Université de Fribourg

Understanding negative biodiversity–ecosystem functioning relationship in semi-natural wildflower strips

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

In: Oecologia, 2019, vol. 189, no. 1, p. 185–197

Studies on biodiversity–ecosystem functioning (BEF) in highly controlled experiments often yield results incompatible with observations from natural systems: experimental results often reveal positive relationships between diversity and productivity, while for natural systems, zero or even negative relationships have been reported. The discrepancy may arise due to a limited or closed local...

Université de Fribourg

The relative contributions of species richness and species composition to ecosystem functioning

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

In: Oikos, 2017, vol. 126, no. 6, p. 782–791

How species diversity influences ecosystem functioning has been the subject of many experiments and remains a key question for ecology and conservation biology. However, the fact that diversity cannot be manipulated without affecting species composition makes this quest methodologically challenging. Here, we evaluate the relative importance of diversity and of composition on biomass...

Université de Fribourg

The importance of landscape and spatial structure for hymenopteran-based food webs in an agro-ecosystem

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

In: Journal of Animal Ecology, 2013, vol. 82, no. 6, p. 1203–1214

Understanding the environmental factors that structure biodiversity and food webs among communities is central to assess and mitigate the impact of landscape changes. Wildflower strips are ecological compensation areas established in farmland to increase pollination services and biological control of crop pests and to conserve insect diversity. They are arranged in networks in order to favour...

Université de Fribourg

Ecological and genetic factors influencing the transition between host-use strategies in sympatric Heliconius butterflies

Merrill, R. M. ; Naisbit, Russell E. ; Mallet, J. ; Jiggins, Chris D.

In: Journal of Evolutionary Biology, 2013, vol. 26, no. 9, p. 1959–1967

Shifts in host-plant use by phytophagous insects have played a central role in their diversification. Evolving host-use strategies will reflect a trade-off between selection pressures. The ecological niche of herbivorous insects is partitioned along several dimensions, and if populations remain in contact, recombination will break down associations between relevant loci. As such, genetic...

Université de Fribourg

Diversity protects plant communities against generalist molluscan herbivores

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

In: Ecology and Evolution, 2012, vol. 2, no. 10, p. 2460-2473

Wildflower strips are used to increase natural enemies of crop pests and to conserve insect diversity on farmland. Mollusks, especially slugs, can affect the vegetation development in these strips considerably. Although recent theoretical work suggests that more diverse plant communities will exhibit greater resistance against herbivore pressure, empirical studies are scarce. We conducted a...

Université de Fribourg

Phylogeny versus body size as determinants of food web structure

Naisbit, Russell E. ; Rohr, Rudolf P. ; Rossberg, Axel G. ; Kehrli, Patrik ; Bersier, Louis-Félix

In: Proceedings of the Royal Society B: Biological Sciences, 2012, p. -

Food webs are the complex networks of trophic interactions that stoke the metabolic fires of life. To understand what structures these interactions in natural communities, ecologists have developed simple models to capture their main architectural features. However, apparently realistic food webs can be generated by models invoking either predator–prey body-size hierarchies or evolutionary...

Université de Fribourg

Climate oscillations and species interactions: large-scale congruence but regional differences in the phylogeographic structures of an alpine plant and its monophagous insect

Borer, Matthias ; Arrigo, Nils ; Buerki, Sven ; Naisbit, Russell E. ; Alvarez, Nadir

In: Journal of Biogeography, 2012, p. -

Aim To predict the fate of alpine interactions involving specialized species, using a monophagous beetle and its host plant as a case study.Location The Alps.Methods We investigated genetic structuring of the herbivorous beetle Oreina gloriosa and its specific host-plant Peucedanum ostruthium. We used genome fingerprinting (in the insect and the plant) and sequence data (in the insect)...

Université de Fribourg

Do induced responses mediate the ecological interactions between the specialist herbivores and phytopathogens of an alpine plant?

Röder, Gregory ; Rahier, Martine ; Naisbit, Russell E.

In: PLoS ONE, 2011, vol. 6, no. 5, p. e19571

Plants are not passive victims of the myriad attackers that rely on them for nutrition. They have a suite of physical and chemical defences, and are even able to take advantage of the enemies of their enemies. These strategies are often only deployed upon attack, so may lead to indirect interactions between herbivores and phytopathogens. In this study we test for induced responses in wild...

Université de Fribourg

The phylogeography of an alpine leaf beetle: Divergence within Oreina elongata spans several ice ages

Borer, Matthias ; Alvarez, Nadir ; Buerki, Sven ; Margraf, Nicolas ; Rahier, Martine ; Naisbit, Russell E.

In: Molecular Phylogenetics and Evolution, 2010, vol. 57, no. 2, p. 703-709

The genetic landscape of the European flora and fauna was shaped by the ebb and flow of populations with the shifting ice during Quaternary climate cycles. While this has been well demonstrated for lowland species, less is known about high altitude taxa. Here we analyze the phylogeography of the leaf beetle Oreina elongata from 20 populations across the Alps and Apennines. Three mitochondrial and...