Environmental versus phylogenetic control of leaf anatomical traits in Fabaceae, across a continental scale

Leaf anatomical traits influence light absorption and gas exchange, thereby impacting plant growth and ecosystem function. However, the relative importance of environmental variables versus phylogenetic history in explaining leaf anatomical trait variation remains unclear.

We analyzed eight leaf anatomical traits and 14 environmental variables across 141 species of Fabaceae from 62 genera and 108 sites across China, using phylogenetic comparative analyses and variance partitioning.

Our results reveal that the phylogenetic signal in leaf anatomical traits is relatively constant after considering growth form, indicating that phylogenetic conservatism in these traits is not driven by differences among growth forms. The relationships between leaf anatomical traits and environmental variables are stronger, and the regression slopes between them steeper, when phylogenetic history is accounted for. Variance partitioning demonstrates that phylogeny accounts for less trait variation than environmental variables.

The first comprehensive analysis of leaf anatomical trait variation across Fabaceae species at a large spatial scale provides valuable insights into trait-environment relationships and underlines the importance of considering phylogeny to fully understand plant adaptation.