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Including community composition in biodiversity–productivity models

Sandau, Nadine ; Rohr, Rudolf P. ; Naisbit, Russell E. ; Fabian, Yvonne ; Bruggisser, Odile T. ; Kehrli, Patrik ; Aebi, Alexandre ; Bersier, Louis-Félix

In: Methods in Ecology and Evolution, 2014, vol. 5, no. 8, p. 815–823

Studies on biodiversity and ecosystem functioning (BEF) have elicited debate over the interpretation of the positive relationship between species richness and plant productivity. Manipulating richness cannot be achieved without affecting composition; it is thus essential to consider the latter in statistical models.We firstly review existing approaches that use species richness as an explanatory...

Structure comparison of binary and weighted niche-overlap graphs

Sokhn, Nayla ; Baltensperger, Richard ; Bersier, Louis-Félix ; Ultes-Nitsche, Ulrich ; Hennebert, Jean

In: Complex Networks, 2014, vol. 5, p. 119–127

In ecological networks, niche-overlap graphs are considered as complex systems. They represent the competition between two predators that share common resources. The purpose of this paper is to investigate the structural properties of these graphs considered as weighted networks and compare their measures with the ones calculated for the binary networks. To conduct this study, we select four...

Plant diversity in a nutshell: testing for small-scale effects on trap nesting wild bees and wasps

Fabian, Yvonne ; Sandau, Nadine ; Bruggisser, Odile T. ; Aebi, Alexandre ; Kehrli, Patrik ; Rohr, Rudolf P. ; Naisbit, Russell E. ; Bersier, Louis-Félix

In: Ecosphere, 2014, vol. 5, no. 2, p. art18

Declining plant species richness in agro-ecosystems and thus reduced habitat quality can have cascading effects on ecosystem functioning, leading to reduced pollination and biological control. Here we test if plant diversity can affect arthropod diversity and abundance on a very small scale, manipulating plant species richness (2, 6, 12 and 20 sown species) in small adjacent subplots (6 × 9 m)...

Structural network properties of niche-overlap graphs

Sokhn, Nayla ; Baltensperger, Richard ; Bersier, Louis-Félix ; Nitsche, Ulrich-Ultes ; Hennebert, Jean

In: 2013 International Conference on Signal-Image Technology Internet-Based Systems (SITIS), 2013, p. 478–482

The structure of networks has always been interesting for researchers. Investigating their unique architecture allows to capture insights and to understand the function and evolution of these complex systems. Ecological networks such as food-webs and niche-overlap graphs are considered as complex systems. The main purpose of this work is to compare the topology of 15 real niche-overlap graphs...

Confédéré : journal d'information du Valais romand

Martigny : Confédéré, 1861

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Phylogenetic signal in predator–prey body-size relationships

Naisbit, Russell E. ; Kehrli, Patrik ; Rohr, Rudolf Philippe ; Bersier, Louis-Félix

In: Ecology, 2011, vol. 92, no. 12, p. 2183–2189

Body mass is a fundamental characteristic that affects metabolism, life history, and population abundance and frequently sets bounds on who eats whom in food webs. Based on a collection of topological food webs, Ulrich Brose and colleagues presented a general relationship between the body mass of predators and their prey and analyzed how mean predator–prey body-mass ratios differed among...

Body sizes of consumers and their resources

Brose, Ulrich ; Cushing, Lara ; Berlow, Eric L. ; Jonsson, Tomas ; Banasek-Richter, Carolin ; Bersier, Louis-Félix ; Blanchard, Julia L. ; Brey, Thomas ; Carpenter, Stephen R. ; Cattin Blandenier, Marie-France ; Cohen, Joel E. ; Dawah, Hassan Ali ; Dell, Tony ; Edwards, Francois ; Harper-Smith, Sarah ; Jacob, Ute ; Knapp, Roland A. ; Ledger, Mark E. ; Memmott, Jane ; Mintenbeck, Katja ; Pinnegar, John K. ; Rall, Björn C. ; Rayner, Thomas ; Ruess, Liliane ; Ulrich, Werner ; Warren, Philip ; Williams, Richard J. ; Woodward, Guy ; Yodzis, Peter ; Martinez, Neo D.

In: Ecology, 2005, vol. 86, p. 2545

Trophic information—who eats whom—and species' body sizes are two of the most basic descriptions necessary to understand community structure as well as ecological and evolutionary dynamics. Consumer–resource body size ratios between predators and their prey, and parasitoids and their hosts, have recently gained increasing attention due to their important implications for species'...

The signature of phylogenetic constraints on food-web structure

Bersier, Louis-Félix ; Kehrli, Patrik

In: Ecological Complexity, 2008/5//http://dx.doi.org/10.1016/j.ecocom.2007.06.013

Understanding the processes underlying food-web structure and organization remains one of the major tasks of ecology. While first attempts were mostly based on niche theory, with body size of species imposing a hierarchical structure for consumer species, it has been recently suggested that phylogenetic constraints may be more fundamental to understand who eats whom in natural communities. Models...

Functional responses: a question of alternative prey and predator density

Tschanz, Britta ; Bersier, Louis-Félix ; Bacher, Sven

In: Ecology, 2007, vol. 88, no. 5, p. 1300–1308

Throughout the study of ecology, there has been a growing realization that indirect effects among species cause complexity in food webs. Understanding and predicting the behavior of ecosystems consequently depends on our ability to identify indirect effects and their mechanisms. The present study experimentally investigates indirect interactions arising between two prey species that share a...

Paradoxes in the logistic equation?

Gabriel, Jean-Pierre ; Saucy, Francis ; Bersier, Louis-Félix

In: Ecological Modelling

Levins and Ginzburg raised two paradoxes concerning the logistic equation of population growth. None of them received a satisfactory answer within the frame of the original equation. Here, we propose solutions to both paradoxes.