Ant‐Mediated Ecosystem Functions Along a Tropical Elevational Gradient

Abstract

Aim Elevational gradients are excellent systems to study biodiversity variation, yet the ecosystem functions performed by animals along these gradients are poorly understood. We assessed tropical elevational patterns of ant‐mediated seed removal, insect predation and the phylogenetic diversity of the local ant assemblages performing these functions as well as the effects of climate and productivity. Location Southeast Brazil, Atlantic Forest. Taxon Ants. Methods We sampled ant‐mediated seed removal and insect predation across 20 transects, comprising an elevational gradient of approximately from 0 to 1000 m a.s.l. We extracted standardized phylogenetic metrics of the assemblages performing the functions: Faith's PD (SES PD), mean pairwise distance (SES MPD), and mean nearest taxon distance (SES MNTD). We also extracted climatic and productivity predictors for each transect. We then used generalized additive models to evaluate the responses of each function and their phylogenetic metrics along elevation, climate and NPP. Results Both ant‐mediated functions and species richness decreased along the elevational gradient, peaking at the same mid‐elevation, while SES MNTD increased linearly with elevation. Both ant‐mediated functions were positively correlated with temperature. However, we found that phylogenetic richness (SES PD) was lower in warmer and more seasonal environments, while phylogenetic divergence (SES MNTD) was also lower in warmer but drier environments. Main Conclusions Our findings suggest that diversity is linked to ecosystem functioning along the elevational gradient. Although high‐elevation assemblages may show greater evolutionary potential because they comprise distantly related taxa, ecosystem functions might be more vulnerable to species loss. Additionally, we highlighted that although elevated temperatures may boost ecosystem functioning in the short term, when acting together with increased seasonality and dryness, as expected under climate change, they could heighten the vulnerability of the ants responsible for these functions, potentially compromising ecosystem resistance and resilience in a changing world.

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