Phylogeny
We used one of the most updated and complete sets of phylogenies of sigmodontine rodents (Upham et al. 2019) for ancestral diet mapping and phylogenetic uncertainty analysis. The phylogenies have dated branches and were built from a supermatrix alignment of 11 genes which were extracted from a more inclusive mammalian supermatrix of 31 genes (Upham et al. 2019). The phylogenies were built using the multigene-approach for 279 of 413 extant sigmodontine species; the remaining 134 species were randomly placed at the tips of the phylogeny according to prevailing taxonomy. To consider phylogenetic uncertainty, we used a random sample of 100 phylogenies. An ancestral state was estimated for each node included in the evolutionary history of the 413 species, but we focused our analysis on the 350 species with distribution data that were included in the phylogeny. The mapping of ancestral characters was repeated for the 100 phylogenies in order to assess uncertainty in tip-based metrics (see below Ancestral character mapping ).