Impacts of Pleistocene extinctions on the biomass and energy use of local mammal assemblages around the world

Many of the world's megafaunal species went extinct during the late
Quaternary, leading to dramatic reductions in community and ecosystem
functioning. While the nature and severity of the extinctions are well
documented on global and continental scales, less is known about
local-scale impacts. We quantified the biomass and energy use of 292
pre-extinction and 360 post-extinction fossil assemblages from around the
globe to determine effects on large mammal communities. Assemblage energy
use was calculated from metabolic rates obtained for 562 individual
species, and was compared to species richness along with indicators of
taphonomy, archaeology, and biogeography, using three analytical methods:
least-squares orthogonalization regression, spatial autoregression, and
linear mixed effects model analysis. Globally, total biomass and energy
use are greatly reduced in post-extinction assemblages. Human-accumulated
assemblages are further homogenised post-extinction due to their high
abundances of domesticated species. The presence of domesticates greatly
altered the biomass and energy use of assemblages post-extinction,
producing strong energetic variation across continents that differs
considerably to pre-extinction patterns. This fundamental anthropogenic
alteration of communities further exacerbated the impacts of Pleistocene
extinctions, even in less severely impacted regions. The results show how
human activities have altered mammalian communities for many thousands of
years.