Université de Fribourg

Beware z-scores

Song, Chuliang ; Rohr, Rudolf P. ; Saavedra, Serguei

In: Journal of Animal Ecology, 2019, vol. 88, no. 5, p. 808–809

Song, Rohr, and Saavedra (2017) have proposed a methodology to compare network properties across systems with different sizes and constraints, in response to the fact that z‐scores cannot be used for such purposes. Simmons, Hoeppke, and Sutherland (2019) have shown that part of the methodology can be improved. Here, we show that all previous results hold and are strengthened by the new...

Université de Fribourg

Comparing species interaction networks along environmental gradients: Networks along environmental gradients

Pellissier, Loïc ; Albouy, Camille ; Bascompte, Jordi ; Farwig, Nina ; Graham, Catherine ; Loreau, Michel ; Maglianesi, Maria Alejandra ; Melián, Carlos J. ; Pitteloud, Camille ; Roslin, Tomas ; Rohr, Rudolf ; Saavedra, Serguei ; Thuiller, Wilfried ; Woodward, Guy ; Zimmermann, Niklaus E. ; Gravel, Dominique

In: Biological Reviews, 2018, vol. 93, no. 2, p. 785–800

Knowledge of species composition and their interactions, in the form of interaction networks, is required to understand processes shaping their distribution over time and space. As such, comparing ecological networks along environmental gradients represents a promising new research avenue to understand the organization of life. Variation in the position and intensity of links within networks...

Université de Fribourg

A guideline to study the feasibility domain of multi-trophic and changing ecological communities

Song, Chuliang ; Rohr, Rudolf P. ; Saavedra, Serguei

In: Journal of Theoretical Biology, 2018, vol. 450, p. 30–36

The feasibility domain of an ecological community can be described by the set of environmental abiotic and biotic conditions under which all co-occurring and interacting species in a given site and time can have positive abundances. Mathematically, the feasibility domain corresponds to the parameter space compatible with positive (feasible) solutions at equilibrium for all the state variables...

Université de Fribourg

Nested species interactions promote feasibility over stability during the assembly of a pollinator community

Saavedra, Serguei ; Rohr, Rudolf P. ; Olesen, Jens M. ; Bascompte, Jordi

In: Ecology and Evolution, 2016, p. -

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...

Université de Fribourg

Persist or produce: a community trade-off tuned by species evenness

Rohr, Rudolf P. ; Saavedra, Serguei ; Peralta, Guadalupe ; Frost, Carol M. ; Bersier, Louis-Félix ; Bascompte, Jordi ; Tylianakis, Jason M.

In: The American Naturalist, 2016, vol. 188, no. 4, p. 411–422

Understanding the effects of biodiversity on community persistence and productivity is key to managing both natural and production systems. Because rare species face greater danger of extinction, species evenness, a measure of how similar abundances are across species in a community, is seen as a key component of biodiversity. However, previous studies have failed to find a consistent...

Université de Fribourg

Reorganization of interaction networks modulates the persistence of species in late successional stages

Saavedra, Serguei ; Cenci, Simone ; del-Val, Ek ; Boege, Karina ; Rohr, Rudolf P.

In: Journal of Animal Ecology, 2017, vol. 86, no. 5, p. 1136–1146

Ecological interaction networks constantly reorganize as interspecific interactions change across successional stages and environmental gradients. This reorganization can also be associated with the extent to which species change their preference for types of niches available in their local sites. Despite the pervasiveness of these interaction changes, previous studies have revealed that...

Université de Fribourg

Seasonal species interactions minimize the impact of species turnover on the likelihood of community persistence

Saavedra, Serguei ; Rohr, Rudolf Philippe ; Fortuna, Miguel ; Selva, Nuria ; Bascompte, Jordi

In: Ecology, 2015, p. -

Many of the observed species interactions embedded in ecological communities are not permanent, but are characterized by temporal changes that are observed along with abiotic and biotic variations. While work has been done describing and quantifying these changes, little is known about their consequences for species coexistence. Here, we investigate the extent to which changes of species...

Université de Fribourg

A structural approach for understanding multispecies coexistence

Saavedra, Serguei ; Rohr, Rudolf P. ; Bascompte, Jordi ; Godoy, Oscar ; Kraft, Nathan J. B. ; Levine, Jonathan M.

In: Ecological Monographs, 2017, p. -

Although observations of species-rich communities have long served as a primary motivation for research on the coexistence of competitors, the majority of our empirical and theoretical understanding comes from two-species systems. How much of the coexistence observed in species rich communities results from indirect effects among competitors that only emerge in diverse systems remains poorly...

Université de Fribourg

On the structural stability of mutualistic systems

Rohr, Rudolf P. ; Saavedra, Serguei ; Bascompte, Jordi

In: Science, 2014, vol. 345, no. 6195, p. 1253497

In theoretical ecology, traditional studies based on dynamical stability and numerical simulations have not found a unified answer to the effect of network architecture on community persistence. Here, we introduce a mathematical framework based on the concept of structural stability to explain such a disparity of results. We investigated the range of conditions necessary for the stable...

Université de Fribourg

Towards the integration of niche and network theories

Godoy, Oscar ; Bartomeus, Ignasi ; Rohr, Rudolf P. ; Saavedra, Serguei

In: Trends in Ecology & Evolution, 2018, vol. 33, no. 4, p. 287–300

The quest for understanding how species interactions modulate diversity has progressed by theoretical and empirical advances following niche and network theories. Yet, niche studies have been limited to describe coexistence within tropic levels despite incorporating information about multi-trophic interactions. Network approaches could address this limitation, but they have ignored the...