Abstract
Understanding the drivers of species coexistence is an important objective in ecology. Yet, the multitude of methods to study coexistence hampers cross-community comparisons. Here, we standardized niche and fitness differences (i.e how species limit themselves compared to others and their competitive ability, respectively) across 1018 species pairs to investigate species coexistence across ecological groups and methodological settings (experimental setup, natural co-occurrence, population model used, and growth method). We find that, first, coexistence is driven by large niche differences, not by small fitness differences. Second, species group into clear clusters of coexisting and non-coexisting species along the niche axis. Finally, these clusters are not driven by ecological or methodological settings. This suggests differences between coexisting and non-coexisting communities transcending those measured in our empirical systems. Overall, our results show that species coexistence is mainly influenced by mechanisms acting on niche differences.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
juerg.spaak{at}gmail.com
javier.jarillodiaz{at}unamur.be
frederik.delaender{at}unamur.be
Statement of authorship: LB and JS designed the collection of data. LB gathered the data, with help from all authors. JS computed the N and F. LB analyzed the data with inputs from JS and FDL. Js performed the clustering. JJ performed the meta-analysis and odd-ratio analysis. LB and JS wrote the first draft of the manuscript, and all authors contributed substantially to revisions.
Data accessibility statement: Code is available on Github https://github.com/Buchel9844/Meta-analysis_NFD.
Two main concerns were particularly addressed: (1) the grouping of empirical communities into different ecological groups (Phytoplankton, Annual plants, Perennial plants and microbes); (2) our focus on both processes and outcomes and whether these are equivalent. To address these two concerns we have changed the manuscript in two substantial ways: 1.We do not group the empirical data into predefined groups, but rather let an automated clustering algorithm decide how many different groups there are and how these groups are defined. While we discovered that these groups exist, they turn out to not represent distinct ecological groups. 2.We have reduced the emphasis on outcomes and processes, not necessarily because we think they are tautological, but because we believe they are of secondary importance to our current manuscript.
