A NOTE ON THE ANALYSIS OF SPECIES COOCCURRENCES

The analysis of records of species occurrences on islands in an attemp t to detect interactions between species has been an area of controver sy in recent years in terms of the validity of some of the statistical methods used. In this note I make two contributions to the continuing debate. First, I advocate a generalized Monte Carlo testing procedure because this is easy to implement, is computationally efficient, and has guaranteed properties when the null hypothesis of no species inter actions is correct. Second, I propose a test statistic that can be dec omposed into a component for each individual species, and I demonstrat e how this makes it possible to isolate species with unusual patterns of co-occurrence with other species, even after an allowance for multi ple testing is made.