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Opposing community assembly patterns for dominant and jonnondominant plant species in herbaceous ecosystems globally

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journal contribution
posted on 17.01.2022, 03:40 authored by CA Arnillas, ET Borer, EW Seabloom, J Alberti, S Baez, JD Bakker, EH Boughton, YM Buckley, MN Bugalho, I Donohue, J Dwyer, A Eskelinen, J Firn, R Gridzak, N Hagenah, Y Hautier, A Helm, A Jentsch, JMH Knops, KJ Komatsu, L Laanisto, R Laungani, R McCulley, JL Moore, John MorganJohn Morgan, PL Peri, SA Power, Jodi Price, M Sankaran, B Schamp, K Speziale, R Standish, R Virtanen, MW Cadotte
Biotic and abiotic factors interact with dominant plants—the locally most frequent or with the largest coverage—and nondominant plants differently, partially because dominant plants modify the environment where nondominant plants grow. For instance, if dominant plants compete strongly, they will deplete most resources, forcing nondominant plants into a narrower niche space. Conversely, if dominant plants are constrained by the environment, they might not exhaust available resources but instead may ameliorate environmental stressors that usually limit nondominants. Hence, the nature of interactions among nondominant species could be modified by dominant species. Furthermore, these differences could translate into a disparity in the phylogenetic relatedness among dominants compared to the relatedness among nondominants. By estimating phylogenetic dispersion in 78 grasslands across five continents, we found that dominant species were clustered (e.g., co-dominant grasses), suggesting dominant species are likely organized by environmental filtering, and that nondominant species were either randomly assembled or overdispersed. Traits showed similar trends for those sites (<50%) with sufficient trait data. Furthermore, several lineages scattered in the phylogeny had more nondominant species than expected at random, suggesting that traits common in nondominants are phylogenetically conserved and have evolved multiple times. We also explored environmental drivers of the dominant/nondominant disparity. We found different assembly patterns for dominants and nondominants, consistent with asymmetries in assembly mechanisms. Among the different postulated mechanisms, our results suggest two complementary hypotheses seldom explored: (1) Nondominant species include lineages adapted to thrive in the environment generated by dominant species. (2) Even when dominant species reduce resources to nondominant ones, dominant species could have a stronger positive effect on some nondominants by ameliorating environmental stressors affecting them, than by depleting resources and increasing the environmental stress to those nondominants. These results show that the dominant/nondominant asymmetry has ecological and evolutionary consequences fundamental to understand plant communities.

Funding

National Science Foundation, Grant/ Award Number: NSF-DEB-1042132 and NSF-DEB-1234162; Natural Sciences and Engineering Research Council of Canada, Grant/Award Number: 386151; Institute on the Environment, University of Minnesota, Grant/Award Number: DG-0001-13; Portuguese Science Foundation, Grant/ Award Number: IF/01171/2014

History

Publication Date

01/12/2021

Journal

Ecology and Evolution

Volume

11

Issue

24

Pagination

18p. (p. 17744-17761)

Publisher

Wiley

ISSN

2045-7758

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The Author reserves all moral rights over the deposited text and must be credited if any re-use occurs. Documents deposited in OPAL are the Open Access versions of outputs published elsewhere. Changes resulting from the publishing process may therefore not be reflected in this document. The final published version may be obtained via the publisher’s DOI. Please note that additional copyright and access restrictions may apply to the published version.