Abstract
Species richness and ecological uniqueness (defined as local contributions of sites to beta diversity of a region) constitute two crucial components of biodiversity. Understanding the relationship between these two components is critical for effective conservation planning, yet global patterns and underlying drivers remain largely controversial. Here, we conduct a comprehensive global meta-analysis to investigate the patterns of the species richness-ecological uniqueness relationship across taxa groups and to evaluate the relative importance of four ecological hypotheses in driving this relationship (i.e. species pool, dispersal limitation, environmental filtering and spatial grain size). We find that negative richness-uniqueness relationships are prevalent across different taxa groups (e.g. terrestrial plants, freshwater macroinvertebrates, birds, and fishes), and such negative association is robust to different data types including presence absence and abundance data. Notably, relationships based on presence-absence data are primarily predicted by species pool attributes (i.e. the proportion of rare species and gamma diversity), whereas abundance-based relationships are more strongly associated with dispersal limitation. In summary, these findings reveal consistent global patterns and mechanistic underpinnings of the richness-uniqueness relationship, offering key insights for biodiversity conservation. We recommend that conservation strategies should prioritize both species-rich and ecologically unique communities to maximize biodiversity protection globally.
Data availability
The Supporting data and three appendices (Appendix 1, Appendix 2 and Appendix 3) that support the findings of this study are available in Figshare at https://doi.org/10.6084/m9.figshare.2927004894. The reference list of included and excluded studies is also provided as Supplementary Data 1. Source data are provided in this paper.
Code availability
R code that supports the findings of this study is available in Figshare at https://doi.org/10.6084/m9.figshare.2927004894.
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Acknowledgements
This work was supported by the National Natural Science Foundation of China (32525041), the CAS (Chinese Academy of Sciences) Project for Young Scientists in Basic Research (YSBR-108), and Liaoning Revitalization Talents Program (XLYC2402003). J.A.M. was supported by grants from the U.S. National Science Foundation (DEB 2240431) and the Seeding Projects for Enabling Excellence and Distinction (SPEED) program at Washington University in St. Louis.
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Conceptualization: X.W. and Y.C. Methodology (extraction): Y.C. Methodology (statistical analysis): Y.C. and J.S. Visualization: Y.C. Writing—original draft: Y.C. and X.W. Writing—review, and editing: J.S., J.A.M., Z.M., J.Y., and X.W.
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Chen, Y., Soininen, J., Myers, J.A. et al. Meta-analysis reveals widespread negative associations between species richness and ecological uniqueness.
Nat Commun (2026). https://doi.org/10.1038/s41467-026-70886-2
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DOI: https://doi.org/10.1038/s41467-026-70886-2
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