ON THE IMPLICATIONS OF SPECIES-AREA RELATIONSHIPS FOR ENDEMISM, SPATIAL TURNOVER, AND FOOD-WEB PATTERNS

Consequences of species-area relationships (SARs) of the form S = cA(z ) are derived; One consequence is an endemics-area relationship (EAR); it is of the same power-law form as the SAR but with an exponent z' t hat is a function only of z and that always exceeds unity. An explicit formula is derived for the dependence of species turnover in space on census plot size, interplot distance, and the SAR exponent z; this fo rmula can be used to determine z over spatial scales that are too larg e to permit direct estimate of z by censusing of nested patches. The a real dependence of link-species patterns observed in food webs is also examined; SARs are shown to imply the approximate, but not exact, are a-independence of link-species relationships of the form L = kS(y), wh ere L is the number-of trophic links and y less than or equal to 2. A relationship between the average range of species in a habitat patch a nd the exponent z is also derived, leading to the result that average range is a decreasing function of both patch area and z.