Abstract

Nestedness is a pattern whereby species-poor assemblages are composed of subsets of the species occurring in richer assemblages. One of the most commonly used measures of the degree of nestedness for presence-absence matrices is the 'discrepancy' metric. A hitherto neglected property of that metric is that it may take several values for a given site-by-species matrix in the presence of ties in the marginal totals. This complicates the quantification of nestedness for the observed presence-absence matrix, as well as the assessment of statistical significance, which is typically achieved through Monte Carlo simulations. A solution to the problem is to calculate the minimum discrepancy using a modified algorithm involving permutations of columns with tied totals.

Keywords

Ecological communities; Nested subsets; Nestedness metrics; Presence-absence matrices; Species composition

Published in

Community Ecology
2009, Volume: 10, number: 2, pages: 141-145

SLU Authors

• Roberge, Jean-Michel

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    
  • University of Jyväskylä

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1556/ComEc.10.2009.2.1

Permanent link to this page (URI)

https://res.slu.se/id/publ/28584