Better explicating the strengths and shortcomings of these models will help refine projections and improve transparency in the years ahead.
Image credit: Witsawat.S.
Edited by Nils Chr. Stenseth, University of Oslo, Oslo, Norway, and approved December 30, 2020 (received for review March 26, 2020)
Significance
Biodiversity is driven by complex associations among species, but ecologists often look only at competitive or facilitative interactions either independently or only for few species at a time. Using a large dataset of mountain ecosystems encompassing more than 2,000 species across the globe, we analyze the prevalence and importance of both positive and negative associations among plants. Our findings indicate that facilitation and competition between plant species must be studied together in order to explain biodiversity change.
Abstract
Biological diversity depends on multiple, cooccurring ecological interactions. However, most studies focus on one interaction type at a time, leaving community ecologists unsure of how positive and negative associations among species combine to influence biodiversity patterns. Using surveys of plant populations in alpine communities worldwide, we explore patterns of positive and negative associations among triads of species (modules) and their relationship to local biodiversity. Three modules, each incorporating both positive and negative associations, were overrepresented, thus acting as "network motifs." Furthermore, the overrepresentation of these network motifs is positively linked to species diversity globally. A theoretical model illustrates that these network motifs, based on competition between facilitated species or facilitation between inferior competitors, increase local persistence. Our findings suggest that the interplay of competition and facilitation is crucial for maintaining biodiversity.
- biodiversity change
- community ecology
- ecological networks
- mountain ecosystems
- plant interaction networks
Footnotes
- ↵1To whom correspondence may be addressed. Email: losapiog{at}stanford.edu or christian.schoeb{at}usys.ethz.ch.
Author contributions: G.L., C.S., P.P.A.S., and J.B. designed research; G.L. performed research; C.S., P.P.A.S., F.C., G.M.P., C.M.D.M., M.C.M., R.W.B., B.J.B., R.M.C., L.A.C., Z.K., C.J.L., R.M., F.I.P., and J.B. contributed new reagents/analytic tools; G.L. analyzed data; and G.L. wrote the paper with input from all authors.
The authors declare no competing interest.
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This article is a PNAS Direct Submission.
This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2005759118/-/DCSupplemental.
Data Availability.
All study data are included in the article and/or supporting information.
Published under the PNAS license.
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Network motifs involving both competition and facilitation predict biodiversity in alpine plant communities
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- Ecology
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