Estimating the normal background rate of species extinction.

De Vos, Jurriaan M

Joppa, Lucas N

Gittleman, John L

Stephens, Patrick R

Pimm, Stuart L

2021-08-02T18:38:49Z

2021-08-02T18:38:49Z

2015-04

2021-08-02T18:38:47Z

A key measure of humanity's global impact is by how much it has increased species extinction rates. Familiar statements are that these are 100-1000 times pre-human or background extinction levels. Estimating recent rates is straightforward, but establishing a background rate for comparison is not. Previous researchers chose an approximate benchmark of 1 extinction per million species per year (E/MSY). We explored disparate lines of evidence that suggest a substantially lower estimate. Fossil data yield direct estimates of extinction rates, but they are temporally coarse, mostly limited to marine hard-bodied taxa, and generally involve genera not species. Based on these data, typical background loss is 0.01 genera per million genera per year. Molecular phylogenies are available for more taxa and ecosystems, but it is debated whether they can be used to estimate separately speciation and extinction rates. We selected data to address known concerns and used them to determine median extinction estimates from statistical distributions of probable values for terrestrial plants and animals. We then created simulations to explore effects of violating model assumptions. Finally, we compiled estimates of diversification-the difference between speciation and extinction rates for different taxa. Median estimates of extinction rates ranged from 0.023 to 0.135 E/MSY. Simulation results suggested over- and under-estimation of extinction from individual phylogenies partially canceled each other out when large sets of phylogenies were analyzed. There was no evidence for recent and widespread pre-human overall declines in diversity. This implies that average extinction rates are less than average diversification rates. Median diversification rates were 0.05-0.2 new species per million species per year. On the basis of these results, we concluded that typical rates of background extinction may be closer to 0.1 E/MSY. Thus, current extinction rates are 1,000 times higher than natural background rates of extinction and future rates are likely to be 10,000 times higher.

0888-8892

1523-1739

https://hdl.handle.net/10161/23550

eng

Wiley

Conservation biology : the journal of the Society for Conservation Biology

10.1111/cobi.12380

Animals

Chordata

Invertebrates

Plants

Conservation of Natural Resources

Phylogeny

Models, Biological

Fossils

Computer Simulation

Extinction, Biological

Biological Evolution

Estimating the normal background rate of species extinction.

Journal article

Pimm, Stuart L|0000-0003-4206-2456

452

462

2

Nicholas School of the Environment

Environmental Sciences and Policy

Duke Science & Society

Duke

Initiatives

Institutes and Provost's Academic Units

Published

29