positive relationship emerged between insect diversification and specific traits in small and medium veins. These findings raise important questions about the multiple selective pressures underlying vein evolution, including the potential roles of hydraulic efficiency, mechanical support, and herbivory resistance. Increased vein density and smoother loops may have improved water transport, while also reinforcing leaf structure and protection from insect damage. Overall, this study offers a rich and nuanced view of leaf venation evolution, highlighting its complexity, diversity, and ecological significance. (Summary by Elisa De Meo, www.linkedin.com/in/elisa-de-meo-25415a20b) Nature Plants, 10.1038/s41477-025-02011-y.