Sir

According to H. J. Fisher in Correspondence1, the scientific concerns of the recently emerged discipline of macroecology are a subset of those of biogeography, and hence the former is simply a sub-discipline of the latter. As evidence, Fisher observes that some macroecologists have written books on biogeography. We believe that his view is mistaken.

Biogeography is the science that attempts to document and understand spatial patterns of biodiversity2. Macroecology is a way of studying relationships between organisms and their environment that involves characterizing and explaining statistical patterns of abundance, distribution and diversity — exploring the domain where ecology, biogeography, palaeontology and macroevolution come together3. Some overlap of interests between macroecology and biogeography has always been acknowledged (as has too, for example, between ecology and evolution), but in definitions that make clear their separate aims and identities.

Fisher's point that the same scientists have written on biogeography and macroecology in fact highlights precisely the fact that they recognize the distinction.

Differences between macroecology and biogeography in scope and aim are apparent from the subjects covered in the macroecology symposium that prompted Fisher's comments. These included the ecological and evolutionary implications of the scaling of vascular networks; intraspecific optimization as a cause of interspecific allometry; the relationship between life history, population dynamics and extinction risk; neutral models of the assembly of local ecological communities from regional metacommunities; whether speciation rates are influenced by body size; and whether diversification is driven by key innovations (see ref. 4).

All these issues in macroecology may help us to understand the distribution and diversity of life on Earth, and so they may inform a range of disciplines that includes biogeography. But they are not biogeography.