Biodiversity and Conservation

, Volume 24, Issue 11, pp 2877–2882 | Cite as

‘Sum of inverse range-sizes’ (SIR), a biodiversity metric with many names and interpretations

  • Greg R. Guerin
  • Andrew J. Lowe


Range restriction is an important measure of species rarity that is also interpreted as endemism. A simple biodiversity metric, the sum of inverse range-sizes (‘SIR’) for species within a sampling unit is useful for conservation planning but has multiple names and applications: for example, to highlight areas of high biodiversity and biological uniqueness (the hotspots problem, e.g. ‘weighted endemism’) and as a range proportion-explicit metric for calculating complementarity in reserve selection (the representation problem, e.g. ‘rarity-weighted richness’). This paper outlines the development, implementation and duplication of SIR. We propose that terminology for equivalent metrics can be unified if:- ‘SIR’ refers to them generally; those based on site or grid cell occupancy, or area of occupancy, are referred to specifically as ‘range-rarity richness’); while those aimed at measuring endemism based on extent of occurrence are referred to specifically as ‘georeferenced weighted endemism’. The phylogenetic equivalents would then be ‘phylogenetic range-rarity’ and ‘georeferenced phylogenetic endemism’, respectively.


Area of occupancy Extent of occurrence Range rarity Rarity-weighted richness Species richness Weighted endemism 



We thank the Terrestrial Ecosystem Research Network and the South Australian Department of Environment, Water and Natural Resources.


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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  1. 1.Terrestrial Ecosystem Research Network, Adelaide-node, School of Biological Sciences, The Environment InstituteUniversity of AdelaideAdelaideAustralia
  2. 2.Science, Monitoring and Knowledge, Department of EnvironmentWater and Natural ResourcesAdelaideAustralia

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