Human activity is altering the world’s zoogeographical regions

Human activity leading to both species introductions and extinctions is widely known to influence diversity patterns on local and regional scales. Yet, it is largely unknown whether the intensity of this activity is enough to affect the configuration of biodiversity at broader levels of spatial organization. Zoogeographical regions, or zooregions, are surfaces of the Earth defined by characteristic pools of species, which reflect ecological, historical, and evolutionary processes acting over millions of years. Consequently, it is widely assumed that zooregions are robust and unlikely to change on a human timescale. Here, however, we show that human-mediated introductions and extinctions can indeed reconfigure the currently recognized zooregions of amphibians, mammals, and birds. In particular, introductions homogenize the African and Eurasian zooregions in mammals; reshape boundaries with the reallocation of Oceania to the New World zooregion in amphibians; and divide bird zooregions by increasing biotic heterogeneity. Furthermore, the combined effect of amphibian introductions and extinctions has the potential to divide two zooregions largely representing the Old and the New World. Interestingly, the robustness of zooregions against changes in species composition may largely explain such zoogeographical changes. Altogether, our results demonstrate that human activities can erode the higher-level organization of biodiversity formed over millions of years. Comparable reconfigurations have previously been detectable in Earths history only after glaciations and mass extinction events, highlighting the profound and far-reaching impact of ongoing human activity and the need to protect the uniqueness of biotic assemblages from the effects of future species introductions and extinctions.