Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines

Contributed by Paul R. Ehrlich, May 23, 2017 (sent for review March 28, 2017; reviewed by Thomas E. Lovejoy and Peter H. Raven)
July 10, 2017
114 (30) E6089-E6096
Commentary
Extinction tsunami can be avoided
Thomas E. Lovejoy

Significance

The strong focus on species extinctions, a critical aspect of the contemporary pulse of biological extinction, leads to a common misimpression that Earth’s biota is not immediately threatened, just slowly entering an episode of major biodiversity loss. This view overlooks the current trends of population declines and extinctions. Using a sample of 27,600 terrestrial vertebrate species, and a more detailed analysis of 177 mammal species, we show the extremely high degree of population decay in vertebrates, even in common “species of low concern.” Dwindling population sizes and range shrinkages amount to a massive anthropogenic erosion of biodiversity and of the ecosystem services essential to civilization. This “biological annihilation” underlines the seriousness for humanity of Earth’s ongoing sixth mass extinction event.

Abstract

The population extinction pulse we describe here shows, from a quantitative viewpoint, that Earth’s sixth mass extinction is more severe than perceived when looking exclusively at species extinctions. Therefore, humanity needs to address anthropogenic population extirpation and decimation immediately. That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. We find that the rate of population loss in terrestrial vertebrates is extremely high—even in “species of low concern.” In our sample, comprising nearly half of known vertebrate species, 32% (8,851/27,600) are decreasing; that is, they have decreased in population size and range. In the 177 mammals for which we have detailed data, all have lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range shrinkage). Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a “biological annihilation” to highlight the current magnitude of Earth’s ongoing sixth major extinction event.

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Acknowledgments

We thank John Harte for very helpful comments on the manuscript and Noé Torres, Giulia Santulli, and Jesús Pacheco for their help with data analyses. The Universidad Nacional Autónoma de México and Stanford University supported our work.

Supporting Information

Appendix (PDF)

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Information & Authors

Information

Published in

Go to Proceedings of the National Academy of Sciences
Go to Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences
Vol. 114 | No. 30
July 25, 2017
PubMed: 28696295

Classifications

Submission history

Published online: July 10, 2017
Published in issue: July 25, 2017

Keywords

  1. sixth mass extinction
  2. population declines
  3. population extinctions
  4. conservation
  5. ecosystem service

Acknowledgments

We thank John Harte for very helpful comments on the manuscript and Noé Torres, Giulia Santulli, and Jesús Pacheco for their help with data analyses. The Universidad Nacional Autónoma de México and Stanford University supported our work.

Authors

Affiliations

Gerardo Ceballos1 [email protected]
Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico;
Paul R. Ehrlich1 [email protected]
Department of Biology, Stanford University, Stanford, CA 94305
Rodolfo Dirzo
Department of Biology, Stanford University, Stanford, CA 94305

Notes

1
To whom correspondence may be addressed. Email: [email protected] or [email protected].
Author contributions: G.C., P.R.E., and R.D. designed research; G.C. and P.R.E. performed research; G.C., P.R.E., and R.D. contributed new reagents/analytic tools; G.C. analyzed data; and G.C., P.R.E., and R.D. wrote the paper.
Reviewers: T.E.L., George Mason University; and P.H.R., Missouri Botanical Garden.

Competing Interests

The authors declare no conflict of interest.

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    Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines
    Proceedings of the National Academy of Sciences
    • Vol. 114
    • No. 30
    • pp. 7731-E6270

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