title: Nested species interactions promote feasibility over stability during the assembly of a pollinator community.
abstract: The foundational concepts behind the persistence of ecological communities have been based on two ecological properties: dynamical stability and feasibility. The former is typically regarded as the capacity of a community to return to an original equilibrium state after a perturbation in species abundances and is usually linked to the strength of interspecific interactions. The latter is the capacity to sustain positive abundances on all its constituent species and is linked to both interspecific interactions and species demographic characteristics. Over the last 40 years, theoretical research in ecology has emphasized the search for conditions leading to the dynamical stability of ecological communities, while the conditions leading to feasibility have been overlooked. However, thus far, we have no evidence of whether species interactions are more conditioned by the community's need to be stable or feasible. Here, we introduce novel quantitative methods and use empirical data to investigate the consequences of species interactions on the dynamical stability and feasibility of mutualistic communities. First, we demonstrate that the more nested the species interactions in a community are, the lower the mutualistic strength that the community can tolerate without losing dynamical stability. Second, we show that high feasibility in a community can be reached either with high mutualistic strength or with highly nested species interactions. Third, we find that during the assembly process of a seasonal pollinator community located at The Zackenberg Research Station (northeastern Greenland), a high feasibility is reached through the nested species interactions established between newcomer and resident species. Our findings imply that nested mutualistic communities promote feasibility over stability, which may suggest that the former can be key for community persistence.
authors.affiliation: Department of Evolutionary Biology and Environmental Studies University of Zurich Winterthurerstrasse 190CH-8057 Zurich Switzerland; Department of Environmental Systems Science ETH Zurich Universitätstrasse 16CH-8092 Zurich Switzerland.
authors.forename: Serguei
authors.initials: S
authors.lastname: Saavedra
authors.affiliation: Department of Biology - Ecology and Evolution University of Fribourg Chemin du Musée 10 CH-1700 Fribourg Switzerland.
authors.forename: Rudolf P
authors.initials: RP
authors.lastname: Rohr
authors.affiliation: Department of Bioscience Aarhus University Ny Munkegade 166 DK-8000 Aarhus C Denmark.
authors.forename: Jens M
authors.initials: JM
authors.lastname: Olesen
authors.affiliation: Department of Evolutionary Biology and Environmental Studies University of Zurich Winterthurerstrasse 190 CH-8057 Zurich Switzerland.
authors.forename: Jordi
authors.initials: J
authors.lastname: Bascompte
keywords: Coexistence; feasibility; global stability; mutualistic networks; mutualistic strength; nestedness