University of Wyoming Laramie, Wyoming, United States
The success of individuals in their environment is mediated by their traits, and differences in individual performance scale up to determine population and community dynamics. Traits may vary strongly among individuals within species, and this intraspecific trait variation (ITV) can influence individual- and species-level performance. Understanding how traits vary within species through space and time and how this variation affects species’ performance in different environments should therefore improve our ability to explain and predict species distributions and community structure along environmental gradients. Here, we synthesize the results of several studies in which we quantified patterns of ITV of woody plants in Patagonian forests across environmental gradients and tested links between ITV, demographic performance, and species distributions. Our key findings are that 1) ITV accounts for a substantial proportion (in some cases the majority) of community-level trait variation and drives community-level shifts in leaf economic traits across resource availability gradients, but is less important for leaf size and wood density; 2) intraspecific phenological variation in leaf traits may be similar to or greater than interspecific variation, and this variation can modify or even reverse species rankings for a number of leaf traits; 3) species that had high ITV and matched their leaf traits to local environmental optima were able to achieve wide niche breadth along light and soil nutrient availability gradients; and 4) although wood density and leaf size explained differences in performance (growth) of tree species along a strong precipitation gradient, accounting for ITV did not improve predictions of growth. Together these results show that ITV contributes strongly to the overall functional diversity within and among communities, but this variation is not necessarily strongly linked to species’ performance.
