Reply to Kalinkat et al.: Smallest terrestrial vertebrates are highly imperiled

November 9, 2017
114 (48) E10265
Research Article
Extinction risk is most acute for the world’s largest and smallest vertebrates
William J. Ripple, Christopher Wolf [...] Douglas J. McCauley
Letter
Exceptional body size–extinction risk relations shed new light on the freshwater biodiversity crisis
Gregor Kalinkat, Sonja C. Jähnig, Jonathan M. Jeschke
Kalinkat et al. (1) discuss the biodiversity crisis in their reply to our article “Extinction risk is most acute for the world’s largest and smallest vertebrates” (2). We agree with Kalinkat et al. (1) that small freshwater species tend to have elevated extinction risk, an issue that we highlight in our paper (2). Specifically, 41% (36 of 87) of freshwater vertebrate species with body masses ≤ 0.001 kg are listed as threatened compared with 29% (1,578 of 5,428) threatened for all freshwater vertebrate species. However, small vertebrates that use terrestrial habitats exclusively or in combination with freshwater habitats also have a greatly elevated risk of extinction (figure S3 in ref. 2). Indeed, our data show that 59% (76 of 128) of terrestrial vertebrate species with body masses ≤ 0.001 kg are threatened compared with 16% (1,965 of 12,015) for all terrestrial vertebrate species. Similarly, 35% (36 of 102) of the vertebrates with body mass ≤ 0.001 kg that use both terrestrial and freshwater habitats are threatened compared with 19% (527 of 2,842) threatened for all terrestrial/freshwater vertebrates.
Interestingly, the smallest marine vertebrates have relatively low extinction risk (figure S3 in ref. 2), perhaps because, relative to land, humans have thus far had less severe impacts on the quality of their habitats, and likely because small marine vertebrates have larger ranges, on average, than small freshwater or terrestrial vertebrates. These marine taxa could face greater extinction risk in the future, however, due to intensified harvest of small marine vertebrates [e.g., forage fish (3)] and the acceleration of climate change and associated ocean warming and acidification (4). In contrast, the smallest bony fishes, amphibians, and reptiles have elevated extinction risk (figure S3 in ref. 2). Notably, all of the smallest amphibians (≤0.001 kg body mass; mostly frogs and salamanders, n = 200) are linked to terrestrial or terrestrial/freshwater habitat. Similarly, all of the smallest reptiles (≤0.001 kg body mass; mostly geckos, n = 30) are terrestrial inhabitants. Unfortunately, the plights of both the smallest freshwater and smallest terrestrial species have received relatively little research attention compared with that of the large-bodied species (5) (figure S5 in ref. 2). These terrestrial minifauna need our immediate scientific and conservation attention and, yes, freshwater species do as well.

References

1
G Kalinkat, SC Jähnig, JM Jeschke, Exceptional body size–extinction risk relations shed new light on the freshwater biodiversity crisis. Proc Natl Acad Sci USA 114, E10263–E10264 (2017).
2
WJ Ripple, et al., Extinction risk is most acute for the world’s largest and smallest vertebrates. Proc Natl Acad Sci USA 114, 10678–10683 (2017).
3
ML Pinsky, OP Jensen, D Ricard, SR Palumbi, Unexpected patterns of fisheries collapse in the world’s oceans. Proc Natl Acad Sci USA 108, 8317–8322 (2011).
4
AL Perry, PJ Low, JR Ellis, JD Reynolds, Climate change and distribution shifts in marine fishes. Science 308, 1912–1915 (2005).
5
SF Carrizo, et al., Freshwater megafauna: Flagships for freshwater biodiversity under threat. Bioscience 67, 919–927 (2017).

Information & Authors

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Published in

Go to Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences
Vol. 114 | No. 48
November 28, 2017
PubMed: 29122936

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Submission history

Published online: November 9, 2017
Published in issue: November 28, 2017

Authors

Affiliations

William J. Ripple1 [email protected]
Global Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331;
Christopher Wolf
Global Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331;
Thomas M. Newsome
Global Trophic Cascades Program, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR 97331;
School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Geelong, VIC 3125, Australia;
School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia;
School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195;
Michael Hoffmann
International Union for Conservation of Nature, Species Survival Commission, Gland 1196, Switzerland;
Conservation Programmes, Zoological Society of London, London NW1 4RY, United Kingdom;
Aaron J. Wirsing
School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195;
Douglas J. McCauley
Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106

Notes

1
To whom correspondence should be addressed. Email: [email protected].
Author contributions: W.J.R., C.W., T.M.N., M.H., A.J.W., and D.J.M. wrote the paper.

Competing Interests

The authors declare no conflict of interest.

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    Reply to Kalinkat et al.: Smallest terrestrial vertebrates are highly imperiled
    Proceedings of the National Academy of Sciences
    • Vol. 114
    • No. 48
    • pp. 12627-E10507

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