The map of biodiversity: From local to global scales

Speciesrichness is not homogeneous in space and it normally presentsdifferences when comparing among different sites. These differencesoften respond to gradients in one or several factors which createbiodiversity patterns in space and are scale-dependent. At a localscale, diversity patterns depend on the habitat size (species-arearelationship), the productivity, the environmental harshness, thefrequency and intensity of disturbance, or the regional speciespool. Regional diversity may be influenced by environmentalheterogeneity (increasing dissimilarity), although it could act alsoat smaller or larger spatial scales, and the connectivity amonghabitats. Finally, at a global scale, diversity patterns are foundwith the latitude, the altitude or the depth, although these factorsare surrogates or one or several environmental variables(productivity, area, isolation, orharshness).