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

Aug 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: New VertLife project will sprout a forest of family trees

Provided by Wageninen University

4.8 /5 (4 votes)

Related Stories

Scientists find universal rules for food-web stability

Aug 06, 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 s ...

Physics rules network dynamics

Dec 11, 2009

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

Recommended for you

Tropical fish a threat to Mediterranean Sea ecosystems

16 hours ago

The tropical rabbitfish which have devastated algal forests in the eastern Mediterranean Sea pose a major threat to the entire Mediterranean basin if their distribution continues to expand as the climate ...

Moroccan city outlaws olive trees

17 hours ago

A Moroccan city has banned olive trees because of pollen-linked allergies and set an end-of-the-year deadline for residents to remove them, media reports said Thursday.

User comments : 0