Datasets
We analyzed data available in the FragSAD open dataset compilation (Chase et al. 2019). FragSAD includes 117 metacommunities defined by counts of species recorded in several habitat patches of (usually) known sizes. We excluded from FragSAD (i) datasets containing an insufficient number of patches for SLOSS comparisons, i.e., ≤ 2 patches; (ii) patches for which area was missing or roughly imputed, because SLOSS comparisons are area-based; and (iii) patches that were larger than 50% of the total area sampled in a dataset, because these patches cannot be compared to an equal total area made of smaller patches. Given that the studies recorded in FragSAD were originally designed to compare metacommunities across gradients of fragment sizes (Chase et al.2019), we assumed that the patches within each dataset were within a given landscape and were of meaningful sizes for the taxa sampled – a corollary being that “large” and “small” patches vary depending on the system studied.