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.
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.