Science -- May and Stumpf 290 (5499): 2084

One of the earliest accomplishments of theoretical ecology was the discovery of a relationship between the number of species (of plants, birds, beetles, or whatever) on a given island and the area of that island (1). For example, a 10-fold increase in island area approximately doubles the number of species. This species-area relationship (SAR) is often used by conservation biologists to assess the long-term effects of the fragmentation of tropical forests, or other reductions in habitat area, upon species diversity (2). The SAR, as first enunciated by Mac Arthur and Wilson in their influential book Theory of Island Biogeography (1) and by others [see (3) and references therein], was phenomenological, based on observations. K