The role of leaf and root functional traits in the Espeletiinae (Asteraceae) radiation

Premise

Key innovations within a group result in ecological divergence. Those innovations involve functional traits that may reflect the species' adaptations to environmental conditions and to interactions within the community. The subtribe Espeletiinae is considered an adaptive radiation due to their exceptional diversity. In this study, we explored the role that functional traits have in this radiation.

Methods

Nine functional traits (leaf and root) were measured in co-occurring species of five páramo complexes in Colombia. We used a principal component analysis to understand the climatic differences between complexes and to define the functional space of the species. Welch's ANOVA and t-test were used to unveil significant differences among co-occurring species. We also used normal mixture models (NMMs) to reassemble species based on the functional trait data.

Results

Páramo complexes were partially separated in climatic conditions of temperature and precipitation. Leaf traits exhibited more significant differences among co-occurring species within each complex compared to root traits. Espeletia glandulosa was the only species that showed a species-specific combination of traits and formed a cluster in the NMM analysis.

Conclusions

There is a more pronounced variation in leaf traits among co-occurring species, suggesting a potential ecological diversity driver. We propose that there is convergence and stabilization of traits, given the colonization of similar habitats by species belonging to Espeletiinae. We highlight the need for studying the role of other functional traits in the ecological differentiation of species within this group to elucidate how they coexist and cope with environmental conditions of the páramo.