Interspecific competition underlying mutualistic networks

TL;DR

This paper models the evolution of mutualistic networks, revealing how asymmetry and competition influence their topology, leading to specific degree distributions observed in real-world pollination networks.

Contribution

It introduces a model linking network topology to partner selection asymmetry and competition, explaining observed degree distributions in mutualistic networks.

Findings

Mutualistic network topology depends on partner selection asymmetry.

Competition among species influences degree distribution shapes.

Real-world networks show stretched-exponential degree distributions.

Abstract

The architecture of bipartite networks linking two classes of constituents is affected by the interactions within each class. For the bipartite networks representing the mutualistic relationship between pollinating animals and plants, it has been known that their degree distributions are broad but often deviate from power-law form, more significantly for plants than animals. Here we consider a model for the evolution of the mutualistic networks and find that their topology is strongly dependent on the asymmetry and non-linearity of the preferential selection of mutualistic partners. Real-world mutualistic networks analyzed in the framework of the model show that a new animal species determines its partners not only by their attractiveness but also as a result of the competition with pre-existing animals, which leads to the stretched-exponential degree distributions of plant species.