How Accurate are Our Estimates of Assemblage Similarity?

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Estimating assemblage similarity is the starting point of multivariate analyses. Beta diversity is also often assessed based on this estimation. However, the accuracy of these estimates is unknown because only a proportion of the species is normally sampled. Statistical methods were recently proposed to predict the “true” similarity between assemblages, but their effectiveness and limitations are poorly understood. In this study, I simulated three groups of assemblages: 1) highly diverse ones with similar species-occurrence distributions (SODs); 2) a succession series with increasing richness and changing SODs; and 3) local assemblages containing random subsets of similar size from the regional species pool and with different SODs. I tested Chao’s versions of the Jaccard and Sørensen indices based on incident frequencies against the standard estimates and the true values. I found that 1) the two indices were moderately underestimated among the Group-1 assemblages and Chao’s methods reduced the bias; 2) both indices could be over- or under-estimated for assemblages in Group 2 or 3, frequently severely so, and Chao’s methods failed to reduce the bias or even increased it; and 3) accuracy improved with increasing sampling effort. These results highlight the challenges in comparing disparate assemblages and the importance of adequately sampling.
Original languageEnglish (US)
Title of host publication56th Annual Meeting of the North American Benthological Society (NABS 2008), Salt Lake City, Utah (USA), 25-30 May 2008
StatePublished - 2008


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