Environmental variables drive spatial patterns of trophic diversity in mammals.

Understanding environmental drivers of species diversity has become increasingly important under climate change. Different trophic groups (predators, omnivores and herbivores) interact with their environments in fundamentally different ways and may therefore be influenced by different environmental drivers. Using random forest models, we identified drivers of terrestrial mammals' total and proportional species richness within trophic groups at a global scale. Precipitation seasonality was the most important predictor of richness for all trophic groups. Richness peaked at intermediate precipitation seasonality, indicating that moderate levels of environmental heterogeneity promote mammal richness. Gross primary production (GPP) was the most important correlate of the relative contribution of each trophic group to total species richness. The strong relationship with GPP demonstrates that basal-level resource availability influences how diversity is structured among trophic groups. Our findings suggest that environmental characteristics that influence resource temporal variability and abundance are important predictors of terrestrial mammal richness at a global scale.

Protecting endangered species in the USA requires both public and private land conservation.

Crucial to the successful conservation of endangered species is the overlap of their ranges with protected areas. We analyzed protected areas in the continental USA to assess the extent to which they covered the ranges of endangered tetrapods. We show that in 80% of ecoregions, protected areas offer equal (25%) or worse (55%) protection for species than if their locations were chosen at random. Additionally, we demonstrate that it is possible to achieve sufficient protection for 100% of the USA's endangered tetrapods through targeted protection of undeveloped public and private lands. Our results highlight that the USA is likely to fall short of its commitments to halting biodiversity loss unless more considerable investments in both public and private land conservation are made.