Evolutionary trends of leaf traits for angiosperm tree species: a phylogenetic analysis

Background/Question/Methods

The diversity of plant functional traits has attracted considerable attention for a long time. This diversity is a product of both the adaptation to local climate and environment and a legacy from their ancestors. To what extent a species retain its ancestral traits, however, is still an open question.  Here using the leaf traits data from the GLOPNET database (Wright et al., 2004, Nature 428, 821-827), we analyzed the evolutionary trends of leaf lifespan (LL), leaf mass ratio (LMA), leaf nitrogen (N) and phosphors (P) contents,  leaf photosynthesis capacity (Amax) and dark respiration rate (Rd) for angiosperm tree species. 

Results/Conclusions

Statistical analyses show that at the order level, all the six leaf traits are closely related with their phylogenetic position in the angiosperm tree of life. Along the gradient from the oldest to the youngest lineages, there is an evolutionary trend towards decreasing LL and LMA, and increasing N, P contents and consequently the rates of Amax and Rd, especially when they are normalized by leaf mass. These trends are less obvious within plant orders. Hence evolution tends to drive plants to be more efficient in light interception and carbon assimilation. Our results also indicate a strong phylogenetic constraint of leaf ecophysiological traits at global scale.