Spatial scaling of extinction rates: Theory and data reveal nonlinearity and a major upscaling and downscaling challenge
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Authors
Biodiversity loss is a key component of biodiversity change and can impact ecosystem services. However, estimation of the loss has focused mostly on per‐species extinction rates measured over a limited number of spatial scales, with little theory linking small‐scale extirpations to global extinctions. Here, we provide such a link by introducing the relationship between area and the number of extinctions (number of extinctions–area relationship; NxAR) and between area and the proportion of extinct species (proportion of extinctions–area relationship; PxAR). Unlike static patterns, such as the species–area relationship, NxAR and PxAR represent spatial scaling of a dynamic process. We show theoretical and empirical forms of these relationships and we discuss their role in perception and estimation of the current extinction crisis.
Location
U.S.A., Europe, Czech Republic and Barro Colorado Island (Panama).
Time period
1500–2009.
Major taxa studied
Vascular plants, birds, butterflies and trees.
Methods
We derived the expected forms of NxAR and PxAR from several theoretical frameworks, including the theory of island biogeography, neutral models and species–area relationships. We constructed NxAR and PxAR from five empirical datasets collected over a range of spatial and temporal scales.
Results
Although increasing PxAR is theoretically possible, empirical data generally support a decreasing PxAR; the proportion of extinct species decreases with area. In contrast, both theory and data revealed complex relationships between numbers of extinctions and area (NxAR), including nonlinear, unimodal and U‐shaped relationships, depending on region, taxon and temporal scale.
Main conclusions
The wealth of forms of NxAR and PxAR explains why biodiversity change appears scale dependent. Furthermore, the complex scale dependence of NxAR and PxAR means that global extinctions indicate little about local extirpations, and vice versa. Hence, effort should be made to understand and report extinction rates as a scale‐dependent problem. In this effort, estimation of scaling relationships such as NxAR and PxAR should be central.
| Original language | English |
|---|---|
| Journal | Global Ecology and Biogeography |
| Volume | 27 |
| Issue number | 1 |
| Pages (from-to) | 2-13 |
| Number of pages | 12 |
| ISSN | 1466-822X |
| DOIs | |
| Publication status | Published - 01.01.2018 |
| Externally published | Yes |
Bibliographical note
Funding Information:
We are grateful to the handling editor Allen Hurlbert, to two anonymous referees and to A. Berger, C. Lawson and C. Meyer for helpful comments. The BCI forest dynamics research project was founded by S. P. Hubbell and R. B. Foster and is now managed by R. Condit, S. Lao and R. Perez under the Center for Tropical Forest Science and the Smithsonian tropical Research in Panama. Numerous organizations have provided funding, principally the U.S. National Science Foundation, and hundreds of field workers have contributed. All authors acknowledge funding of iDiv via the German Research Foundation (DFG FZT 118), while P.K., J.S.C. and M.W. acknowledge specifically funding through sDiv, the synthesis centre of iDiv.
Publisher Copyright:
© 2017 The Authors. Global Ecology and Biogeography Published by John Wiley & Sons Ltd
- Gender and Diversity - Anthropocene, continental, grain, habitat loss, local, mass extinction, MAUP, metapopulation, patch, resolution
Research areas
- SDG 15 - Life on Land
- SDG 17 - Partnerships for the Goals
Sustainable Development Goals
- Ecology, Evolution, Behavior and Systematics
- Ecology
- Global and Planetary Change