Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction

Gerardo Ceballosa,1, Paul R. Ehrlichb, and Peter H. Ravenc
aInstituto de Ecología, Universidad Nacional Autónoma de México, 04510 Ciudad de México, México; bCenter for Conservation Biology, Department of

Biology, Stanford University, Stanford, CA 94304; and cPlant Science Department, Missouri Botanical Garden, St. Louis, MO 63110 Contributed by Gerardo Ceballos, March 22, 2020 (sent for review December 26, 2019; reviewed by Thomas E. Lovejoy and Jorge L. Soberon)

The ongoing sixth mass species extinction is the result of the destruction of component populations leading to eventual extirpation of entire species. Populations and species extinctions have severe implications for society through the degradation of ecosys- tem services. Here we assess the extinction crisis from a different perspective. We examine 29,400 species of terrestrial vertebrates, and determine which are on the brink of extinction because they have fewer…