The role of asymmetric interactions on the effect of habitat destruction in mutualistic networks

TL;DR

This paper presents a theoretical model demonstrating that asymmetric, disassortative mutualistic networks help specialist plants withstand habitat destruction by maintaining more connections through generalist pollinators, aligning with natural observations.

Contribution

The study introduces a dynamical model analyzing how asymmetric interactions influence species resilience in habitat destruction, highlighting the stabilizing role of disassortative network structures.

Findings

Disassortative networks tend to increase asymmetry after extinctions.

Specialist plants in disassortative networks retain more links during habitat loss.

Natural mutualistic networks exhibit features predicted by the model.

Abstract

Plant-pollinator mutualistic networks are asymmetric in their interactions: specialist plants are pollinated by generalist animals, while generalist plants are pollinated by a broad involving specialists and generalists. It has been suggested that this asymmetric ---or disassortative--- assemblage could play an important role in determining the equal susceptibility of specialist and generalist plants under habitat destruction. At the core of the argument lies the observation that specialist plants, otherwise candidates to extinction, could cope with the disruption thanks to their interaction with generalist pollinators. We present a theoretical framework that supports this thesis. We analyze a dynamical model of a system of mutualistic plants and pollinators, subject to the destruction of their habitat. We analyze and compare two families of interaction topologies, ranging from highly assortative to highly disassortative ones, as well as real pollination networks. We found that several features observed in natural systems are predicted by the mathematical model. First, there is a tendency to increase the asymmetry of the network as a result of the extinctions. Second, an entropy measure of the differential susceptibility to extinction of specialist and generalist species show that they tend to balance when the network is disassortative. Finally, the disappearance of links in the network, as a result of extinctions, shows that specialist plants preserve more connections than the corresponding plants in an assortative system, enabling them to resist the disruption.