We are not all the same: The role of intrapopulation trait variability in shaping functional strategy and performance of widespread species.

Abstract

Functional traits influence plant performance and adaptability to environmental changes, as environments select optimal phenotypes, leading to diverse functional strategies. While trait-based studies emphasize intraspecific trait variability (ITV) in response to environmental variations, the effects of phenotype-environment relationships and ITV on the performance of widely distributed species remain unclear. Here, we evaluated how intraspecific phenotypic dissimilarity (IPD) between populations, ITV within populations, and biotic and abiotic factors influence the functional strategies and performance of eight Epidendrum fulgens populations along a latitudinal gradient on the Brazilian coast. Data on seven functional traits (leaf and anatomical) and performance (fruit set over two years) were collected, and biotic and abiotic factors were analyzed using bioclimatic variables and phylogenetic structures of plant communities. The functional space was evaluated using PCA, and GLMs were employed to assess the impacts of environmental factors, species interactions, IPD, and ITV on performance. Populations exhibited distinct functional strategies, with warmer, wetter environments favoring acquisitive strategies and colder, drier areas favoring conservative ones. Notably, IPD and, unexpectedly, were correlated with improved performance, with IPD mitigating temperature stress. ITV within populations had significant but context-dependent effects on outcomes. In summary, our findings highlight the role of intrapopulation trait variability in driving shifts in functional strategies across environmental gradients, improving performance through increased phenotypic dissimilarity. The interplay of ITV within populations, environmental conditions, and interspecific competition shapes plant strategies and performance across diverse habitats.