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Accueil du site > Scientific Departments > Community diversity and ecosystem functioning > Teams > Ecology and evolution of interaction webs (EERI)

Ecology and evolution of interaction webs (EERI)

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Research themes

In the context of current large pressures exerted by human populations on natural communities, ecological sciences often cannot provide adequate predictions or management decisions. One reason is the intrinsic complexity of ecosystems.
The EERI team tries to handle a part of this complexity by focusing on the structure, functioning and evolution of ecological networks. Such network aspects are often restricted to trophic interactions (ie, food webs), with decades of research on food webs providing important insights regarding community ecology.

The EERI team participates to this global effort to understand food webs, but also tries to go beyond traditional food web approaches. First by favoring research questions that are at the interface of different sub-disciplines of ecology (community ecology, functional ecology, evolutionary ecology).
Also, most of the research topics involve simultaneously theoretical and experimental developments.

The works of the team are organized along four main axes :

► Accounting for the diversity of interaction types within ecological communities

Recently, several synthesis have underlined our need to account for several interaction types (eg, trophic and mutualistic) simultaneously, and particularly to account for non-trophic interactions in food webs. Such a diversity of interactions likely affects the structure, stability and functioning of natural communities and their ability to provide key ecosystem services.
The EERI team is particularly well suited to handle this type of questions, as researchers handle different interaction types in their works (food webs, herbivory, plant-mycorrhizae, parasitism, pollination, ecosystem engineering).

While continuing their work on these different interactions, current works of the team also try to handle two important questions :

1) What are the direct and indirect effects of a given type of interaction on an interaction of another type ?
2) What are the consequences of disturbances on complex systems that consist of several interaction types ?

► Studying the relationship between network structure and ecosystem functioning

In general, the projects of the team on this topic are also linked to the previous axis (mixing different interaction types). We are particularly interested in how the structure of ecological networks affects

1) the transfer of matter or energy fluxes or nutrient cycles in the ecosystem ;
2) the stability of ecological communities and ecosystems.

Initially, such debates at the interface of community and functional ecology have focused on the relationship between diversity within a guild and functional processes at ecosystem scale. Since, our research has extended to account for various interaction types, at larger scales (eg, structure of trophic networks, or mutualistic interaction webs).

Works on this topic within the team include various guilds and trophic groups within ecosystems and rely on experimental and theoretical approaches.

► Eco-evolutionary dynamics within interaction networks

The dynamics of interaction networks are most often restricted to variations in ecological emergent properties (eg, variations in the abundances of species), leaving out the evolutionary dynamics (eg, variations in the phenotypes within the network).
Such approaches therefore ignore or simplify the variability that exists among individuals of a given species, though such intraspecific variabilities may have large consequences for the dynamics and functioning of ecosystems.
The team tries to handle this variability for various sets of phenotypic traits, including variations in life-history traits, body sizes, predation behaviors and defense strategies.

The team also tries to disentangle how variations in phenotypes can be explained or linked to phenotypic plasticity, evolution under a certain disturbance regime, or due to the coevolution among species of the network.

To achieve this goal, the team develops theoretical models (based on adaptive dynamics or quantitative genetics), empirical analysis of trait variations in ecological datasets and phylogenetic signals in ecological communities.
Selection experiments are also undertaken.

► Effect of spatial or organisational scales

Because works of the team aim at understanding the structure of networks, we have to account for how such structures depend on the scales.
This theme is actually making a link between the three previous ones. It consists in starting with mechanisms happening at small scales (or, among individuals, within a locality) to let emerge dynamics at larger scales (eg, within metacommunities).
It also explicitly considers spatial components of ecological dynamics that have profound implications for both ecological and evolutionary dynamics.
While community dynamics remain the focus of our research, our understanding often relies on interactions happening at smaller scales and how such interactions constrain emergent properties in a bottom-up fashion.
To give two instances, we work on how interactions among individuals may help to understand variations in functional responses used to model trophic networks.
We also work on the links that exist between the amount of dispersal existing within a metacommunity and the structures of local networks observed in the various locations that make such metacommunities

Nicolas LOEUILLE, PU UPMC, EERI team leader



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