Once again on the components of pairwise beta diversity

摘要

Presence-absence based beta diversity defined for pairs of sites may be partitioned into components following two different ways of thinking. Within the framework of Baselga (abbreviated hereafter as BAS), nestedness is crucial and dissimilarity is partitioned into replacement (turnover) and nestedness-resultant fractions. The method proposed by Podani and Schmera (POD), however, places emphasis on the mathematical additivity of components and divides dissimilarity into replacement and richness difference components. A recent comparison by Baselga and Leprieur (2015), on the example of the Jaccard family of indices, emphasizes the independence of replacement component from absolute richness difference and concludes that the replacement function of the BAS framework is the only true measure of species replacement. As a response to this study, we show here that 1) the sacrifice one must make for independence is that the components themselves are scaled differently and are not always comparable ecologically, 2) absolute (raw) replacement and richness difference are not independent, so that independence from the latter cannot be a fundamental criterion that a replacement measure should satisfy, 3) relativization applied in the POD framework is ecologically interpretable, leading to a meaningful conceptualization of species replacement, 4) the BAS and POD methods are linked through a generalized replacement function, 5) both the BAS and POD approaches may produce high correlations with environmental variables, whereas 6) the POD approach offers in many respects more illuminating demonstrations of the underlying changes of pattern than the graphs of Baselga and Leprieur for both artificial and actual fish distribution data. (C) 2016 Elsevier B.V. All rights reserved.