The type of interaction between species might play a fundamental part in the stability of ecological communities

August 13, 2010

Elisa Thébault and Colin Fontaine, with a research carried out at Imperial College London, Wageninen University and the Museum National d’Histoire Naturelle, have shown that the network architectures which favor the stability of ecological communities differ between trophic webs (“who eats who”) and mutualistic webs (“who pollinates who”).

Their theoretical results reveal that, in order to be stable, mutualistic interaction webs should present a nested architecture whereas trophic webs should adopt a compartmented architecture. This difference in architecture can be found in a large number of empirical pollination (mutualist) and herbivory (trophic) webs. This work is a major breakthrough for a better understanding of the functioning and stability of communities. These results are published in the Science issue of 13 august 2010.

Networks of ecological interactions describe the relations between within a community: for example “who eats who” for a trophic web1 or “who pollinates who” for a plant-pollinator mutualistic web2. The architecture of these networks describes the way the interactions are distributed among species; an architecture is compartmented when a network is built of different groups of species which interact more within groups than between groups (figure 1), while a nested architecture corresponds to a network that is organized around a unique group of generalist species interacting between themselves and with more specialist species (figure 2). As for the stability of a community (i.e. all the species of the network), it characterizes the ability of the community to resist to perturbations.

To date research on the relations between the architecture of ecological networks and the stability of communities had focused on one type of interaction at a time (mainly trophic interactions), making difficult the comparison between different types of networks.

In this study, the authors have realized a comparison between trophic and mutualistic networks and have investigated if the type of interaction (mutualistic or trophic) affects the relation between network architecture and community stability. They compared the results of a theoretical approach (dynamical model) with the architecture of a large dataset of published empirical networks describing 34 pollination networks (mutualist) and 23 herbivory networks (trophic).

Results show that the network architectures which favor the stability of ecological communities differ between trophic and mutualistic networks. Indeed a highly connected and nested architecture, i.e. with many generalist species interacting both between themselves and with specialist species, stabilize mutualistic networks; whereas a weakly connected and highly compartmented architecture, i.e. with few generalist species and species that interact within delimited groups, stabilize trophic networks.

This research brings important perspectives for a better understanding of the functioning of ecosystems and their response to environmental disturbances:

  • How to define relevant and functional indicators of ecosystem stability with the architecture of interaction networks?

  • How networks of different interaction types with different architectures can be combined together to form the large that link all the species in an ecosystem? And how does it interact with ecosystem functioning and stability?

Explore further: Which came first, the moth or the cactus?

Related Stories

Scientists find universal rules for food-web stability

August 6, 2009

The findings, published in this week's issue of Science, conclude that food-web stability is enhanced when many diverse predator-prey links connect high and intermediate trophic levels. The computations also reveal that small ...

Physics rules network dynamics

December 11, 2009

( -- When it comes to the workings of the Web, the brain, or a social network, physics finds universal truths.

Recommended for you

Panda habitat shrinking, becoming more fragmented

September 25, 2017

A study by Chinese and U.S. scientists finds that while populations of the iconic giant panda have increased recently, the species' habitat still covers less area and is more fragmented than when it was first listed as an ...

With extra sugar, leaves get fat too

September 25, 2017

Eat too much without exercising and you'll probably put on a few pounds. As it turns out, plant leaves do something similar. In a new study at the U.S. Department of Energy's Brookhaven National Laboratory, scientists show ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.