On the relationship between species diversity and range size

Aim What factors may affect species range sizes remains a central question in ecology and biogeography. Particularly, whether and how species richness may regulate average species range size remains largely elusive. Here, we explore the relationship between species diversity and species range size at a global extent and discuss its implications and significance for ecology and management. Location Worldwide. Taxon Plants and various groups of animals. Methods We used published data on plant richness and range size from around the world and synthesized related literature to assess the richness–range size relationships. We used paired t-tests and spatial autoregressive models in data analyses. We conducted a series of partial regressions to partition the variation in species ranges explained by paired independent variables (i.e. species richness versus latitude, species richness versus temperature or species richness versus temperature variability). Results A negative relationship between species diversity (richness) and species range size is nearly ubiquitous. In most cases, species diversity was a better predictor for species range size than latitude, temperature or temperature variability. Main conclusions The diversity predictor works well for different taxonomic groups, regions, continents, and for both terrestrial and marine biomes. High species diversity could imply stronger species interactions such as competition which limit the range sizes of constituent species. A nearly universal negative richness–range size relationship thus has significant implications for species invasion biology and conservation.