Diet states
We used the percentage of animal and vegetal items included in the diet of sigmodontine rodents from the Elton Traits v.1 database (Wilman et al. 2014). The database has suitable resolution to characterize rodent diet with high detail. We allocated each rodent species to one of four diet states: 1) insectivores (≥ 50% of the diet comprised by insects, < 50 % of the diet comprised by plants and fruits/seeds); 2) plant-eaters (≥ 50% plants, < 50% of insects and fruits/seeds); 3) fruit and seed-eaters (≥ 50% fruits/seeds, < 50% of insects and plants); and 4) generalists (several types of food items composing < 50% of the diet). We used these percentage cut-offs because most sigmodontine species are omnivorous (Paglia et al. 2012; Patton et al. 2015; Maestri et al. 2017). Thus, few of them would be included in a non-omnivore group if we were to use higher percentage cut-offs. Since diet data were lacking for 33 of the 350 species having distribution and phylogenetic data, we imputed the percentage of consumed items for these species using a random forest algorithm without the phylogeny to ensure the independence between trait and phylogeny (Stekhoven and Buehlmann 2012).