How Does Intraspecific Trait Variation Influence the Climate Niche Breadth of Tropical Tree Species?

Abstract: With the contribution of intraspecific trait variation (ITV) to ecological processes being increasingly appreciated, its role in defining niche characteristics arises as a topic of interest. I hypothesised that species with a high magnitude of ITV would occupy a larger climate niche breadth than species with little ITV. Trait and occurrence data for 211 angiosperm tree species across Puerto Rico was used to investigate this hypothesis. Multiple indices for climate niche breadth (NB) and intraspecific variation were calculated, after which regression tests were performed to identify and characterise any relationships between NB and ITV. I found consistent positive correlations between niche breadth and intraspecific variation values (a single negative result was present), supporting the hypothesis that ITV of functional traits has a positive influence on climate niche breadth. These results highlight the contribution of ITV to species distribution, though the mechanisms behind this relationship are unclear and present a question for future study.