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Université de Neuchâtel

Additive effects of ectoparasites over reproductive attempts in the long-lived alpine swift

Bize, Pierre ; Roulin, Alexandre ; Tella, José L. ; Bersier, Louis-Félix ; Richner, Heinz

In: Journal of animal ecology, 2004, vol. 73, no. 6, p. 1080-1088

1. Parasitism is a non-negligible cost of reproduction in wild organisms, and hosts are selected to partition resources optimally between current and future reproduction. While parents can compensate for the cost of parasitism by increasing their current reproductive investment, such change in resource allocation is expected to carry-over costs on future reproduction. 2. Life...

Université de Fribourg

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'...

Université de Neuchâtel

Complexity in quantitative food webs

Banašek-Richter, Carolin ; Bersier, Louis-Félix ; Cattin, Marie-France ; Baltensperger, Richard ; Gabriel, Jean-Pierre ; Merz, Yves ; Ulanowicz, Robert E. ; Tavares, Annette F. ; Williams, D. Dudley ; de Ruiter, Peter C. ; Winemiller, Kirk O. ; Naisbit, Russell. E.

In: Ecology, 2009, vol. 90, no. 6, p. 1470-1477

Food webs depict who eats whom in communities. Ecologists have examined statistical metrics and other properties of food webs, but mainly due to the uneven quality of the data, the results have proved controversial. The qualitative data on which those efforts rested treat trophic interactions as present or absent and disregard potentially huge variation in their magnitude, an approach similar to...

Université de Fribourg

Consumer-resource body-size relationships in natural food webs

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

In: Ecology, 2006, vol. 87, no. 10, p. 2411-2417

It has been suggested that differences in body size between consumer and resource species may have important implications for interaction strengths, population dynamics, and eventually food web structure, function, and evolution. Still, the general distribution of consumer–resource body-size ratios in real ecosystems, and whether they vary systematically among habitats or broad taxonomic...

Université de Neuchâtel

Difference in the homocysteine-lowering effect of folic acid in haemodialysis patients with and without occlusive vascular disease

Descombes, Eric ; Boulat, Olivier ; Bersier, Louis-Félix ; Fellay, Gilbert

In: Nephrology Dialysis Transplantation, 2001, vol. 16, no. 3, p. 585-589

Background. Hyperhomocysteinaemia has been identified as an independent cardiovascular risk factor and is found in more than 85% of patients on maintenance haemodialysis. Previous studies have shown that folic acid can lower circulating homocysteine in dialysis patients. We evaluated prospectively the effect of increasing the folic acid dosage from 1 to 6 mg per dialysis on plasma total...

Université de Neuchâtel

Direct and indirect bottom-up and top-down forces shape the abundance of the orb-web spider Argiope bruennichi

Bruggisser, Odile T ; Sandau, Nadine ; Blandenier, Gilles ; Fabian, Yvonne ; Kehrli, Patrik ; Aebi, Alex ; Naisbit, Russell E ; Bersier, Louis-Félix

In: Basic and Applied Ecology, 2012, vol. 13, no. 8, p. 706-714

Species abundance in local communities is determined by bottom-up and top-down processes, which can act directly and indirectly on the focal species. Studies examining these effects simultaneously are rare. Here we explore the direct top-down and direct and indirect bottom-up forces regulating the abundance and predation success of an intermediate predator, the web-building spider Argiope...

Université de Fribourg

Do spiders respond to global change? A study on the phenology of ballooning spiders in Switzerland

Blandenier, Gilles ; Bruggisser, Odile T. ; Bersier, Louis-Félix

In: Écoscience, 2014, vol. 21, no. 1, p. 79–95

We studied ballooning spiders captured weekly over an 11-y period using a 12.2-m- high suction trap in an agricultural landscape of western Switzerland. We analyzed population trends, changes in phenology, and species composition. Yearly trends in population size of the most abundant species were studied with nonparametric correlations. We found that these trends were markedly different for...

Université de Neuchâtel

Ecotones and gradient as determinants of herpetofaunal community structure in the primary forest of Mount Kupe, Cameroon

Hofer, Ulrich ; Bersier, Louis-Félix ; Borcard, Daniel

In: Journal of Tropical Ecology, 2000, vol. 16, no. 4, p. 517-533

The relative effects of the elevational gradient and of environmental discontinuities (ecotones) on the structure of a herpetofaunal assemblage in a tropical upland forest were contrasted by means of canonical correspondence analysis. Qualitative descriptors were used to define the elevational positions of the ecotones of interest, namely transitions in forest type and presence/absence of water...

Université de Neuchâtel

Effects of taxonomic and trophic aggregation on food web properties

Sugihara, George ; Bersier, Louis-Félix ; Schoenly, Kenneth

In: Oecologia, 1997, vol. 112, no. 2, p. 272-284

Historically, ecologists have been more interested in organisms feeding at the tops of food chains than in organisms feeding at or near the bottom. The problem of taxonomic and trophic inconsistency within and among described food webs is central to criticisms of contemporary food web research. To study the effects of taxonomic and trophic aggregation on food web properties, 38 published food...