Competition-induced increase of species abundance in mutualistic networks

TL;DR

This study explores how exploitative competition among pollinators influences the structure and species abundance in mutualistic plant-pollinator networks, revealing that increased competition can boost plant abundance and alter network topology.

Contribution

It introduces a model analyzing the effects of exploitative competition on network structure and species abundance, highlighting the emergence of super-hub pollinators and increased plant abundance.

Findings

Pollinator competition leads to the emergence of super-hub pollinators.

Plant species abundance increases with stronger exploitative competition.

Network structure adapts to optimize mutualistic benefits and reduce competition costs.

Abstract

Nutrients from a flowering plant are shared by its pollinators, giving rise to competition in the latter. Such exploitative competition of pollinators can limit their abundance and affect the global organization of the mutualistic partnership in the plant-pollinator mutualistic community. Here we investigate the effects of the exploitative competition between pollinators on the structure and the species abundance of the mutualistic networks which evolve by changing mutualistic partnership towards higher abundance of species. Simulations show different emergent network characteristics between plants and animals; hub plants connected to many pollinators are very rare while a few super-hub pollinators appear with the exploitative competition included, in contrast to equally many hubs of both types without the exploitative competition. More interestingly, the abundance of plant species increases with increasing the exploitative competition strength. We analyze the inverse of the generalized interaction matrix in the weak-interaction limit to identify the leading structural factors relevant to the species abundance, which are shown to be instrumental in optimizing the network structure to increase the mutualistic benefit and lower the cost of exploitative competition.