A positive relationship between local abundance and regional occupancy is almost inevitable (but not all positive relationships are the same).

Abstract

Recent attempts to examine the role of different mechanisms in generating a positive abundance-occupancy relationship failed to properly distinguish between Brown's (1984) sampling artefact, and the form of relationship to be expected from a random distribution of individuals. Because random distributions generate a positive relationship, one can never predict that removing the influence of some or all of the mechanisms will lead to 'no relationship'. In considering how the spatial aggregation of individuals might influence the form of the abundance-occupancy relationship it is demonstrated that curvilinear and triangular relationships are expected, and that correlation coefficients and linear regression statistics are unlikely to be sensitive to the addition and removal of mechanisms. Examining distributional data with alternative indices of spatial structure may lead to a more intuitive understanding of how different mechanisms influence the form of abundance-occupancy relationships.