Looping Network Meetings

#65 March 17, 2025

Monday 15:00 (Paris/Warsaw time)

Andres Baresch (University of Maryland, and NASA GSFC)

The functional role of multiple hierarchies in the venation network of leaves

Abstract:
The venation networks of laminated leaves evolved multiple times, and therefore, the developmental pathways that lead to patterns in vein organization are convergent. Direct and vein topology studies identify two developmental modes (with some variation), with leaves with little or no functional/morphological hierarchy and leaves where the network has multiple hierarchies. I will review the developmental basis and evolutionary patterns surrounding hierarchical vein networks and focus on functional consequences. A comprehensive and extensive survey of fossils and living taxa shows that high venation density and large laminas are relatively rare in the fossil record. I link the presence of multiple hierarchies in venation networks to most examples of high venation density. Tradeoffs in space allocation and functional specialization drive functional outcomes, and hierarchical networks are a requirement for high venation density, large lamina sizes and the combination of both characteristics. Large lamina sizes, dense venation networks and high photosynthetic capacity are characteristic of flowering plants and allow for novel ecological niches; arguably, fast-growing plants are evolutionarily rare, and leaf development and the rarity of multiple hierarchies likely contribute to this rarity.

Recording