The counteracting effects of human-driven speciation and extinction on mammal species richness and phylogenetic diversity (Q6692384)

Human activities are causing massive increases in extinction rates, but may also lead to drastic increases in speciation rates – for example following the human-mediated spread of species to otherwise unreachable landmasses. The long-term net anthropogenic effects on biodiversity, therefore, remain uncertain. The aim of this paper is to assess the combined anthropogenic effects of extinctions and speciations on biodiversity over geological time scales. We estimate known anthropogenic and predicted future extinctions based on Red List categories from the International Union for Conservation of Nature. We infer potential anthropogenic speciations assuming that all introductions to isolated landmasses will over time evolve into distinct species. We then estimate changes in regional and global species richness and phylogenetic diversity due to these extinctions and speciations. We show that if all species introduced into new landmasses develop into new species, the number of anthropogenic speciation and extinctions eventually become similar. However, even after accounting for an anthropogenic increase in speciation, our estimates suggest recovery times for phylogenetic diversity of several million years. Our results highlight that while humans are causing drastic biodiversity losses, human-driven speciation could eventually counterbalance these losses in species numbers, while phylogenetic diversity at least within our simulation scenarios would remain permanently reduced. This conclusion, however, requires our pressures on biodiversity to cease soon and requires us to consider geological timescales rather than changes over this century.