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The impact of alternative metrics on estimates of Extent of Occurrence for extinction risk assessment

Joppa, LN; Butchart, SHM; Hoffmann, M; Bachman, S; Akçakaya, HR; Moat, J; Bohm, M; ... Hughes, A; + view all (2016) The impact of alternative metrics on estimates of Extent of Occurrence for extinction risk assessment. Conservation Biology , 30 (2) pp. 362-370. 10.1111/cobi.12591. Green open access

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Abstract

Extent of Occurrence (EOO) is a key metric in assessing extinction risk using the IUCN Red List categories and criteria. However, the way in which EOO is estimated from maps of species’ distributions is inconsistent between assessments of different species, and between major taxonomic groups. It is often estimated from the area of mapped distribution, but these maps often exclude areas of unsuitable habitat in idiosyncratic ways and are not created at the same spatial resolutions. We assessed the impact on extinction risk categories of applying different methods for estimating EOO for 21,763 species of mammals, birds and amphibians. Overall, we found that the percentage of threatened species requiring downlisting to a lower category of threat, taking into account other Red List criteria under which they qualified, spanned 11-13% for all species combined (14-15% for mammals, 7-8% for birds and 12-15% for amphibians) depending on the method used. Extrapolating from birds for missing data for amphibians and mammals suggests that 14% of threatened and Near Threatened species potentially require downlisting using a Minimum Convex Polygon (MCP) approach, as now recommended by IUCN, with other metrics (such as alpha hull) having marginally smaller impacts. We conclude that uniformly applying the MCP approach will potentially lead to a one-time downlisting of hundreds of species, but ultimately ensure consistency across assessments and realign the calculation of EOO with the theoretical basis upon which the metric was founded.

Type: Article
Title: The impact of alternative metrics on estimates of Extent of Occurrence for extinction risk assessment
Open access status: An open access version is available from UCL Discovery
DOI: 10.1111/cobi.12591
Publisher version: http://dx.doi.org/10.1111/cobi.12591
Language: English
Additional information: This is the peer reviewed version of the following article: Joppa, LN; Butchart, SHM; Hoffmann, M; Bachman, S; Akçakaya, HR; Moat, J; Bohm, M; (2015) The impact of alternative metrics on estimates of Extent of Occurrence for extinction risk assessment. Conservation Biology, which has been published in final form at: http://dx.doi.org/10.1111/cobi.12591. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Keywords: Distribution maps; IUCN Red List; threatened; amenazado; Lista Roja UICN; mapas de distribución
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Genetics, Evolution and Environment
URI: https://discovery.ucl.ac.uk/id/eprint/1469975
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