Discussion
We found that environmentally heterogeneous ecotones influenced the speed of trait evolution, affecting both the rate and time of diet transitions in sigmodontine rodents. Ecotone species’ diet changed little from the ancestral diet when compared to core species. Furthermore, an interaction between position and habitat type indicated that a broader environmental context dictates the rates and time of diet evolution. Spatial variation on assemblage-level tip-based metrics revealed regions with slow- and fast-evolving species. Finally, phylogenetic uncertainty can influence the estimates of rates and time of trait evolution, as well as the inference about the effect of variables on such estimates.