The history of the species–area relationship

The discovery of the species-area relationship, or SAR, cannot be attributed to a single person or time. Rather, and as true of the description and analysis of many patterns in nature, the story started with the realization of a phenomenon which, over time, and through many individual contributions, evolved into a developed theory. The history of the SAR thus concerns both the origins and the different forms and uses of SARs. We describe how the discovery of the phenomenon eventually led to the first proposed mathematical models of the relationship in the early twentieth century. This initiated the ongoing debates on the shape of the species–area curve, the factors that underpin SARs and the most appropriate model(s) for fitting. Alongside these debates, we review the history of the uses of the SAR and the central role it has played in the development of various fields within biogeography, from island biogeography through to conservation biogeography.