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  • Article
    Species–area relationships always overestimate extinction rates from habitat loss : comment
    (Ecological Society of America, 2013-03) Axelsen, Jacob Bock ; Roll, Uri ; Stone, Lewi ; Solow, Andrew R.
    The species–area relationship summarizes the relationship between the average number of species in a region and its area. This relationship provides a basis for predicting the loss of species associated with loss of habitat (e.g., Pimm and Raven 2000). The approach involves two steps. First, as discussed in more detail below, the species–area relationship is used to predict the number of species that are endemic to the habitat at risk based on its area. Second, these endemic species are assumed to become extinct should this habitat be lost. In a controversial paper, He and Hubbell (2011) argued that the way in which the species–area relationship is used to predict the number of endemic species is incorrect when individual organisms are aggregated in space and argued that this explains a discrepancy between predicted and observed extinction rates associated with habitat loss. The controversy surrounding the paper focused primarily on the second part of their argument (Brooks 2011, Evans et al. 2011, He and Hubbell 2012, Pereira et al. 2012, Thomas and Williamson 2012). Here, we focus on the details underlying the first part.
  • Dataset
    Testing for a shift in a species boundary
    ( 2013-12-09) Solow, Andrew R. ; Beet, Andrew R. ; Roll, Uri ; Stone, Lewi
    One predicted impact of climate change is a poleward shift in the boundaries of species ranges. Existing methods for identifying such a boundary shift based on changes in the observed pattern of occupancy within a grid of cells are sensitive to changes in the overall rate of sightings and their latitudinal distribution that are unconnected to a boundary shift. A formal test for a boundary shift is described that allows for such changes. The test is applied to detect northward shifts in the northern boundary of the Essex skipper butterfly and the European goldfinch in Great Britain. A shift is detected in the latter case but not in the former. Results from a simulation study are presented showing that the test performs well.