variation in the strength and breadth of transition zones between biotic
New approaches to measuring spatial turnover in species among neighbourhoods of adjacent grid cells on maps can be used to locate many of the boundaries detected by classification (see above) between different faunas. But in addition, these turnover measures allow exploration of variation in the strength and breadth of the transition zones along the biogeographic boundaries (high scores are not constrained to occur together in lines, and need not completely encircle biotic regions). The example shows the application of one of these measures ('beta-3', based on Whittaker's measure of beta diversity) to the same bumble bee data (ref 9). Orange cells occur in neighbourhoods of high species turnover (i.e. the transition zones) and blue cells are in neighbourhoods of low species turnover (below):
Current work is exploring this approach at finer spatial scales and using a broad range of pattern measures. This work relates not only to questions in academic biogeography, but also has potential applications in conservation biology and research into environmental change through changing ecotones.