The biogeography of ecoregions: Descriptive power across regions and taxa

Aim Biomes, biogeographical realms and ecoregions have become central concepts of biotic organization and biodiversity research. Recent data-intensive analysis has shown that, while ecoregions do delineate biotic communities, how distinct they are from one another varies considerably across regions and taxa. Given their central importance to global models of the earth system and to the development of conservation plans, it is key to understand in what regions, and for which taxa, ecoregion classification schemes best describe the underlying variability in biological communities. Location Global. Taxa Plants, animals, fungi. Methods In this paper, we integrate ecoregion maps with data on spatially continuous changes in environmental conditions, biodiversity and species traits to quantify the descriptive power of ecoregions around the globe. Capitalizing on the troves of newly available global biodiversity data, we model the abiotic and biotic factors that describe how distinct ecoregions are from one another. Results From an abiotic perspective, we report compelling evidence that, first, ecoregions are more distinct in tropical zones with higher temperatures, less temperature seasonality and greater rainfall seasonality. Second, we also find that ecoregions are more distinct in regions with steeper slopes. From a biotic perspective, we find that ecoregions tend to be more distinct for reptiles and amphibians than they are for mammals or birds. Likewise, ecoregions tend to be more distinct for smaller-bodied species and, to a lesser extent, species at lower trophic levels. Main conclusions While ecoregion-based conservation planning can provide a crucial tool for developing holistic conservation interventions, we show here that the ability to capture and describe communities is not uniform across regions or taxa. In particular, ecoregions tend to best describe communities of small-bodied species, less vagile and tropical taxa that are typically underrepresented in the scientific literature. While ecoregion classification schemes will continue to provide invaluable conservation guidance, we must think critically about when an ecoregional approach is best suited to informing management.