Unveiling the Dietary Selection of Lowland Tapirs (Tapirus terrestris) in a Tropical Rainforest

Large terrestrial herbivores play crucial roles in shaping ecosystem structure and function through their foraging activities. Still, the dietary ecology of elusive tropical species remains poorly understood. We investigated the diet composition of lowland tapirs (Tapirus terrestris), the largest terrestrial herbivore in the Neotropics, using DNA metabarcoding of fecal samples from 31 latrines in Carlos Botelho State Park, Brazil. We characterized local plant communities through vegetation plots and analyzed five leaf economic spectrum (LES) traits from both consumed and surrounding vegetation to assess selective feeding patterns. Lowland tapirs consumed 61 plant species from 69 genera and 46 families, predominantly those from the Melastomataceae, Asteraceae, and Myrtaceae families. Beta-diversity analysis revealed high compositional turnover among latrines, with a high dissimilarity index, indicating that the samples being compared are distinct in species composition. The plant composition in tapir diets differed significantly from that of the surrounding vegetation, suggesting that this species forages on distinct plant species across its extensive home range rather than consuming locally abundant species. Finally, the functional trait analysis revealed no significant differences between the dietary species and the surrounding vegetation in LES traits. Tapirs consumed plants that spanned both "fast" (high specific leaf area and high nitrogen content) and "slow" (high leaf dry matter content and thick leaves) strategies, indicating a broad dietary tolerance rather than trait-based selectivity. This suggests that tapirs can adapt to diverse plant textures and nutritional profiles, browsing on leaves ranging from tough to softer and more digestible. Our findings demonstrate that lowland tapirs exhibit generalist feeding strategies, which promote high plant species turnover, potentially contributing to the maintenance of tropical forest diversity, as observed in the Atlantic forest. Given the critical threats facing this endangered megafauna, understanding their generalist diet is essential for developing effective conservation strategies.