BIOGEOGRAPHICAL RESEMBLANCE BETWEEN AREAS

A program, written in the computer language BASIC, is described that calculates by various formulas the degree of biogeographical resemblance between areas. The various formulas are described, and the proper machine instructions for each are indicated. In their recent analysis of the distributional patterns of North American mammals, Hagmeier and Stults (1964:131) summarized the various formulas that have been proposed by biogeographers for use in the analysis of the degree of relationship between two areas. They chose three of these formulas to use in their calculations, and listed four more that had been suggested and used by various authors. The decision by Hagmeier and Stults to use the "Coefficient of Community" and the "Simpson Coefficient" was based on the simplicity of the formulas and the ease with which they could be calculated. Several of the other formulas used, such as the "Resemblance Equation" of Preston (1962), include logarithms, square roots, or consultation of tables, and the increased amount of effort involved has interfered with their use by biogeographers. Since most of the formulas were introduced as attempts to eliminate difficulties resulting from different sample size, it seems likely that a worker might wish to see what results all would give with his data. In the past, however, biogeographers have usually chosen one formula, because if the number of localities involved is very large, the amount of time devoted to the calcula