Figure 6 in The beetles of the Lesser Antilles (Insecta, Coleoptera): diversity and distributions

Figure 6. Darlington (1957) proposed, as a "rule of thumb", that there exists, within a given region of relatively uniform climate, an orderly relation between the size of a sample area and the number of species found in that area, that there is a doubling of species numbers with each 10 times increase in island area. This was generalized as: (S = CAz) where C = 170. 5 andz = 0. 301 (MacArthur & Wilson, 1967) whichis shown as the regression line. Montserrat is the key reference datum point for anchoring this species-area regression line (Ivie et al, 2008a). This represents the hypothetical saturation number of species that might be expected to occur on an island of a designated area. Data points are for present day islands and island areas. The position of the data points for all the islands other than Montserrat fall under this line, which shows that more species would be expected on each island if it has the expected natural saturation number of species. The difference between the regression line and each data points suggests how many additional species might be expected with a complete knowledge of each island's fauna. These "undiscovered species" numbers are given in Table 2.