Global gradients in intraspecific variation in vegetative and floral traits are partially associated with climate and species richness

Aim

Intraspecific trait variation (ITV) within natural plant communities can be large, influencing local ecological processes and dynamics. Here, we shed light on how ITV in vegetative and floral traits responds to large-scale abiotic and biotic gradients (i.e. climate and species richness). Specifically, we tested if associations of ITV with temperature, precipitation and species richness were consistent with any of from four hypotheses relating to stress-tolerance and competition. Furthermore, we estimated the degree of correlation between ITV in vegetative and floral traits and how they vary along the gradients.

Location

Global.

Time period

1975-2016.

Major taxa studied

Herbaceous and woody plants.

Methods

We compiled a dataset of 18,112 measurements of the absolute extent of ITV (measured as coefficient of variation) in nine vegetative and seven floral traits from 2,774 herbaceous and woody species at 2,306 locations.

Results

Large-scale associations between ITV and climate were trait-specific and more prominent for vegetative traits, especially leaf morphology, than for floral traits. ITV showed pronounced associations with climate, with lower ITV values in colder areas and higher values in drier areas. The associations of ITV with species richness were inconsistent across traits. Species-specific associations across gradients were often idiosyncratic and covariation in ITV was weaker between vegetative and floral traits than within the two trait groups.

Main conclusions

Our results show that, depending on the traits considered, ITV either increased or decreased with climate stress and species richness, suggesting that both factors can constrain or enhance ITV, which might foster plant-population persistence under stressful conditions. Given the species-specific responses and covariation in ITV, associations can be hard to predict for traits and species not yet studied. We conclude that considering ITV can improve our understanding of how plants cope with stressful conditions and environmental change across spatial and biological scales.