The interplay between mutualism, competition and dispersal promotes species coexistence in a multiple interactions type system

Abstract

The stability and maintenance of species biodiversity in the multiple interactions type systems have attracted much attention. Regardless of their nature, several forms of interactions are discovered to exhibit oscillatory behaviour. This large-amplitude oscillation also de-stabilizes populations of multiple species and raises species’ chances of extinction. A central question in ecology is how do we maintain community stability and species coexistence mechanisms in a multiple interactions type community. It is thought that the dynamics of mutualism support multi-species coexistence in a complex ecological system. Here, we extend a four-species multiple interactions type (e.g., resource-competitor-exploiter-mutualist) system by incorporating a local dispersal component. We then employ this model to assess how the combined impacts of dispersal, mutualism and competition shape species coexistence and community stability in this ecological system. Our findings show that the interplay of mutualism and competition affects the complexity of ecological dynamics in this multiple interactions type system with local dispersal. Using numerical simulation, we demonstrate how strong mutualism could stabilize the spatio-temporal dynamics. Employing bifurcation analysis, we also discover that mutualism essentially modifies this ecological community’s response to increasing competitive pressure on the resource species. These insights are evident in our findings through the emergence of intriguing dynamics where stable limit cycles alternate with unstable ones as competitive pressure varies. While alternative stable states are common in different ecological systems with mutualistic interactions, they are often stable, whereas, in our studies, we realize that there can be alternative stable or unstable states if the spatial dimension is considered through the incorporation of the diffusion component. Consequently, the long-term dynamics converge to multi-species coexistence outcomes either via a stable steady state or a limit cycle depending on species’ initial abundances. It is also observed that this complexity ceases when mutualism becomes strong enough. Additionally, the destabilization of species biodiversity phenomenon through the occurrence of limit cycles increasing in the amplitude of oscillations (with some species population densities approaching zero) is weakened in the presence of strong mutualistic strength and local dispersal. Overall, the joint effects of mutualism, competition and local dispersal result in different community compositions, and these insights may have significant consequences in conservation management and biological control strategies.