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Uncovering the role of the diversity of interaction types in nature

In ecological communities, interactions between species form complex networks that mediate their response to perturbations. So far, ecological network studies have typically focused on one (or a few) interaction types at a time, but data and models of webs including different interaction types simultaneously have recently become available. How and when does the diversity of interactions matter for the dynamics and resilience of ecological systems? My recent research aims at analyzing ecological networks including different types of interactions. Moving beyond unidimensional analyses of ecological networks may contribute to improving our understanding and predictive capacity of the way ecological systems respond to disturbances.

 

Visualize the Chilean web (by E. Berlow)

Play with the Chilean web multiplex clusters (by V. Miele)

 
Some publications:
Pilosof, S. et al. 2017. Nature in Ecology and Evolution.
Kéfi, S., V. Miele et al. 2016. PLOS Biology.
Kéfi, S. et al. 2015. Ecology.
Kéfi, S. et al. 2012. Ecology Letters.

Identifying early warning signals of catastrophic shifts in ecosystems

With the current global change, it is becoming increasingly important for us to be able to anticipate shifts in ecological communities. Shifts are often responsible for large, long-lasting changes and can result in dramatic ecological and economic consequences. Are there early warning signs that an ecosystem is loosing resilience?

Generic indicators, that can be quantified on the temporal and spatial dynamics of ecosystems, have been identified in the literature. In addition, for terrestrial ecosystems, it has been hypothesized that vegetation patchiness could be used as a signature of imminent transitions in ecosystems. Using both field data and modelling approaches, I investigate when and where these indicators can be quantified and when their predictions in terms of ecosystem degradation are reliable, with a current focus on arid ecosystems.

Arid and semi-arid ecosystems, which cover about 40% of the Earth's terrestrial surface, are expected to be among the ecosystems most sensitive to environmental changes. There are growing concerns that climatic changes may lead to increased desertification, impacting approximately 25% of the world's population. I am developing models of the vegetation dynamics in arid ecosystems aiming at better understanding the functioning of arid ecosystems and their response to changes in external conditions, such as grazing pressure or climate change. 

Learn more about the European project CASCADE

R-package on spatial early warning signals (by A. Génin)

See here for general information about early warning signals (with V. Dakos)

 

Some publications:
Génin, A. et al. 2018. Methods in Ecology and Evolution. 9(10): 2067-2075.
Berdugo, M. et al. 2017. Nature in Ecology and Evolution.
Schneider, F.D. and S. Kéfi. 2016. Theoretical Ecology.
Kéfi, S. et al. 2014. PLoS ONE.
Kéfi, S. et al. 2013. Oikos.
Kéfi, S. et al. 2011. Ecology Letters.
Kéfi, S. et al. 2007. Theoretical Population Biology.
Kéfi, S. et al. 2007. Nature.

Investigating the role of facilitation for ecosystem dynamics and resilience

In harsh environments, individuals can modify their habitat and make it more hospitable for themselves and/or others by relieving the environmental stress. Although evidence on the importance of such positive interactions is accumulating in a wide range of ecosystems, they are largely ignored by current models in ecology. Including positive interactions into ecological theory may be key to understanding population and community processes in physically stressful habitats. Studies already showed that positive interactions in the form of habitat amelioration can have profound effects on the spatial distribution of organisms, on their abundance, and on ecosystem resilience. I am interested in the role of positive interactions for the functioning of ecological communities.

Furthermore, despite their potential importance for community resilience, little is known about the role of positive interactions embedded in complex networks in stabilizing or destabilizing communities. The aim of a current project is to study the functional role of positive interactions in ecological networks. How do positive interactions affect the functioning of ecological communities, as well as the response of these communities to changing external conditions ?

 

Some publications:
Danet, A. et al. 2018. Journal of vegetation science.
Zélé, F. et al. 2018. Nature communications.
Danet, A. et al. 2017. Ecology and Evolution
Kéfi, S. et al. 2016. Functional Ecology.
Kéfi, S. et al. 2007. Theoretical Population Biology.
 
UA-11938565-1