Global biogeographical regions reveal a signal of past human impacts

Ecologists have long documented that the world's biota is spatially
organised in regions with boundaries shaped by processes acting on
geological and evolutionary timescales. Although growing evidence suggests
that historical human impact has been key in how biodiversity is currently
assembled, its role as a driver of the geographical organisation of
biodiversity remains unclear. Using non-volant terrestrial mammals, we set
up a bioregionalization procedure focused on two data sets, one describing
the current ranges of terrestrial mammals, and another describing their
potential natural ranges in the absence of historic anthropogenic land
use. We then quantified the relative importance of anthropogenic land use
(5000 and 2000 years ago, and present time) to predict the current and
natural biogeographical regions across the Earth. In general, past and
present human land use were important predictors of current bioregions but
did not largely contribute to predicting natural bioregions. Past
anthropogenic land use seems to have left an imprint on the taxonomic
differentiation of some of the largest biogeographical realms, whereas
land use at present stands out as a driver of the taxonomic differences
between medium-sized subregions, i.e., within and among continents. Our
findings suggest that anthropogenic actions during the last millennia have
had a far-reaching effect on the spatial organisation of the Earth´s
non-volant mammals.