Globally, large mammals are in decline. Biological traits including low population densities and longer generation times make them particularly susceptible. Their losses can have wide-ranging ecological consequences, including dramatic reductions in total heterotrophic energy use. To determine the key drivers of variation in energy use, we calculated daily rates of energy flow across the globe for 241 ecological communities, encompassing 441 large mammal species, using camera trap inventories. These were scaled up from individual metabolic rates and compared with various climate, anthropogenic, geographic, and species richness variables using three analytical methods: model selection, spatial autoregression, and a multiple regression method that completely removes multicollinearity known as least-squares orthogonalization. Community energy use is significantly lower in the Neotropics and Australasia than in the Afrotropics and Eurasia. This pattern mirrors the spatial distribution of megafaunal extinction intensity during the Late Pleistocene. Rates not being greatly reduced in the Nearctic is a notable exception to this pattern, and is likely due to the high abundances of certain species not present in the other highly-impacted realms. There are also strong negative correlations between community per-gram rates of energy flow and species richness, indicating that megafauna persist mainly in more speciose communities. The strong geographic differences that dominate energy use patterns indicate that past mammal extinctions are the ultimate cause of modern energetic variation in large mammal communities. If so, then ongoing losses of large mammals will greatly impact community and ecosystem functioning.

The flora of California, a global biodiversity hotspot, includes 2387 endemic plant taxa. With anticipated climate change, we project that up to 66% will experience >80% reductions in range size within a century. These results are comparable with other studies of fewer species or just samples of a region's endemics. Projected reductions depend on the magnitude of future emissions and on the ability of species to disperse from their current locations. California's varied terrain could cause species to move in very different directions, breaking up present-day floras. However, our projections also identify regions where species undergoing severe range reductions may persist. Protecting these potential future refugia and facilitating species dispersal will be essential to maintain biodiversity in the face of climate change.