, Volume 119, Issue 2, pp 256–264

Nested species subsets, gaps, and discrepancy

  • Richard A. Brualdi
  • James G. Sanderson

DOI: 10.1007/s004420050784

Cite this article as:
Brualdi, R. & Sanderson, J. Oecologia (1999) 119: 256. doi:10.1007/s004420050784


The nested-subset hypothesis of Patterson and Atmar states that species composition on islands with less species richness is a proper subset of those on islands with greater species richness. The sum of species absences, referred to as gaps, was suggested as a metric for nestedness, and null models have been used to test whether or not island species exhibited nestedness. Simberloff and Martin stated that finding examples of non-nested faunas was difficult. We revisit previous analyses of nested faunas and introduce a new metric we call “discrepancy” which we recommend as a measure for nestedness. We also recommend that the sample spaces conserve both row sums (number of species per site) and column sums (number of sites per species) derived from the incidence matrix. We compare our results to previous analyses.

Key words Community structureNestednessNull matrixGapsDiscrepancies

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Richard A. Brualdi
    • 1
  • James G. Sanderson
    • 2
  1. 1.Mathematics Department, University of Wisconsin, Madison, WI 53706-1313, USAUS
  2. 2.Department of Wildlife Ecology and Conservation, PO Box 110430, University of Florida, Gainesville, FL 32611-0430, USAUS