Biodiversity Scaling on a Continuous Plane: Geometric Underpinnings of the Nested Species-Area Relationship
Abstract
The species-area relationship (SAR) is considered to be one of the most universal ecological patterns. Indeed, the notion that the number of species recorded within a region should increase as the area of the region increases seems intuitive.
No study of diversity patterns in space or time makes sense without accounting for this simple fact (Rosenzweig, 1995). To account for the increase in species richness with area, one needs to know the SAR's properties (e.g. its shape and slope) and the factors that affect them.
The important component of this understanding is that the drivers of the SAR can be seen as being organized across two hierarchical levels: the geometric and the biological. Each SAR is shaped by biological drivers within the constraints given by geometric rules.
Geometry, unlike biology, cannot directly determine actual species richness, but it determines the constraints for the differences in species richness among sites and scales. Geometric rules provide links between the SAR and other macroecological patterns, namely the frequency distribution of species abundances (species abundance distribution, hereafter SAD), species spatial turnover (beta diversity) and, in particular, the spatial distribution patterns of individual species.
In the chapter we summarize geometric drivers of the SAR.