Preston's Bell Summary and Analysis

The relationship between the area of an ecological system and the number of species it supports is one that has been examined for many years, Quammen explains, with different conclusions. As it is related to island biogeography, the simplest explanation of the relationship is that the larger the island, the more species it can support.

This seems intuitive, Quammen writes, but it is more complicated than it first appears. He describes the observations of a biologist named Philip Darlington, who noticed that there seemed to be an approximate mathematical ratio between the area of an island and the number of species of related animals found on it. Darlington looked at amphibians and reptiles and noticed that an island of about four square miles had about 5 species from these groups. An island of ten times the size or forty square...