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).