title: A global analysis of bidirectional interactions in alpine plant communities shows facilitators experiencing strong reciprocal fitness costs.
abstract: Facilitative interactions are defined as positive effects of one species on another, but bidirectional feedbacks may be positive, neutral, or negative. Understanding the bidirectional nature of these interactions is a fundamental prerequisite for the assessment of the potential evolutionary consequences of facilitation. In a global study combining observational and experimental approaches, we quantified the impact of the cover and richness of species associated with alpine cushion plants on reproductive traits of the benefactor cushions. We found a decline in cushion seed production with increasing cover of cushion-associated species, indicating that being a benefactor came at an overall cost. The effect of cushion-associated species was negative for flower density and seed set of cushions, but not for fruit set and seed quality. Richness of cushion-associated species had positive effects on seed density and modulated the effects of their abundance on flower density and fruit set, indicating that the costs and benefits of harboring associated species depend on the composition of the plant assemblage. Our study demonstrates 'parasitic' interactions among plants over a wide range of species and environments in alpine systems, and we consider their implications for the possible selective effects of interactions between benefactor and beneficiary species.
authors: Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, EEZA-CSIC, Carretera de Sacramento s/n, La Cañada de San Urbano, 04120, Almería, Spain.
authors: Christian
authors: C
authors: Schöb
authors: University of Bordeaux, UMR CNRS 5805 EPOC, 33405, Talence, France.
authors: Richard
authors: R
authors: Michalet
authors: Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.|Instituto de Ecología y Biodiversidad, Casilla 653, Santiago, Chile.
authors: Lohengrin A
authors: LA
authors: Cavieres
authors: Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, EEZA-CSIC, Carretera de Sacramento s/n, La Cañada de San Urbano, 04120, Almería, Spain.
authors: Francisco I
authors: FI
authors: Pugnaire
authors: The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, UK.
authors: Rob W
authors: RW
authors: Brooker
authors: Merriam-Powell Center for Environmental Research, Northern Arizona University, PO Box 6077, Flagstaff, AZ, 86011, USA.
authors: Bradley J
authors: BJ
authors: Butterfield
authors: Department of Biological Sciences, Minnesota State University, Mankato, MN, USA.
authors: Bradley J
authors: BJ
authors: Cook
authors: 4D Research Institute, Ilia State University, 3/5 Cholokashvili Av., Tbilisi, 0162, Georgia.
authors: Zaal
authors: Z
authors: Kikvidze
authors: Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
authors: Christopher J
authors: CJ
authors: Lortie
authors: MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Sa
authors: S
authors: Xiao
authors: University of Bordeaux, UMR CNRS 5805 EPOC, 33405, Talence, France.|University of Bordeaux, UMR INRA 1202 BIOGECO, 33405, Talence, France.
authors: Patrick
authors: P
authors: Al Hayek
authors: Institut de Recherche pour le Développement (IRD), UMR AMAP, Boulevard de la Lironde, TA A-51/PS2, 34398, Montpellier Cedex 5, France.
authors: Fabien
authors: F
authors: Anthelme
authors: Division of Biological Sciences and the Institute on Ecosystems, University of Montana, Missoula, MT, 59812, USA.
authors: Brittany H
authors: BH
authors: Cranston
authors: Departamento de Botánica, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.|Instituto de Ecología y Biodiversidad, Casilla 653, Santiago, Chile.
authors: Mary-Carolina
authors: MC
authors: García
authors: University of Bordeaux, UMR CNRS 5805 EPOC, 33405, Talence, France.|Department of Botany, Faculty of Science, University of South Bohemia, Branisovska 31, CZ-370 05, Ceske Budejovice, Czech Republic.
authors: Yoann
authors: Y
authors: Le Bagousse-Pinguet
authors: Department of Forest and Conservation Sciences, University of British Columbia, 2621-2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
authors: Anya M
authors: AM
authors: Reid
authors: Department of Geosciences and Geography, University of Helsinki, PO Box 64, 00014, Helsinki, Finland.
authors: Peter C
authors: PC
authors: le Roux
authors: Department TeSAF, University of Padova, Viale dell'Universitá 16, 35020, Legnaro, Italy.
authors: Emanuele
authors: E
authors: Lingua
authors: Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
authors: Mawethu J
authors: MJ
authors: Nyakatya
authors: University of Bordeaux, UMR INRA 1202 BIOGECO, 33405, Talence, France.
authors: Blaise
authors: B
authors: Touzard
authors: Key Laboratory of Ecohydrology of Inland River Basin, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou, 730000, China.
authors: Liang
authors: L
authors: Zhao
authors: Division of Biological Sciences and the Institute on Ecosystems, University of Montana, Missoula, MT, 59812, USA.
authors: Ragan M
authors: RM
authors: Callaway
mesh_terms: D044822:Biodiversity; D017753:Ecosystem; D035264:Flowers / Q000502:physiology; D005638:Fruit / Q000502:physiology; D056084:Genetic Fitness; D016014:Linear Models; D018521:Plant Physiological Phenomena; D012639:Seeds / Q000502:physiology; D013045:Species Specificity
keywords: community feedbacks; competition; cost and benefit of facilitation; nurse plant system; parasitism; plant-plant interactions; reciprocal interactions; reproductive success