Abstract
Biogeographical regions (geographically distinct assemblages of species and communities) constitute a cornerstone for ecology, biogeography, evolution and conservation biology. Species turnover measures are often used to quantify spatial biodiversity patterns, but algorithms based on similarity can be sensitive to common sampling biases in species distribution data. Here we apply a community detection approach from network theory that incorporates complex, higher order presence-absence patterns. We demonstrate the performance of the method by applying it to all amphibian species in the world (c. 6,100 species), all vascular plant species of the USA (c. 17,600), and a hypothetical dataset containing a zone of biotic transition. In comparison with current methods, our approach tackles the challenges posed by transition zones and succeeds in retrieving a larger number of commonly recognised biogeographical regions. This method can be applied to generate objective, data derived identification and delimitation of the world’s biogeographical regions.
Highlights
Biogeographical regions constitute a cornerstone for ecology, biogeography, evolution and conservation biology
Bioregions may be considered analogous to biodiversity hotspots, a concept based on species richness, endemicity and threat, which has received enormous attention in ecology, biogeography and conservation in the last decades[23]
Our analysis identified 10 major bioregions and 55 smaller biogeographical regions as the optimal representation of the full amphibian data set (Fig. 3a)
Summary
Biogeographical regions (geographically distinct assemblages of species and communities) constitute a cornerstone for ecology, biogeography, evolution and conservation biology. One common feature in most schemes of bioregionalization (the scientific discipline that deals with identifying, delimiting and naming biogeographical regions) is an internally implied hierarchy This is for instance evident in the terrestrial classification system of Olson et al.[12], which is the one adopted by the World Wide Fund for Nature (WWF) and recognizes eight realms, nesting 14 biomes which in turn contain 867 ecoregions. Ecoregions are defined as ‘relatively large units of land containing a distinct assemblage of natural communities and species, with boundaries that approximate the original extent of natural communities prior to major land use change’ and reflecting ‘distributions of a broad range of fauna and flora across the entire planet’ This and other classification systems widely used in biogeography This and other classification systems widely used in biogeography (for an example see ref. 8) include a key taxonomic component, contrasting with purely abiotic approaches such as the Koppen–Geiger Climate Classification[29], which in its latest update[30] is based solely on ranges of temperature, precipitation and their distribution over the year
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