High risk of extinction across the flowering plant tree of life.

Global biodiversity policies recognize the necessity to preserve evolutionary lineages, as their diversity underpins current and future benefits to people and the future of life on Earth. Plants are largely absent from global biodiversity assessments, resulting in a taxonomic imbalance that has undermined their conservation for decades. We present a tree of life and extinction risk estimates for all species of flowering plants (angiosperms), representing a global assessment of their threatened evolutionary history. We estimate that 21.2% of angiosperm evolutionary history is at risk of extinction and identify 9945 priority species that disproportionately account for total threatened evolutionary history. These prioritizations serve to redress imbalances between plants and animals, monitor conservation effectiveness, and optimize resource allocation in the face of increasing human pressures on biodiversity. Climate change and other massive global changes are increasing the risk of extinction for many species. Two papers in this issue address the extent of extinction risk to plants. Wang . used species distribution models to predict range shifts in response to climate change for more than 60,000 plant species. They found that 7 to 16% of these species will be at high extinction risk by 2100 across emissions scenarios. Forest . combined phylogenetic information with species extinction risk assessments to show that more than one-fifth of flowering plants’ evolutionary history is currently threatened, a ratio similar to that seen in vertebrate groups. Considering the extent to which people depend on the productivity and diversity of plants, these studies show what is at stake from uncurbed anthropogenic global change (see the Perspective by Scherson and Luebert). —Bianca Lopez